Language and the aging brain: patterns of neural compensation revealed by functional brain imaging

Aging of lexical access in Chinese spoken word production: A picture-word interference study

It remains unknown how language-production processes decline with age. Using a picture-word interference task, the aim of this study was to investigate the influence of aging on lexical access and the contributions of language-specific and domain-general factors to semantic, phonological, and orthographic effects in Chinese spoken word production. After controlling for years of education, language comprehension, and domain-general cognitive abilities, we found a larger semantic interference effect for older speakers than for younger speakers, while the phonological effect and orthographic effect were comparable for the two age groups, supporting the transmission deficit hypothesis. Furthermore, discourse comprehension and general cognitive abilities were found to contribute to the phonological effect in older adults, but not in younger adults. Our findings indicate that both language-specific factors and domain-general factors contribute to the aging of spoken word production together.

Community-based interventions for mitigating cognitive-linguistic decline in older adults

Introduction

This study focuses on exploring the effectiveness of interventions in two community-based language rehabilitation care centers located in an economically underdeveloped region of northwest China.

Method

The research focuses on 35 older adults with cognitive-linguistic decline enrolled in both centers. The interventions provided to the participants include auditory training, sign language use enhancement, second language interest classes, and the promotion of elderly-mode applications on smartphones.

Results

The interventions were particularly effective in enhancing auditory processing and language comprehension skills. Additionally, the promotion of elderly-mode applications on smartphones proved to be a valuable tool in improving participants' language cognition.

Conclusion

The study underscores the importance of tailored community-based interventions in improving language skills and cognition and provides a basis for further research in this area.

Functional correlation tensors in brain white matter and the effects of normal aging

Resting state correlations between blood oxygenation level dependent (BOLD) MRI signals from voxels in white matter (WM) are demonstrably anisotropic, so that functional correlation tensors (FCT) may be used to quantify the underlying microstructure of BOLD effects in WM tracts. However, the overall spatial distribution of FCTs and their metrics in specific populations has not yet been established, and the factors that affect their precise arrangements remain unclear. Changes in WM occur with normal aging, and these may be expected to affect FCTs. We hypothesized that FCTs exhibit a characteristic spatial pattern and may show systematic changes with aging or other factors. Here we report our analyses of the FCT characteristics of fMRI images of a large cohort of 461 cognitively normal subjects (190 females, 271 males) sourced from the Open Access Series of Imaging Studies (OASIS), with age distributions of 42 y/o - 95 y/o. Group averages and statistics of FCT indices, including axial functional correlations, radial functional correlations, mean functional correlations and fractional anisotropy, were quantified in WM bundles defined by the JHU ICBM-DTI-81 WM atlas. In addition, their variations with normal aging were examined. The results revealed a dimorphic distribution of changes in FCT metrics with age, with decreases of the functional correlations in some regions and increases in others. Supplementary analysis revealed that females exhibited significant age effects on a greater number of WM areas, but the interaction between age and sex was not significant. The findings demonstrate the reproducibility of the spatial distribution of FCT metrics and reveal subtle regional changes with age.

Visual selective attention in individuals with age-related hearing loss

Evidence from epidemiological studies suggests that hearing loss is associated with an accelerated decline in cognitive function, but the underlying pathophysiological mechanism remains poorly understood. Studies using auditory tasks have suggested that degraded auditory input increases the cognitive load for auditory perceptual processing and thereby reduces the resources available for other cognitive tasks. Attention-related networks are among the systems overrecruited to support degraded auditory perception, but it is unclear how they function when no excessive recruitment of cognitive resources for auditory processing is needed. Here, we implemented an EEG study using a nonauditory visual attentional selection task in 30 individuals with age-related hearing loss (ARHLs, 60-73 years) and compared them with aged (N = 30, 60-70 years) and young (N = 35, 22-29 years) normal-hearing controls. Compared with their normal-hearing peers, ARHLs demonstrated a significant amplitude reduction for the posterior contralateral N2 component, which is a well-validated index of the allocation of selective visual attention, despite the comparable behavioral performance. Furthermore, the amplitudes were observed to correlate significantly with hearing acuities (pure tone audiometry thresholds) and higher-order hearing abilities (speech-in-noise thresholds) in aged individuals. The target-elicited alpha lateralization, another mechanism of visuospatial attention, demonstrated in control groups was not observed in ARHLs. Although behavioral performance is comparable, the significant decrease in N2pc amplitude in ARHLs provides neurophysiologic evidence that may suggest a visual attentional deficit in ARHLs even without extra-recruitment of cognitive resources by auditory processing. It supports the hypothesis that constant degraded auditory input in ARHLs has an adverse impact on the function of cognitive control systems, which is a possible mechanism mediating the relationship between hearing loss and cognitive decline.

Transcranial photobiomodulation on the left inferior frontal gyrus enhances Mandarin Chinese L1 and L2 complex sentence processing performances

This study investigated the causal enhancing effect of transcranial photobiomodulation (tPBM) over the left inferior frontal gyrus (LIFG) on syntactically complex Mandarin Chinese first language (L1) and second language (L2) sentence processing performances. Two (L1 and L2) groups of participants (thirty per group) were recruited to receive the double-blind, sham-controlled tPBM intervention via LIFG, followed by the sentence processing, the verbal working memory (WM), and the visual WM tasks. Results revealed a consistent pattern for both groups: (a) tPBM enhanced sentence processing performance but not verbal WM for linear processing of unstructured sequences and visual WM performances; (b) Participants with lower sentence processing performances under sham tPBM benefited more from active tPBM. Taken together, the current study substantiated that tPBM enhanced L1 and L2 sentence processing, and would serve as a promising and cost-effective noninvasive brain stimulation (NIBS) tool for future applications on upregulating the human language faculty.

Registered report: Age-preserved semantic memory and the CRUNCH effect manifested as differential semantic control networks: An fMRI study

Semantic memory representations are generally well maintained in aging, whereas semantic control is thought to be more affected. To explain this phenomenon, this study tested the predictions of the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH), focusing on task demands in aging as a possible framework. The CRUNCH effect would manifest itself in semantic tasks through a compensatory increase in neural activation in semantic control network regions but only up to a certain threshold of task demands. This study compares 39 younger (20-35 years old) with 39 older participants (60-75 years old) in a triad-based semantic judgment task performed in an fMRI scanner while manipulating task demand levels (low versus high) through semantic distance. In line with the CRUNCH predictions, differences in neurofunctional activation and behavioral performance (accuracy and response times) were expected in younger versus older participants in the low- versus high-demand conditions, which should be manifested in semantic control Regions of Interest (ROIs). Our older participants had intact behavioral performance, as proposed in the literature for semantic memory tasks (maintained accuracy and slower response times (RTs)). Age-invariant behavioral performance in the older group compared to the younger one is necessary to test the CRUNCH predictions. The older adults were also characterized by high cognitive reserve, as our neuropsychological tests showed. Our behavioral results confirmed that our task successfully manipulated task demands: error rates, RTs and perceived difficulty increased with increasing task demands in both age groups. We did not find an interaction between age group and task demand, or a statistically significant difference in activation between the low- and high-demand conditions for either RTs or accuracy. As for brain activation, we did not find the expected age group by task demand interaction, or a significant main effect of task demand. Overall, our results are compatible with some neural activation in the semantic network and the semantic control network, largely in frontotemporoparietal regions. ROI analyses demonstrated significant effects (but no interactions) of task demand in the left and right inferior frontal gyrus, the left posterior middle temporal gyrus, the posterior inferior temporal gyrus and the prefrontal gyrus. Overall, our test did not confirm the CRUNCH predictions.

The Costs (and Benefits?) of Effortful Listening for Older Adults: Insights from Simultaneous Electrophysiology, Pupillometry, and Memory

Although the impact of acoustic challenge on speech processing and memory increases as a person ages, older adults may engage in strategies that help them compensate for these demands. In the current preregistered study, older adults (n = 48) listened to sentences-presented in quiet or in noise-that were high constraint with either expected or unexpected endings or were low constraint with unexpected endings. Pupillometry and EEG were simultaneously recorded, and subsequent sentence recognition and word recall were measured. Like young adults in prior work, we found that noise led to increases in pupil size, delayed and reduced ERP responses, and decreased recall for unexpected words. However, in contrast to prior work in young adults where a larger pupillary response predicted a recovery of the N400 at the cost of poorer memory performance in noise, older adults did not show an associated recovery of the N400 despite decreased memory performance. Instead, we found that in quiet, increases in pupil size were associated with delays in N400 onset latencies and increased recognition memory performance. In conclusion, we found that transient variation in pupil-linked arousal predicted trade-offs between real-time lexical processing and memory that emerged at lower levels of task demand in aging. Moreover, with increased acoustic challenge, older adults still exhibited costs associated with transient increases in arousal without the corresponding benefits.

Hearing loss and dementia in older adults: A narrative review

The prevalence of hearing loss is high among older adults; globally, 65% of adults over 60 years have hearing loss. Over the past decade, evidence from epidemiologic studies has linked hearing loss to nearly two times greater risk of dementia. The hypothesized mechanistic pathways through which hearing loss could contribute to increased dementia risk include the effects of hearing on greater cognitive load, changes in brain structure and function, and decreased social engagement. These mechanistic pathways may be modified by management of hearing loss using existing intervention (eg, hearing aids). Hearing treatment may be an effective intervention for slowing cognitive decline in some older adults. In this review, we update existing reviews of the current epidemiologic research on the association between hearing loss and dementia risk and discuss hypothesized mechanisms of this association. We also discuss management of hearing loss as a potential intervention for slowing cognitive decline and reducing dementia risk.

Ageing of grammatical advance planning in spoken sentence production: an eye movement study

This study used an image-description paradigm with concurrent eye movement recordings to investigate differences of grammatical advance planning between young and older speakers in spoken sentence production. Participants were asked to produce sentences with simple or complex initial phrase structures (IPS) in Experiment 1 while producing individual words in Experiment 2. Young and older speakers showed comparable speaking latencies in sentence production task, whereas older speakers showed longer latencies than young speakers in word production task. Eye movement data showed that compared with young speakers, older speakers had higher fixation percentage on object 1, lower percentage of gaze shift from object 1 to 2, and lower fixation percentage on object 2 in simple IPS sentences, while they showed similar fixation percentage on object 1, similar percentage of gaze shift from object 1 to 2, and lower fixation percentage on object 2 in complex IPS sentences, indicating a decline of grammatical encoding scope presenting on eye movement patterns. Meanwhile, speech analysis showed that older speakers presented longer utterance duration, slower speech rate, and longer and more frequently occurred pauses in articulation, indicating a decline of speech articulation in older speakers. Thus, our study suggests that older speakers experience an ageing effect in the sentences with complex initial phrases due to limited cognitive resources.

The influence of induced moods on aging of phonological encoding in spoken word production: an ERP study

This study investigated the influence of induced mood on the phonological encoding involved in Chinese spoken word production with a picture-word inference task while concurrently recorded electrophysiological signals. In the experiment, young and older participants watched videos for inducing positive, negative, or neutral mood, and then they were instructed to name target picture while ignoring phonologically related or unrelated distractor words. A phonological facilitation effect was observed in young adults but not in older adults, suggesting an age-related decline of phonological encoding. Both groups showed an inhibition effect in negative mood but not in positive mood, suggesting that speakers have different processing styles in different moods. ERP data revealed a phonological effect around the time window of 250-350 ms in both groups. Meanwhile, young adults showed a phonological effect around 350-450 ms in negative mood and positive mood which may reflect self-monitoring in speech production. We suggest that the former effect may reflect phonological encoding while the latter reflects self-monitoring of internal syllables or phonemes. Furthermore, induced moods influence the phonological effect in older and young adults differently. Behavioral and ERP results provide consistent evidence for the aging decline of phonological encoding in spoken word production.

Effects of age on the time course of syntactic priming in Chinese sentence production: an ERP study

Using a syntactic priming task, we investigated the time course of syntactic encoding in Chinese sentence production and compared encoding patterns between younger and older adults. Participants alternately read sentence descriptions and overtly described pictures, while event-related potentials (ERPs) were recorded. We manipulated the abstract prime structure (active or passive) as well as the lexical overlap of the prime and the target (verb overlap or no overlap). The syntactic choice results replicated classical abstract priming and lexical boost effects in both younger and older adults. However, when production latency was taken into account, the speed benefit from syntactic repetition differed between the two age groups. Meanwhile, preferred priming facilitated production in both age groups, whereas nonpreferred priming inhibited production in the older group. For electroencephalography, an earlier effect of syntactic repetition and a later effect of lexical overlap showed a two-stage pattern of syntactic encoding. Older adults also showed a more delayed and interactive encoding pattern than younger adults, indicating a greater reliance on lexical information. These results are illustrative of the two-stage competition and residual activation models.

Spatiotemporal dedifferentiation of the global brain signal topography along the adult lifespan

Age-related variations in many regions and/or networks of the human brain have been uncovered using resting-state functional magnetic resonance imaging. However, these findings did not account for the dynamical effect the brain's global activity (global signal [GS]) causes on local characteristics, which is measured by GS topography. To address this gap, we tested GS topography including its correlation with age using a large-scale cross-sectional adult lifespan dataset (n = 492). Both GS topography and its variation with age showed frequency-specific patterns, reflecting the spatiotemporal characteristics of the dynamic change of GS topography with age. A general trend toward dedifferentiation of GS topography with age was observed in both spatial (i.e., less differences of GS between different regions) and temporal (i.e., less differences of GS between different frequencies) dimensions. Further, methodological control analyses suggested that although most age-related dedifferentiation effects remained across different preprocessing strategies, some were triggered by neuro-vascular coupling and physiological noises. Together, these results provide the first evidence for age-related effects on global brain activity and its topographic-dynamic representation in terms of spatiotemporal dedifferentiation.

Auditory, Lexical, and Multitasking Demands Interactively Impact Listening Effort

PURPOSE

This study examined the extent to which acoustic, linguistic, and cognitive task demands interactively impact listening effort.

METHOD

Using a dual-task paradigm, on each trial, participants were instructed to perform either a single task or two tasks. In the primary word recognition task, participants repeated Northwestern University Auditory Test No. 6 words presented in speech-shaped noise at either an easier or a harder signal-to-noise ratio (SNR). The words varied in how commonly they occur in the English language (lexical frequency). In the secondary visual task, participants were instructed to press a specific key as soon as a number appeared on screen (simpler task) or one of two keys to indicate whether the visualized number was even or odd (more complex task).

RESULTS

Manipulation checks revealed that key assumptions of the dual-task design were met. A significant three-way interaction was observed, such that the expected effect of SNR on effort was only observable for words with lower lexical frequency and only when multitasking demands were relatively simpler.

CONCLUSIONS

This work reveals that variability across speech stimuli can influence the sensitivity of the dual-task paradigm for detecting changes in listening effort. In line with previous work, the results of this study also suggest that higher cognitive demands may limit the ability to detect expected effects of SNR on measures of effort. With implications for real-world listening, these findings highlight that even relatively minor changes in lexical and multitasking demands can alter the effort devoted to listening in noise.

Cochlear Implantation in the Elderly: Speech Performance, Associated Factor, Complication, and Surgical Safety

BACKGROUND AND OBJECTIVES

The guidelines for cochlear implantation (CIs) are expanding, and the number of CI procedures performed on the elderly is increasing. The purpose of this study was to analyze the results and safety of cochlear implantation in the elderly, as well as to evaluate the predictive factors on CI outcomes.

SUBJECTS AND METHODS

The study included 56 patients aged ≥40 years, who received CIs between 2009 and 2020. They were divided into two groups: 27 younger adults (40-64 years) and 29 elderly (>64 years). The study compared their pre- and postoperative speech perception and category of auditory performance (CAP) scores, surgical complications, and hospitalization periods. It also evaluated associated factors in the elderly group by examining categorical and continuous variables and postoperative CAP score.

RESULTS

There was a significant improvement in speech recognition tests (both word and sentence) and CAP scores in both groups compared to the pre-implantation scores (p<0.001). Postoperative results were slightly lower in the elderly group than in younger adults for sentence recognition and CAP scores, except for word recognition. No significant associated factors were found on postoperative CAP scores, except for etiology. Postoperative CAP significantly improved in the sudden hearing loss group compared to the groups with other etiologies (p=0.045). The elderly group had more comorbidities than that in the younger adult group (p=0.026), but there were no significant differences in postoperative complications and hospitalization periods.

CONCLUSIONS

While speech recognition and CAP scores were relatively lower in the elderly group compared to the younger adults, the elderly group showed significant improvements in audiological results after CI. Moreover, CI was safe and well tolerated in elderly patients.

Effect of Healthy Aging and Gender on Syntactic Input Processing: A P600 Event-Related Potential Study

PURPOSE

This study aimed to investigate the effect of healthy aging and gender, as well as the interaction, thereof, on syntactic input processing during sentence comprehension. This was achieved through the recording of the P600 event-related potential.

METHOD

Sixty Flemish (native speakers of Dutch) participants (30 men and 30 women), equally distributed into three age groups (young, middle-aged, and older adults), were subjected to a visually presented word order violation task under simultaneous electro-encephalography recording. The task contained 60 sentences, of which half were grammatical and half contained a word order violation. P600 responses were analyzed for amplitude, latency, topographical distribution, and source localization.

RESULTS

Regarding the effect of healthy aging, no age-related differences were found for the amplitude, onset latency, and topographical distribution of the P600 effect (difference wave). Although aging effects on the P600 effect amplitude were absent, a reduced P600 amplitude in response to both the grammatical and ungrammatical sentences was found, next to a reduced overall degree of source activation in linguistic regions of interest. Also, a reduced behavioral accuracy in response to the word order violation was observed in the older adults group. Regarding the effect of gender, females exhibited a larger P600 effect amplitude and a reduced behavioral accuracy compared to males. No gender-related differences were found for P600 effect onset latency, topographical distribution, and source activation.

CONCLUSIONS

While this study demonstrates no effect of aging on the P600 effect, the lower behavioral response and absence of any activation shift argues against functional compensation. Moreover, although increased neural activation in women combined with their reduced behavioral accuracy may indicate the use of different cognitive strategies in men and women, source localization analysis could not objectify this hypothesis.

Effects of aging on cortical representations of continuous speech

Understanding speech in a noisy environment is crucial in day-to-day interactions and yet becomes more challenging with age, even for healthy aging. Age-related changes in the neural mechanisms that enable speech-in-noise listening have been investigated previously; however, the extent to which age affects the timing and fidelity of encoding of target and interfering speech streams is not well understood. Using magnetoencephalography (MEG), we investigated how continuous speech is represented in auditory cortex in the presence of interfering speech in younger and older adults. Cortical representations were obtained from neural responses that time-locked to the speech envelopes with speech envelope reconstruction and temporal response functions (TRFs). TRFs showed three prominent peaks corresponding to auditory cortical processing stages: early (∼50 ms), middle (∼100 ms), and late (∼200 ms). Older adults showed exaggerated speech envelope representations compared with younger adults. Temporal analysis revealed both that the age-related exaggeration starts as early as ∼50 ms and that older adults needed a substantially longer integration time window to achieve their better reconstruction of the speech envelope. As expected, with increased speech masking envelope reconstruction for the attended talker decreased and all three TRF peaks were delayed, with aging contributing additionally to the reduction. Interestingly, for older adults the late peak was delayed, suggesting that this late peak may receive contributions from multiple sources. Together these results suggest that there are several mechanisms at play compensating for age-related temporal processing deficits at several stages but which are not able to fully reestablish unimpaired speech perception.NEW & NOTEWORTHY We observed age-related changes in cortical temporal processing of continuous speech that may be related to older adults' difficulty in understanding speech in noise. These changes occur in both timing and strength of the speech representations at different cortical processing stages and depend on both noise condition and selective attention. Critically, their dependence on noise condition changes dramatically among the early, middle, and late cortical processing stages, underscoring how aging differentially affects these stages.

Neuropsychological Functions and Audiological Findings in Elderly Cochlear Implant Users: The Role of Attention in Postoperative Performance

Objectives: The present study aimed to investigate in a group of elderly CI users working memory and attention, conventionally considered as predictors of better CI performance and to try to disentangle the effects of these cognitive domains on speech perception, finding potential markers of cognitive decline related to audiometric findings. Methods Thirty postlingually deafened CI users aged >60 underwent an audiological evaluation followed by a cognitive assessment of attention and verbal working memory. A correlation analysis was performed to evaluate the associations between cognitive variables while a simple regression investigated the relationships between cognitive and audiological variables. Comparative analysis was performed to compare variables on the basis of subjects’ attention performance. Results: Attention was found to play a significant role in sound field and speech perception. Univariate analysis found a significant difference between poor and high attention performers, while regression analysis showed that attention significantly predicted recognition of words presented at Signal/Noise +10. Further, the high attention performers showed significantly higher scores than low attentional performers for all working memory tasks. Conclusion: Overall findings confirmed that a better cognitive performance may positively contribute to better speech perception outcomes, especially in complex listening situations. WM may play a crucial role in storage and processing of auditory-verbal stimuli and a robust attention may lead to better performance for speech perception in noise. Implementation of cognitive training in auditory rehabilitation of CI users should be investigated in order to improve cognitive and audiological performance in elderly CI users.

Language Network Dysfunction and Formal Thought Disorder in Schizophrenia

BACKGROUND

Pathophysiological inquiries into schizophrenia require a consideration of one of its most defining features: disorganization and impoverishment in verbal behavior. This feature, often captured using the term Formal Thought Disorder (FTD), still remains to be one of the most poorly understood and understudied dimensions of schizophrenia. In particular, the large-scale network level dysfunction that contributes to FTD remains obscure to date.

STUDY DESIGN

In this narrative review, we consider the various challenges that need to be addressed for us to move towards mapping FTD (construct) to a brain network level account (circuit).

STUDY RESULTS

The construct-to-circuit mapping goal is now becoming more plausible than it ever was, given the parallel advent of brain stimulation and the tools providing objective readouts of human speech. Notwithstanding this, several challenges remain to be overcome before we can decisively map the neural basis of FTD. We highlight the need for phenotype refinement, robust experimental designs, informed analytical choices, and present plausible targets in and beyond the Language Network for brain stimulation studies in FTD.

CONCLUSIONS

Developing a therapeutically beneficial pathophysiological model of FTD is a challenging endeavor, but holds the promise of improving interpersonal communication and reducing social disability in schizophrenia. Addressing the issues raised in this review will be a decisive step in this direction.

Task Demands and Sentence Reading Comprehension among Healthy Older Adults: The Complementary Roles of Cognitive Reserve and Working Memory

Ageing entails different functional brain changes. Education, reading experience, and leisure activities, among others, might contribute to the maintenance of cognitive performance among older adults and are conceptualised as proxies for cognitive reserve. However, ageing also conveys a depletion of working memory capacity, which adversely impacts language comprehension. This study investigated how cognitive reserve proxies and working memory jointly predict the performance of healthy older adults in a sentence reading comprehension task, and how their predictive value changes depending on sentence structure and task demands. Cognitively healthy older adults (n = 120) completed a sentence–picture verification task under two conditions: concurrent viewing of the sentence and picture or their sequential presentation, thereby imposing greater demands on working memory. They also completed a questionnaire on cognitive reserve proxies as well as a verbal working memory test. The sentence structure was manipulated by altering the canonical word order and modifying the amount of propositional information. While the cognitive reserve was the main predictor in the concurrent condition, the predictive role of working memory increased under the sequential presentation, particularly for complex sentences. These findings highlight the complementary roles played by cognitive reserve and working memory in the reading comprehension of older adults.

Neural tracking of linguistic and acoustic speech representations decreases with advancing age

BACKGROUND

Older adults process speech differently, but it is not yet clear how aging affects different levels of processing natural, continuous speech, both in terms of bottom-up acoustic analysis and top-down generation of linguistic-based predictions. We studied natural speech processing across the adult lifespan via electroencephalography (EEG) measurements of neural tracking.

GOALS

Our goals are to analyze the unique contribution of linguistic speech processing across the adult lifespan using natural speech, while controlling for the influence of acoustic processing. Moreover, we also studied acoustic processing across age. In particular, we focus on changes in spatial and temporal activation patterns in response to natural speech across the lifespan.

METHODS

52 normal-hearing adults between 17 and 82 years of age listened to a naturally spoken story while the EEG signal was recorded. We investigated the effect of age on acoustic and linguistic processing of speech. Because age correlated with hearing capacity and measures of cognition, we investigated whether the observed age effect is mediated by these factors. Furthermore, we investigated whether there is an effect of age on hemisphere lateralization and on spatiotemporal patterns of the neural responses.

RESULTS

Our EEG results showed that linguistic speech processing declines with advancing age. Moreover, as age increased, the neural response latency to certain aspects of linguistic speech processing increased. Also acoustic neural tracking (NT) decreased with increasing age, which is at odds with the literature. In contrast to linguistic processing, older subjects showed shorter latencies for early acoustic responses to speech. No evidence was found for hemispheric lateralization in neither younger nor older adults during linguistic speech processing. Most of the observed aging effects on acoustic and linguistic processing were not explained by age-related decline in hearing capacity or cognition. However, our results suggest that the effect of decreasing linguistic neural tracking with advancing age at word-level is also partially due to an age-related decline in cognition than a robust effect of age.

CONCLUSION

Spatial and temporal characteristics of the neural responses to continuous speech change across the adult lifespan for both acoustic and linguistic speech processing. These changes may be traces of structural and/or functional change that occurs with advancing age.

Multidimensional inhibitory signatures of sentential negation in behavioral variant frontotemporal dementia

BACKGROUND

Processing of linguistic negation has been associated to inhibitory brain mechanisms. However, no study has tapped this link via multimodal measures in patients with core inhibitory alterations, a critical approach to reveal direct neural correlates and potential disease markers.

METHODS

Here we examined oscillatory, neuroanatomical, and functional connectivity signatures of a recently reported Go/No-go negation task in healthy controls and behavioral variant frontotemporal dementia (bvFTD) patients, typified by primary and generalized inhibitory disruptions. To test for specificity, we also recruited persons with Alzheimer's disease (AD), a disease involving frequent but nonprimary inhibitory deficits.

RESULTS

In controls, negative sentences in the No-go condition distinctly involved frontocentral delta (2-3 Hz) suppression, a canonical inhibitory marker. In bvFTD patients, this modulation was selectively abolished and significantly correlated with the volume and functional connectivity of regions supporting inhibition (e.g. precentral gyrus, caudate nucleus, and cerebellum). Such canonical delta suppression was preserved in the AD group and associated with widespread anatomo-functional patterns across non-inhibitory regions.

DISCUSSION

These findings suggest that negation hinges on the integrity and interaction of spatiotemporal inhibitory mechanisms. Moreover, our results reveal potential neurocognitive markers of bvFTD, opening a new agenda at the crossing of cognitive neuroscience and behavioral neurology.

Decreased Modulation of Population Correlations in Auditory Cortex Is Associated with Decreased Auditory Detection Performance in Old Mice

Age-related hearing loss (presbycusis) affects one-third of the world's population. One hallmark of presbycusis is difficulty hearing in noisy environments. Presbycusis can be separated into two components: the aging ear and the aging brain. To date, the role of the aging brain in presbycusis is not well understood. Activity in the primary auditory cortex (A1) during a behavioral task is because of a combination of responses representing the acoustic stimuli, attentional gain, and behavioral choice. Disruptions in any of these aspects can lead to decreased auditory processing. To investigate how these distinct components are disrupted in aging, we performed in vivo 2-photon Ca2+ imaging in both male and female mice (Thy1-GCaMP6s × CBA/CaJ mice) that retain peripheral hearing into old age. We imaged A1 neurons of young adult (2-6 months) and old mice (16-24 months) during a tone detection task in broadband noise. While young mice performed well, old mice performed worse at low signal-to-noise ratios. Calcium imaging showed that old animals have increased prestimulus activity, reduced attentional gain, and increased noise correlations. Increased correlations in old animals exist regardless of cell tuning and behavioral outcome, and these correlated networks exist over a much larger portion of cortical space. Neural decoding techniques suggest that this prestimulus activity is predictive of old animals making early responses. Together, our results suggest a model in which old animals have higher and more correlated prestimulus activity and cannot fully suppress this activity, leading to the decreased representation of targets among distracting stimuli.SIGNIFICANCE STATEMENT Aging inhibits the ability to hear clearly in noisy environments. We show that the aging auditory cortex is unable to fully suppress its responses to background noise. During an auditory behavior, fewer neurons were suppressed in the old relative to young animals, which leads to higher prestimulus activity and more false alarms. We show that this excess activity additionally leads to increased correlations between neurons, reducing the amount of relevant stimulus information in the auditory cortex. Future work identifying the lost circuits that are responsible for proper background suppression could provide new targets for therapeutic strategies to preserve auditory processing ability into old age.

Structural MRI-Based Measures of Accelerated Brain Aging do not Moderate the Acute Antidepressant Response in Late-Life Depression

OBJECTIVE

Late-life depression (LLD) is characterized by accelerated biological aging. Accelerated brain aging, estimated from structural magnetic resonance imaging (sMRI) data by a machine learning algorithm, is associated with LLD diagnosis, poorer cognitive performance, and disability. We hypothesized that accelerated brain aging moderates the antidepressant response.

DESIGN AND INTERVENTIONS

Following MRI, participants entered an 8-week randomized, controlled trial of escitalopram. Nonremitting participants then entered an open-label 8-week trial of bupropion.

PARTICIPANTS

Ninety-five individuals with LLD.

MEASUREMENTS

A machine learning algorithm estimated each participant's brain age from sMRI data. This was used to calculate the brain-age gap (BAG), or how estimated age differed from chronological age. Secondary sMRI measures of aging pathology included white matter hyperintensity (WMH) volumes and hippocampal volumes. Mixed models examined the relationship between sMRI measures and change in depression severity. Initial analyses tested for a moderating effect of MRI measures on change in depression severity with escitalopram. Subsequent analyses tested for the effect of MRI measures on change in depression severity over time across trials.

RESULTS

In the blinded initial phase, BAG was not significantly associated with a differential response to escitalopram over time. BAG was also not associated with a change in depression severity over time across both arms in the blinded phase or in the subsequent open-label bupropion phase. We similarly did not observe effects of WMH volume or hippocampal volume on change in depression severity over time.

CONCLUSION

sMRI markers of accelerated brain aging were not associated with treatment response in this sequential antidepressant trial.

Hemispheric dissociations in regions supporting auditory sentence comprehension in older adults

We investigated how the aging brain copes with acoustic and syntactic challenges during spoken language comprehension. Thirty-eight healthy adults aged 54 - 80 years (M = 66 years) participated in an fMRI experiment wherein listeners indicated the gender of an agent in short spoken sentences that varied in syntactic complexity (object-relative vs subject-relative center-embedded clause structures) and acoustic richness (high vs low spectral detail, but all intelligible). We found widespread activity throughout a bilateral frontotemporal network during successful sentence comprehension. Consistent with prior reports, bilateral inferior frontal gyrus and left posterior superior temporal gyrus were more active in response to object-relative sentences than to subject-relative sentences. Moreover, several regions were significantly correlated with individual differences in task performance: Activity in right frontoparietal cortex and left cerebellum (Crus I & II) showed a negative correlation with overall comprehension. By contrast, left frontotemporal areas and right cerebellum (Lobule VII) showed a negative correlation with accuracy specifically for syntactically complex sentences. In addition, laterality analyses confirmed a lack of hemispheric lateralization in activity evoked by sentence stimuli in older adults. Importantly, we found different hemispheric roles, with a left-lateralized core language network supporting syntactic operations, and right-hemisphere regions coming into play to aid in general cognitive demands during spoken sentence processing. Together our findings support the view that high levels of language comprehension in older adults are maintained by a close interplay between a core left hemisphere language network and additional neural resources in the contralateral hemisphere.

The Effects of Sustained Literacy Engagement on Cognition and Sentence Processing Among Older Adults

Considerable evidence suggests that language processing depends on memory processes, which are vulnerable to declines with aging. Yet little is known about the effects of language processing in the form of sustained literacy engagement on memory and other aspects of cognition. In the current study, adults (60-79 years of age) were randomly assigned to an 8-week program of leisure reading (n = 38) or to an active puzzle control (n = 38). Relative to the control, the experimental group showed differential improvement in verbal working memory and episodic memory. The experimental group also showed evidence of enhanced conceptual integration in sentence processing. These effects did not vary as a function of personality characteristics (e.g., openness) hypothesized to be compatible with literacy engagement. These findings support the idea that the exercise of cognitive capacities in the context of everyday life may offset age-related impairment in areas of cognition engaged by the activity, regardless of dispositional fit.

Structural Correlates of Overt Sentence Reading in Mild Cognitive Impairment and Mild-to-Moderate Alzheimer's Disease

BACKGROUND

Overt sentence reading in mild cognitive impairment (MCI) and mild-tomoderate Alzheimer's disease (AD) has been associated with slowness of speech, characterized by a higher number of pauses, shorter speech units and slower speech rate and attributed to reduced working memory/ attention and language capacity.

OBJECTIVE

This preliminary case-control study investigates whether the temporal organization of speech is associated with the volume of brain regions involved in overt sentence reading and explores the discriminative ability of temporal speech parameters and standard volumetric MRI measures for the classification of MCI and AD.

METHODS

Individuals with MCI, mild-to-moderate AD, and healthy controls (HC) had a structural MRI scan and read aloud sentences varying in cognitive-linguistic demand (length). The association between speech features and regional brain volumes was examined by linear mixed-effect modeling. Genetic programming was used to explore the discriminative ability of temporal and MRI features.

RESULTS

Longer sentences, slower speech rate, and a higher number of pauses and shorter interpausal units were associated with reduced volumes of the reading network. Speech-based classifiers performed similarly to the MRI-based classifiers for MCI-HC (67% vs. 68%) and slightly better for AD-HC (80% vs. 64%) and AD-MCI (82% vs. 59%). Adding the speech features to the MRI features slightly improved the performance of MRI-based classification for AD-HC and MCI-HC but not HC-MCI.

CONCLUSION

The temporal organization of speech in overt sentence reading reflects underlying volume reductions. It may represent a sensitive marker for early assessment of structural changes and cognitive- linguistic deficits associated with healthy aging, MCI, and AD.

Aging-Related Dissociation of Spatial and Temporal N400 in Sentence-Level Semantic Processing: Evidence From Source Analyses

Age-related differences in sentence-level lexical-semantic processes have been extensively studied, based on the N400 component of event-related potential (ERP). However, there is still a lack of understanding in this regard at the brain-region level. This study explores aging effects on sentence-level semantic processing by comparing the characteristics of the N400 ERP component and brain engagement patterns within individual N400 time windows for two age groups (16 younger adults aged 24.38 ± 3.88 years and 15 older adults aged 67.00 ± 5.04 years) during sentence processing with different plausibility conditions. Our results demonstrated that the N400 effect according to the plausibility condition occurred in different temporal windows in the two age groups, with a delay in the older group. Moreover, it was identified that there was a distinct difference between the groups in terms of the source location of the condition-dependent N400 effect even though no significant difference was derived in its magnitude itself at the sensor-level. Interestingly, the source analysis results indicated that the two groups involved different functional networks to resolve the same semantic violations: the younger group activated the regions corresponding to the typical lexical-semantic network more, whereas the older group recruited the regions belonging to the multiple-demand network more. The findings of this study could be used as a basis for understanding the aging brain in a linguistic context.

What Eye Movement Reveals Concerning Age-Related Dissociation in Syntactic Prediction: Evidence From a Verb-Final Language

PURPOSE

How older adults engage in predictive processing compared to young adults during sentence processing has been a controversial issue in psycholinguistic research. This study investigated whether age-related differences in predictive processing emerge and how they influence young and older adults' construction of sentential representations in a verb-final language using the visual world eye-tracking paradigm.

METHOD

Twenty-five young adults and 24 older adults participated in this study. They were administered a sentence-picture matching task under active and passive conditions during which their eye movements were recorded.

RESULTS

Older adults showed a stronger reliance on predictive processing based on probabilistic constraints compared to young adults at the second noun phrase (NP2) for both active and passive sentences. Specifically, older adults showed significantly greater target advantage looks in actives but greater distractor advantage looks in passives before encountering the verb compared to young adults, revealing older adults' stronger preference for active sentence representations. This stronger predictive processing at the NP2 among older adults engendered greater reduction in fixation proportion on the target picture at the verb only under the passive condition, suggesting that older adults experienced greater difficulties with syntactic revision and integration in passives compared to young adults.

CONCLUSION

The current findings support that older adults more strongly rely on predictive processing based on probabilistic constraints denoted by case markers when constructing sentential representation compared to young adults, and this processing pattern increases processing difficulties when their prediction is incongruent with linguistic input.

Evidence for cortical adjustments to perceptual decision criteria during word recognition in noise

Extensive increases in cingulo-opercular frontal activity are typically observed during speech recognition in noise tasks. This elevated activity has been linked to a word recognition benefit on the next trial, termed "adaptive control," but how this effect might be implemented has been unclear. The established link between perceptual decision making and cingulo-opercular function may provide an explanation for how those regions benefit subsequent word recognition. In this case, processes that support recognition such as raising or lowering the decision criteria for more accurate or faster recognition may be adjusted to optimize performance on the next trial. The current neuroimaging study tested the hypothesis that pre-stimulus cingulo-opercular activity reflects criterion adjustments that determine how much information to collect for word recognition on subsequent trials. Participants included middle-age and older adults (N = 30; age = 58.3 ± 8.8 years; m ± sd) with normal hearing or mild sensorineural hearing loss. During a sparse fMRI experiment, words were presented in multitalker babble at +3 dB or +10 dB signal-to-noise ratio (SNR), which participants were instructed to repeat aloud. Word recognition was significantly poorer with increasing participant age and lower SNR compared to higher SNR conditions. A perceptual decision-making model was used to characterize processing differences based on task response latency distributions. The model showed that significantly less sensory evidence was collected (i.e., lower criteria) for lower compared to higher SNR trials. Replicating earlier observations, pre-stimulus cingulo-opercular activity was significantly predictive of correct recognition on a subsequent trial. Individual differences showed that participants with higher criteria also benefitted the most from pre-stimulus activity. Moreover, trial-level criteria changes were significantly linked to higher versus lower pre-stimulus activity. These results suggest cingulo-opercular cortex contributes to criteria adjustments to optimize speech recognition task performance.

Effects of Leisure Activities on the Cognitive Ability of Older Adults: A Latent Variable Growth Model Analysis

Based on the data of four periods of CLHLS (2008, 2011, 2014, 2018), the latent variable growth model (LGCM) was applied to 2344 older adults who completed four follow-up surveys, to study the trajectory of leisure activities and cognitive ability and explore the relationship between leisure activities and cognitive ability of older adults. The results showed that: (1) leisure activities and cognitive ability of older adults showed a non-linear downward trend; (2) leisure activities significantly and positively predicted the cognitive ability of older adults at every time point; (3) the initial level of leisure activity positively predicted the initial level of cognitive ability but negatively predicted the rate of cognitive decline; In addition, cognitive activities had a greater effect on cognitive ability than non-exercise physical activities; (4) the rate of decline of leisure activities also significantly and positively predicted the rate of decline of cognitive ability; (5) cross-lagged regression analysis further suggested the overall positive predictive effect of leisure activity on cognitive ability; (6) overall, education level had a significant contribution to cognitive ability, and the higher the education level, the slower the decline of cognitive ability; and (7) smoking could promote cognitive ability in older adults and no significant effect was found between alcohol drinking and cognitive ability. Accordingly, the government should encourage older adults to do more leisure activities, especially the cognitive activity, to effectively prevent cognitive decline.

Gender-specific associations of speech-frequency hearing loss, high-frequency hearing loss, and cognitive impairment among older community dwellers in China

Background and Aims

This study aimed atinvestigating the relationship between speech-frequency hearing loss (SFHL), high-frequency hearing loss (HFHL), and cognitive impairment (CI) and then to determine whether there are any differences in gender among older community dwellers in China.

Methods

1012 adults aged ≥ 60 years (428 males; average age, 72.61 ± 5.51 years) and living in Chongming District, Shanghai were enrolled in the study. We used the audiometric definition of hearing loss (HL) adopted by the World Health Organization (WHO). Speech-frequencies were measured at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz; high-frequencies were measured at 4 kHz and 8 kHz. Pure tone average (PTA) was measured as hearing sensitivity. Cognitive performance was measured using the mini mental state examination (MMSE).

Results

Our studies demonstrated a 37.6% prevalence of HL in males and a 36.0% prevalence of HL in females. Adjusted for confounding variables, the results from a multivariate analysis showed that SFHL was associated with CI in females (OR = 2.922, 95% Confidence Interval = 1.666–5.124) and males (OR = 2.559, 95% Confidence Interval = 1.252–5.232). However, HFHL was associated with CI only in females (OR = 3.490, 95% Confidence Interval = 1.834–6.643). HL was associated with poorer cognitive scores (P < 0.05). “Registration” (P < 0.05) in MMSE was associated with speech- and high-frequency hearing sensitivity.

Conclusions

The associations between HL and CI varied according to gender in older community-dwellers, suggesting that different mechanisms are involved in the etiology of HL. Moreover, hearing sensitivity was negatively associated with cognition scores; therefore, early screening for HL and CI among older community-dwelling adults is advised.

The Laterality of Early Age-Related Hearing Loss and Brain β-Amyloid

OBJECTIVE

Worse hearing was linked to higher brain β-amyloid, a pathologic hallmark of Alzheimer's disease, in a recent study. We analyze the associations between β-amyloid and early age-related hearing loss in the right versus left ear to explore the laterality of this relationship.

STUDY DESIGN

Cross-sectional analysis of a prospective cohort study.

SETTING

Tertiary referral center.

PARTICIPANTS

Ninety-eight late middle-age adults.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The primary outcome was whole brain and regional β-amyloid standardized uptake value ratio (SUVR) on positron emission tomography. The exposure was hearing in the right and left ear, measured by pure tone average (PTA) and word recognition score (WRS). Linear regression analyzed the association between β-amyloid and hearing in each ear, adjusting for potential confounders, including age, gender, education, cardiovascular disease, and hearing aid use.

RESULTS

Mean age ± standard deviation was 64.3 ± 3.5 years. Mean PTA was 20.4 ± 8.8 dB. Multivariable regression adjusting for covariates demonstrated that a 10 dB worsening in PTA in the left ear was associated with significantly higher β-amyloid (SUVR) in the bilateral cingulate gyri (right coefficient: 0.029 [95% confidence interval: 0.003-0.054]; left: 0.029 [0.003-0.055]), bilateral frontal lobes (right: 0.024 [0.002-0.047]; left: 0.028 [0.006-0.049]), and the right temporal lobe (0.019 [0.002-0.037]). Consistent results were observed when WRS served as the exposure. No associations were observed between β-amyloid and PTA or WRS in the right ear.

CONCLUSIONS

Worse hearing in the left ear, but not the right ear, was associated with higher β-amyloid. This might relate to asymmetric central auditory processing.

Intrinsic Brain Activity of Inferior Temporal Region Increased in Prodromal Alzheimer's Disease With Hearing Loss

Background and Objective

Hearing loss (HL) is one of the modifiable risk factors for Alzheimer's disease (AD). However, the underlying mechanism behind HL in AD remains elusive. A possible mechanism is cognitive load hypothesis, which postulates that over-processing of degraded auditory signals in the auditory cortex leads to deficits in other cognitive functions. Given mild cognitive impairment (MCI) is a prodromal stage of AD, untangling the association between HL and MCI might provide insights for potential mechanism behind HL.

Methods

We included 85 cognitively normal (CN) subjects with no hearing loss (NHL), 24 CN with HL, 103 mild cognitive impairment (MCI) patients with NHL, and 23 MCI with HL from the ADNI database. All subjects underwent resting-state functional MRI and neuropsychological scale assessments. Fractional amplitude of low-frequency fluctuation (fALFF) was used to reflect spontaneous brain activity. The mixed-effects analysis was applied to explore the interactive effects between HL and cognitive status (GRF corrected, voxel p-value <0.005, cluster p-value < 0.05, two-tailed). Then, the FDG data was included to further reflect the regional neuronal abnormalities. Finally, Pearson correlation analysis was performed between imaging metrics and cognitive scores to explore the clinical significance (Bonferroni corrected, p < 0.05).

Results

The interactive effects primarily located in the left superior temporal gyrus (STG) and bilateral inferior temporal gyrus (ITG). Post-hoc analysis showed that NC with HL had lower fALFF in bilateral ITG compared to NC with NHL. NC with HL had higher fALFF in the left STG and decreased fALFF in bilateral ITG compared to MCI with HL. In addition, NC with HL had lower fALFF in the right ITG compared to MCI with NHL. Correlation analysis revealed that fALFF was associated with MMSE and ADNI-VS, while SUVR was associated with MMSE, MoCA, ADNI-EF and ADNI-Lan.

Conclusion

HL showed different effects on NC and MCI stages. NC had increased spontaneous brain activity in auditory cortex while decreased activity in the ITG. Such pattern altered with disease stage changing and manifested as decreased activity in auditory cortex along with increased activity in ITG in MCI. This suggested that the cognitive load hypothesis may be the underlying mechanism behind HL.

Is Old Age Just a Number in Language Skills? Language Performance and Its Relation to Age, Education, Gender, Cognitive Screening, and Dentition in Very Old Finnish Speakers

PURPOSE

This study reports on how very old (VO) Finnish people without dementia perform in the Western Aphasia Battery (WAB) and two verbal fluency tasks and which demographic factors predict the performance.

METHOD

The study included fifty 80- to 100-year-old community-dwelling Finnish speakers with no dementing illnesses or speech-language disabilities, who completed the WAB and two verbal fluency tasks. Multifactorial statistical analyses with recursive partitioning were carried out to determine the significant predictors out of five predictor variables (age, gender, education, dentition, and Mini-Mental State Examination [MMSE]) for four response variables (WAB Aphasia Quotient [AQ], Language Quotient [LQ], semantic, and phonemic word fluencies).

RESULTS

Overall, individual variation was notable in VO speakers. All predictor variables were statistically significantly associated with one or more of the language skills. Age was the most significant predictor; the critical age of 85-86 years was associated with a decline in WAB-AQ and semantic fluency. Poor dentition and the MMSE score both predicted a decline in WAB-LQ and phonemic fluency. A high level of education was positively associated with the skills of the best-performing individuals in WAB-AQ, WAB-LQ, and semantic fluency.

CONCLUSIONS

VO age is a significant factor contributing to language performance. However, a younger age, a good cognitive performance, intact teeth, and a higher educational level also seem to have a preservative power as regards language skills. Gender differences should be interpreted with caution. The results of this study provide culture- and language-specific normative data, which aids in differentiating typical aging from the signs of acute or degenerative neuropathology to ensure appropriate medical and therapeutic interventions.

Differences in Diffusion Tensor Imaging White Matter Integrity Related to Verbal Fluency Between Young and Old Adults

Throughout adulthood, the brain undergoes an array of structural and functional changes during the typical aging process. These changes involve decreased brain volume, reduced synaptic density, and alterations in white matter (WM). Although there have been some previous neuroimaging studies that have measured the ability of adult language production and its correlations to brain function, structural gray matter volume, and functional differences between young and old adults, the structural role of WM in adult language production in individuals across the life span remains to be thoroughly elucidated. This study selected 38 young adults and 35 old adults for diffusion tensor imaging (DTI) and performed the Controlled Oral Word Association Test to assess verbal fluency (VF). Tract-Based Spatial Statistics were employed to evaluate the voxel-based group differences of diffusion metrics for the values of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and local diffusion homogeneity (LDH) in 12 WM regions of interest associated with language production. To investigate group differences on each DTI metric, an analysis of covariance (ANCOVA) controlling for sex and education level was performed, and the statistical threshold was considered at p < 0.00083 (0.05/60 labels) after Bonferroni correction for multiple comparisons. Significant differences in DTI metrics identified in the ANCOVA were used to perform correlation analyses with VF scores. Compared to the old adults, the young adults had significantly (1) increased FA values on the bilateral anterior corona radiata (ACR); (2) decreased MD values on the right ACR, but increased MD on the left uncinate fasciculus (UF); and (3) decreased RD on the bilateral ACR. There were no significant differences between the groups for AD or LDH. Moreover, the old adults had only a significant correlation between the VF score and the MD on the left UF. There were no significant correlations between VF score and DTI metrics in the young adults. This study adds to the growing body of research that WM areas involved in language production are sensitive to aging.

How the healthy ageing brain supports semantic binding during language comprehension

Semantic binding refers to constructing complex meaning based on elementary building blocks. Using electroencephalography (EEG), we investigated the age-related changes in modulations of oscillatory brain activity supporting lexical retrieval and semantic binding. Young and older adult participants were visually presented two-word phrases, which for the first word revealed a lexical retrieval signature (e.g., swift vs. swrfeq) and for the second word revealed a semantic binding signature (e.g., horse in a semantic binding "swift horse" vs. no binding "swrfeq horse" context). The oscillatory brain activity associated with lexical retrieval as well as semantic binding significantly differed between healthy older and young adults. Specifically for lexical retrieval, we found that different age groups exhibited opposite patterns of theta and alpha modulation, which as a combined picture suggest that lexical retrieval is associated with different and delayed signatures in older compared with young adults. For semantic binding, in young adults, we found a signature in the low-beta range centred around the target word onset (i.e., a smaller low-beta increase for binding relative to no binding), whereas in healthy older adults, we found an opposite binding signature about ~500 ms later in the low- and high-beta range (i.e., a smaller low- and high-beta decrease for binding relative to no binding). The novel finding of a different and delayed oscillatory signature for semantic binding in healthy older adults reflects that the integration of word meaning into the semantic context takes longer and relies on different mechanisms in healthy older compared with young adults.

Dedifferentiation of Functional Brain Activation Associated With Greater Visual Discrimination Accuracy in Middle-Aged and Older Adults

Neural dedifferentiation refers to an age-related phenomenon whereby brain functions that are localized to specific, distinct, and differentiated brain areas in young adults become less so as people reach more advanced age. Older adults tend to exhibit greater spread of cortical activation on fMRI during cognitive processing compared to younger adults, with evidence that this occurs during visuoperceptual processing. Some age-related functional changes are considered compensatory, but whether dedifferentiation is compensatory is not clearly understood. The current study assessed dedifferentiation and visual discrimination performance during simultaneous match-to-sample tasks from the Visual Assessment Battery (VAB) among 40 healthy middle-aged and older adults using fMRI. Task-relevant regions of interest (ROIs) were created in the dorsal stream for discrimination of spatial location, the ventral stream for shape, and an area encompassing V5 for velocity. Dedifferentiation, or less specificity in functional activation, was associated with greater discrimination accuracy and more years of education. Secondary analyses showed that reduced functional activation in task-relevant ROIs was associated with faster discrimination speed. Age was unassociated with functional activation. Results suggest that dedifferentiation is compensatory. Lack of age effects suggest that other factors beyond age, such as cognitive or brain reserve, may better predict performance when considering cognitive skills that are relatively stable as adults age, such as visual discrimination.

Age-preserved semantic memory and the CRUNCH effect manifested as differential semantic control networks: An fMRI study

Semantic memory representations are overall well-maintained in aging whereas semantic control is thought to be more affected. To explain this phenomenon, this study aims to test the predictions of the Compensation Related Utilization of Neural Circuits Hypothesis (CRUNCH) focusing on task demands in aging as a possible framework. The CRUNCH effect would manifest itself in semantic tasks through a compensatory increase in neural activation in semantic control network regions but only up to a certain threshold of task demands. This study will compare 40 young (20-35 years old) with 40 older participants (60-75 years old) in a triad-based semantic judgment task performed in an fMRI scanner while manipulating levels of task demands (low vs. high) through semantic distance. In line with the CRUNCH predictions, differences in neurofunctional activation and behavioral performance (accuracy and response times) are expected in young vs. old participants in the low- vs. high-demand conditions manifested in semantic control Regions of Interest.

Age-related hearing loss and cognitive decline: MRI and cellular evidence

Extensive evidence supports the association between age-related hearing loss (ARHL) and cognitive decline. It is, however, unknown whether a causal relationship exists between these two, or whether they both result from shared mechanisms. This paper intends to study this relationship through a comprehensive review of MRI findings as well as evidence of cellular alterations. Our review of structural MRI studies demonstrates that ARHL is independently linked to accelerated atrophy of total and regional brain volumes and reduced white matter integrity. Resting-state and task-based fMRI studies on ARHL also show changes in spontaneous neural activity and brain functional connectivity; and alterations in brain areas supporting auditory, language, cognitive, and affective processing independent of age, respectively. Although MRI findings support a causal relationship between ARHL and cognitive decline, the contribution of potential shared mechanisms should also be considered. In this regard, the review of cellular evidence indicates their role as possible common mechanisms underlying both age-related changes in hearing and cognition. Considering existing evidence, no single hypothesis can explain the link between ARHL and cognitive decline, and the contribution of both causal (i.e., the sensory hypothesis) and shared (i.e., the common cause hypothesis) mechanisms is expected.

Systematic Comparison of Trial Exclusion Criteria for Pupillometry Data Analysis in Individuals With Single-Sided Deafness and Normal Hearing

The measurement of pupil dilation has become a common way to assess listening effort. Pupillometry data are subject to artifacts, requiring highly contaminated data to be discarded from analysis. It is unknown how trial exclusion criteria impact experimental results. The present study examined the effect of a common exclusion criterion, percentage of blinks, on speech intelligibility and pupil dilation measures in 9 participants with single-sided deafness (SSD) and 20 participants with normal hearing. Participants listened to and repeated sentences in quiet or with speech maskers. Pupillometry trials were processed using three levels of blink exclusion criteria: 15%, 30%, and 45%. These percentages reflect a threshold for missing data points in a trial, where trials that exceed the threshold are excluded from analysis. Results indicated that pupil dilation was significantly greater and intelligibility was significantly lower in the masker compared with the quiet condition for both groups. Across-group comparisons revealed that speech intelligibility in the SSD group decreased significantly more than the normal hearing group from quiet to masker conditions, but the change in pupil dilation was similar for both groups. There was no effect of blink criteria on speech intelligibility or pupil dilation results for either group. However, the total percentage of blinks in the masker condition was significantly greater than in the quiet condition for the SSD group, which is consistent with previous studies that have found a relationship between blinking and task difficulty. This association should be carefully considered in future experiments using pupillometry to gauge listening effort.

Social factors may mediate the relationship between subjective age-related hearing loss and episodic memory

Objectives: To investigate whether the relationship between subjective age-related hearing loss (SARHL) and episodic memory functioning is mediated by measures of social functioning.Methods: Using data from 8,163 adults over 50 that participated in the Irish Longitudinal Study of Ageing (three waves, each two years apart), we used a multiple mediation model within a Structural Equation Modelling framework to explore potential social mediators of the relationship between SARHL and episodic memory functioning, controlling for demographic and health covariates.Results: Neither the direct effect of self-reported hearing difficulties on memory functioning (β = -.03), nor the total effect (β = .01), were significant. A small inconsistent indirect effect of self-reported hearing difficulties on episodic memory via weekly social activity engagement (β = -.002) was found.Conclusions: Self-reported hearing difficulties may exert an indirect effect on episodic memory via weekly social activity engagement. The findings may have implications for identification of individuals at risk of memory decline in later life.

Tinnitus and Neuropsychological Dysfunction in the Elderly: A Systematic Review on Possible Links

INTRODUCTION

Tinnitus is a common and disabling symptom often associated with hearing loss. While clinical practice frequently shows that a certain degree of psychological discomfort often characterizes tinnitus suffers, it has been recently suggested in adults as a determining factor for cognitive decline affecting attention and memory domains. The aim of our systematic review was to provide evidence for a link between tinnitus, psychological distress, and cognitive dysfunction in older patients and to focus on putative mechanisms of this relationship.

METHODS

We performed a systematic review, finally including 192 articles that were screened. This resulted in 12 manuscripts of which the full texts were included in a qualitative analysis.

RESULTS

The association between tinnitus and psychological distress, mainly depression, has been demonstrated in older patients, although only few studies addressed the aged population. Limited studies on cognitive dysfunction in aged patients affected by chronic tinnitus are hardly comparable, as they use different methods to validate cognitive impairment. Actual evidence does not allow us with certainty to establish if tinnitus matters as an independent risk factor for cognitive impairment or evolution to dementia.

CONCLUSION

Tinnitus, which is usually associated with age-related hearing loss, might negatively affect emotional wellbeing and cognitive capacities in older people, but further studies are required to improve the evidence.

Age-Related Hearing Loss and the Development of Cognitive Impairment and Late-Life Depression: A Scoping Overview

Age-related hearing loss (ARHL) has been connected to both cognitive decline and late-life depression. Several mechanisms have been offered to explain both individual links. Causal and common mechanisms have been theorized for the relationship between ARHL and impaired cognition, including dementia. The causal mechanisms include increased cognitive load, social isolation, and structural brain changes. Common mechanisms include neurovascular disease as well as other known or as-yet undiscovered neuropathologic processes. Behavioral mechanisms have been used to explain the potentially causal association of ARHL with depression. Behavioral mechanisms include social isolation, loneliness, as well as decreased mobility and impairments of activities of daily living, all of which can increase the risk of depression. The mechanisms underlying the associations between hearing loss and impaired cognition, as well as hearing loss and depression, are likely not mutually exclusive. ARHL may contribute to both impaired cognition and depression through overlapping mechanisms. Furthermore, ARHL may contribute to impaired cognition which may, in turn, contribute to depression. Because ARHL is highly prevalent and greatly undertreated, targeting this condition is an appealing and potentially influential strategy to reduce the risk of developing two potentially devastating diseases of later life. However, further studies are necessary to elucidate the mechanistic relationship between ARHL, depression, and impaired cognition.

Noise Damage Accelerates Auditory Aging and Tinnitus: A Canadian Population-Based Study

OBJECTIVE

Age-related hearing loss (ARHL) is the third most challenging disability in older adults. Noise is a known modifiable risk factor of ARHL, which can drive adverse health effects. Few large-scale studies, however, have shown how chronic noise exposure (CNE) impacts the progression of ARHL and tinnitus.

STUDY DESIGN

Retrospective large-scale study.

SETTING

Audiology clinical practice.

PATIENTS

In this study, 928 individuals aged 30-100 years without (n=497) or with the experience of CNE (n=431) were compared in their hearing assessments and tinnitus. In order to only investigate the impact of CNE on ARHL and tinnitus, people with other risk factors of hearing loss were excluded from the study.

INTERVENTION

Diagnostic.

MAIN OUTCOME MEASURES

Noise damage was associated with a greater ARHL per age decades (pure-tone average(PTA)0.5-4kHz alterations 19.6-70.8 dB vs. 8.0-63.2 dB, ≤0.001), an acceleration of developing a significant ARHL at least by two decades (PTA0.5-4kHz 33.4 dB at 50-59yr vs. 28.2 dB at 30-39yr, ≤0.001), and an increased loss of word recognition scores (total average 84.7% vs. 80.0%, ≤0.001). Significant noise-associated growth in the prevalence of tinnitus also was shown, including more than a triple prevalence for constant tinnitus (28.10% vs. 8.85%, ≤0.001) and near to a double prevalence for intermittent tinnitus (19.10% vs. 11.10%, ≤0.001). Noise also resulted in the elevation of the static compliance of the tympanic membrane throughout age (total average 0.61 vs. 0.85 mmho, ≤0.001).

CONCLUSIONS

Our findings emphasize the significant contribution of CNE in auditory aging and the precipitation of both ARHL and tinnitus.

Congenital Hearing Loss Is Associated With a High Incidence of Central Nervous System Abnormalities

OBJECTIVE(S)

To assess the incidence of central nervous system abnormalities in pediatric subjects with sensorineural hearing loss (SNHL).

METHODS

One hundred forty-three pediatric subjects evaluated for SNHL at a single academic center from 2007 to 2014 were included and divided into eight diagnosis groups based on etiology of SNHL. One hundred forty-three age- and gender-matched control subjects with no known brain-related pathology or history of hearing loss were included as healthy controls for comparison. Two neuroradiologists independently evaluated magnetic resonance imaging (MRI) and computed tomography (CT) scans for each subject. Comparison of abnormal cerebral development was performed using an ordinal logistic regression model. Concordance between CT and MRI of the temporal bone was assessed using the kappa statistic.

RESULTS

The etiologies of hearing loss in our cohort were 37.8% genetic, 12.6% infectious, 1.4% ototoxin-induced, and 48.3% idiopathic. Brain MRI revealed cerebral developmental abnormalities in defined regions in >30% of the SNHL cohort, significantly more than in normal-hearing pediatric controls. The Sylvian fissure, Virchow-Robin spaces, and lateral ventricles were most commonly affected. In the temporal bone, the percentage of subjects with concordant findings on CT and MRI was ≥92% across all anatomical structures.

CONCLUSION

MRI revealed a high incidence of intracranial abnormalities, suggestive of aberrant development of auditory and nonauditory neural structures associated with SNHL. CT and MRI share a high degree of concordance in detecting temporal bone anomalies. Inclusion of MRI as part of the workup of congenital SNHL may facilitate the detection of developmental anomalies of the brain associated with SNHL.

Dissociable electrophysiological measures of natural language processing reveal differences in speech comprehension strategy in healthy ageing

Healthy ageing leads to changes in the brain that impact upon sensory and cognitive processing. It is not fully clear how these changes affect the processing of everyday spoken language. Prediction is thought to play an important role in language comprehension, where information about upcoming words is pre-activated across multiple representational levels. However, evidence from electrophysiology suggests differences in how older and younger adults use context-based predictions, particularly at the level of semantic representation. We investigate these differences during natural speech comprehension by presenting older and younger subjects with continuous, narrative speech while recording their electroencephalogram. We use time-lagged linear regression to test how distinct computational measures of (1) semantic dissimilarity and (2) lexical surprisal are processed in the brains of both groups. Our results reveal dissociable neural correlates of these two measures that suggest differences in how younger and older adults successfully comprehend speech. Specifically, our results suggest that, while younger and older subjects both employ context-based lexical predictions, older subjects are significantly less likely to pre-activate the semantic features relating to upcoming words. Furthermore, across our group of older adults, we show that the weaker the neural signature of this semantic pre-activation mechanism, the lower a subject’s semantic verbal fluency score. We interpret these findings as prediction playing a generally reduced role at a semantic level in the brains of older listeners during speech comprehension and that these changes may be part of an overall strategy to successfully comprehend speech with reduced cognitive resources.

Association of Hearing Loss with Physical, Social, and Mental Activity Engagement

This article aims to evaluate a hearing loss intervention versus an aging education intervention on activity engagement in the Aging and Cognitive Health Evaluation in Elders pilot (ACHIEVE-P). Forty adults (70-84 years) with hearing loss recruited from the Atherosclerosis Risk in Communities Study and de novo participated. Participants were randomized 1:1 to a best practices hearing intervention or a successful aging intervention. Hearing was measured with pure-tone audiometry. The Community Healthy Activities Model Program for Seniors questionnaire measured self-reported time engaging in activities at baseline and 6-month follow-up. At baseline, greater hearing loss was associated with reduced time per week on mental activities (-3.0 hours per 10 dB of hearing loss, 95% confidence interval: -5.8, -0.2). Mental activity engagement increased (mean: +1.3 hours, SD = 6.6) for the hearing intervention group but decreased (mean: -1.1 hours, SD = 4.8) for the aging education group (Cohen's d : 0.41). Hearing loss may be associated with reduced engagement in mental activities. Whether hearing loss treatment impacts activity will be studied in the full-scale ACHIEVE trial.

Age-related effects on the neural processing of semantic complexity in a continuous narrative: Modulation by gestures already present in young to middle-aged adults

The processing of semantically complex speech is a demanding task which can be facilitated by speech-associated arm and hand gestures. However, the role of age concerning the perception of semantic complexity and the influence of gestures in this context remains unclear. The goal of this study was to investigate if age-related differences are already present in early adulthood during the processing of semantic complexity and gestures. To this end, we analyzed fMRI images of a sample of 38 young and middle-aged participants (age-range: 19-55). They had the task to listen and to watch a narrative. The narrative contained segments varying in the degree of semantic complexity, and they were spontaneously accompanied by gestures. The semantic complexity of the story was measured by the idea density. Consistent with previous findings in young adults, we observed increased activation for passages with lower compared to higher complexity in bilateral temporal areas and the precuneus. BOLD signal in the left frontal and left parietal regions correlated during the perception of complex passages with increasing age. This correlation was reduced for passages presented with gestures. Median-split based post-hoc comparisons confirmed that group differences between younger (19-23 years) and older adults within the early adult lifespan (24-55 years) were significantly reduced in passages with gestures. Our results suggest that older adults within early adulthood adapt to the requirements of highly complex passages activating additional regions when no gesture information is available. Gestures might play a facilitative role with increasing age, especially when speech is complex.

Cognitive reserve and network efficiency as compensatory mechanisms of the effect of aging on phonemic fluency

Compensation in cognitive aging is a topic of recent interest. However, factors contributing to cognitive compensation in functions such as phonemic fluency (PF) are not completely understood. Using cross-sectional data, we investigated cognitive reserve (CR) and network efficiency in young (32-58 years) versus old (59-84 years) individuals with high versus low performance in PF. ANCOVA was used to investigate the interaction between CR, age, and performance in PF. Random forest and graph theory analyses were conducted to study the contribution of cognition to PF and efficiency measures, respectively. Higher CR increased performance in PF and reduced age-related differences in PF. A slightly higher number of cognitive functions contributed to performance in high CR groups. The networks were more integrated in high CR individuals, both in the older age and high-performance groups. The strength and segregation of the networks were decreased in high-performance groups with high CR. We conclude that PF decreases less with age in individuals with higher CR, possibly due to a greater capacity to recruit non-linguistic cognitive networks, and efficient use of language networks, thereby integrating information in a rapid way across less fragmented networks. High CR and network efficiency seem to be important factors for cognitive compensation.

White matter pathways underlying Chinese semantic and phonological fluency in mild cognitive impairment

Neuroimaging evidence has suggested that Chinese-language processing differs from that of its alphabetic-language counterparts. However, the underlying white matter pathway correlations between semantic and phonological fluency in Chinese-language processing remain unknown. Thus, we investigated the differences between two verbal fluency tests on 50 participants with amnestic mild cognitive impairment (aMCI) and 36 healthy controls (HC) with respect to five groups (ventral and dorsal stream fibers, frontal-striatal fibers, hippocampal-related fibers, and the corpus callosum) of white matter microstructural integrity. Diffusion spectrum imaging was used. The results revealed a progressive reduction in advantage in semantic fluency relative to phonological fluency from HC to single-domain aMCI to multidomain aMCI. Common and dissociative white matter correlations between tests of the two types of fluency were identified. Both types of fluency relied on the corpus callosum and ventral stream fibers, semantic fluency relied on the hippocampal-related fibers, and phonological fluency relied on the dorsal stream and frontal-striatal fibers. The involvement of bilateral tracts of interest as well as the association with the corpus callosum indicate the uniqueness of Chinese-language fluency processing. Dynamic associations were noted between white matter tract involvement and performance on the two fluency tests in four time blocks. Overall, our findings suggest the clinical utility of verbal fluency tests in geriatric populations, and they elucidate both task-specific and language-specific brain-behavior associations.