Epigenetic Markers of Aging Predict the Neural Oscillations Serving Selective Attention

Accelerated epigenetic age is associated with whole-brain functional connectivity and impaired cognitive performance in older adults

While chronological age is a strong predictor for health-related risk factors, it is an incomplete metric that fails to fully characterize the unique aging process of individuals with different genetic makeup, neurodevelopment, and environmental experiences. Recent advances in epigenomic array technologies have made it possible to generate DNA methylation-based biomarkers of biological aging, which may be useful in predicting a myriad of cognitive abilities and functional brain network organization across older individuals. It is currently unclear which cognitive domains are negatively correlated with epigenetic age above and beyond chronological age, and it is unknown if functional brain organization is an important mechanism for explaining these associations. In this study, individuals with accelerated epigenetic age (i.e. AgeAccelGrim) performed worse on tasks that spanned a wide variety of cognitive faculties including both fluid and crystallized intelligence (N = 103, average age = 68.98 years, 73 females, 30 males). Additionally, fMRI connectome-based predictive models suggested a mediating mechanism of functional connectivity on epigenetic age acceleration-cognition associations primarily in medial temporal lobe and limbic structures. This research highlights the important role of epigenetic aging processes on the development and maintenance of healthy cognitive capacities and function of the aging brain.

Developmentally sensitive multispectral cortical connectivity profiles serving visual selective attention

Throughout childhood and adolescence, the brain undergoes significant structural and functional changes that contribute to the maturation of multiple cognitive domains, including selective attention. Selective attention is crucial for healthy executive functioning and while key brain regions serving selective attention have been identified, their age-related changes in neural oscillatory dynamics and connectivity remain largely unknown. We examined the developmental sensitivity of selective attention circuitry in 91 typically developing youth aged 6 - 13 years old. Participants completed a number-based Simon task while undergoing magnetoencephalography (MEG) and the resulting data were preprocessed and transformed into the time-frequency domain. Significant oscillatory brain responses were imaged using a beamforming approach, and task-related peak voxels in the occipital, parietal, and cerebellar cortices were used as seeds for subsequent whole-brain connectivity analyses in the alpha and gamma range. Our key findings revealed developmentally sensitive connectivity profiles in multiple regions crucial for selective attention, including the temporoparietal junction (alpha) and prefrontal cortex (gamma). Overall, these findings suggest that brain regions serving selective attention are highly sensitive to developmental changes during the pubertal transition period.

Theta oscillatory dynamics serving cognitive control index psychosocial distress in youth

Background

Psychosocial distress among youth is a major public health issue characterized by disruptions in cognitive control processing. Using the National Institute of Mental Health's Research Domain Criteria (RDoC) framework, we quantified multidimensional neural oscillatory markers of psychosocial distress serving cognitive control in youth.

Methods

The sample consisted of 39 peri-adolescent participants who completed the NIH Toolbox Emotion Battery (NIHTB-EB) and the Eriksen flanker task during magnetoencephalography (MEG). A psychosocial distress index was computed with exploratory factor analysis using assessments from the NIHTB-EB. MEG data were analyzed in the time-frequency domain and peak voxels from oscillatory maps depicting the neural cognitive interference effect were extracted for voxel time series analyses to identify spontaneous and oscillatory aberrations in dynamics serving cognitive control as a function of psychosocial distress. Further, we quantified the relationship between psychosocial distress and dynamic functional connectivity between regions supporting cognitive control.

Results

The continuous psychosocial distress index was strongly associated with validated measures of pediatric psychopathology. Theta-band neural cognitive interference was identified in the left dorsolateral prefrontal cortex (dlPFC) and middle cingulate cortex (MCC). Time series analyses of these regions indicated that greater psychosocial distress was associated with elevated spontaneous activity in both the dlPFC and MCC and blunted theta oscillations in the MCC. Finally, we found that stronger phase coherence between the dlPFC and MCC was associated with greater psychosocial distress.

Conclusions

Greater psychosocial distress was marked by alterations in spontaneous and oscillatory theta activity serving cognitive control, along with hyperconnectivity between the dlPFC and MCC.

Healthy aging alters the oscillatory dynamics and fronto-parietal connectivity serving fluid intelligence

Fluid intelligence (Gf) involves logical reasoning and novel problem-solving abilities. Often, abstract reasoning tasks like Raven's progressive matrices are used to assess Gf. Prior work has shown an age-related decline in fluid intelligence capabilities, and although many studies have sought to identify the underlying mechanisms, our understanding of the critical brain regions and dynamics remains largely incomplete. In this study, we utilized magnetoencephalography (MEG) to investigate 78 individuals, ages 20-65 years, as they completed an abstract reasoning task. MEG data was co-registered with structural MRI data, transformed into the time-frequency domain, and the resulting neural oscillations were imaged using a beamformer. We found worsening behavioral performance with age, including prolonged reaction times and reduced accuracy. MEG analyses indicated robust oscillations in the theta, alpha/beta, and gamma range during the task. Whole brain correlation analyses with age revealed relationships in the theta and alpha/beta frequency bands, such that theta oscillations became stronger with increasing age in a right prefrontal region and alpha/beta oscillations became stronger with increasing age in parietal and right motor cortices. Follow-up connectivity analyses revealed increasing parieto-frontal connectivity with increasing age in the alpha/beta frequency range. Importantly, our findings are consistent with the parieto-frontal integration theory of intelligence (P-FIT). These results further suggest that as people age, there may be alterations in neural responses that are spectrally specific, such that older people exhibit stronger alpha/beta oscillations across the parieto-frontal network during abstract reasoning tasks.

Genome-Wide Integrative Transcriptional Profiling Identifies Age-Associated Signatures in Dogs

Mammals experience similar stages of embryonic development, birth, infancy, youth, adolescence, maturity, and senescence. While embryonic developmental processes have been extensively researched, many molecular mechanisms regulating the different life stages after birth, such as aging, remain unresolved. We investigated the conserved and global molecular transitions in transcriptional remodeling with age in dogs of 15 breeds, which revealed that genes underlying hormone level regulation and developmental programs were differentially regulated during aging. Subsequently, we show that the candidate genes associated with tumorigenesis also exhibit age-dependent DNA methylation patterns, which might have contributed to the tumor state through inhibiting the plasticity of cell differentiation processes during aging, and ultimately suggesting the molecular events that link the processes of aging and cancer. These results highlight that the rate of age-related transcriptional remodeling is influenced not only by the lifespan, but also by the timing of critical physiological milestones.

Epigenetic aging is associated with aberrant neural oscillatory dynamics serving visuospatial processing in people with HIV

BACKGROUND

Despite effective antiretroviral therapy, cognitive impairment and other aging-related comorbidities are more prevalent in people with HIV (PWH) than in the general population. Previous research examining DNA methylation has shown PWH exhibit accelerated biological aging. However, it is unclear how accelerated biological aging may affect neural oscillatory activity in virally suppressed PWH, and more broadly how such aberrant neural activity may impact neuropsychological performance.

METHODS

In the present study, participants (n = 134) between the ages of 23 - 72 years underwent a neuropsychological assessment, a blood draw to determine biological age via DNA methylation, and a visuospatial processing task during magnetoencephalography (MEG). Our analyses focused on the relationship between biological age and oscillatory theta (4-8 Hz) and alpha (10 - 16 Hz) activity among PWH (n=65) and seronegative controls (n = 69).

RESULTS

PWH had significantly elevated biological age when controlling for chronological age relative to controls. Biological age was differentially associated with theta oscillations in the left posterior cingulate cortex (PCC) and with alpha oscillations in the right medial prefrontal cortex (mPFC) among PWH and seronegative controls. Stronger alpha oscillations in the mPFC were associated with lower CD4 nadir and lower current CD4 counts, suggesting such responses were compensatory. Participants who were on combination antiretroviral therapy for longer had weaker theta oscillations in the PCC.

CONCLUSIONS

These findings support the concept of interactions between biological aging and HIV status on the neural oscillatory dynamics serving visuospatial processing. Future work should elucidate the long-term trajectory and impact of accelerated aging on neural oscillatory dynamics in PWH.

Epigenetic aging as a biomarker of dementia and related outcomes: a systematic review

Background: Biological aging may be a robust biomarker of dementia or cognitive performance. This systematic review synthesized the evidence for an association between epigenetic aging and dementia, mild cognitive impairment and cognitive function. Methods: A systematic search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results: 30 eligible articles were included. There was no strong evidence that accelerated epigenetic aging was associated with dementia/mild cognitive impairment (n = 7). There was some evidence of an association with poorer cognition (n = 20), particularly with GrimAge acceleration, but this was inconsistent and varied across cognitive domains. A meta-analysis was not performed due to high study heterogeneity. Conclusion: There is insufficient evidence to indicate that current epigenetic aging clocks can be clinically useful biomarkers of dementia or cognitive aging.

Differential impact of movement on the alpha and gamma dynamics serving visual processing

Visual processing is widely understood to be served by a decrease in alpha activity in occipital cortices, largely concurrent with an increase in gamma activity. Although the characteristics of these oscillations are well documented in response to a range of complex visual stimuli, little is known about how these dynamics are impacted by concurrent motor responses, which is problematic as many common visual tasks involve such responses. Thus, in the current study, we used magnetoencephalography (MEG) and modified a well-established visual paradigm to explore the impact of motor responses on visual oscillatory activity. Thirty-four healthy adults viewed a moving gabor (grating) stimulus that was known to elicit robust alpha and gamma oscillations in occipital cortices. Frequency and power characteristics were assessed statistically for differences as a function of movement condition. Our results indicated that occipital alpha significantly increased in power during movement relative to no movement trials. No differences in peak frequency or power were found for gamma responses between the two movement conditions. These results provide valuable evidence of visuomotor integration and underscore the importance of careful task design and interpretation, especially in the context of complex visual processing, and suggest that even basic motor responses alter occipital visual oscillations in healthy adults.NEW & NOTEWORTHY Processing of visual stimuli is served by occipital alpha and gamma activity. Many studies have investigated the impact of visual stimuli on motor cortical responses, but few studies have systematically investigated the impact of motor responses on visual oscillations. We found that when participants are asked to move in response to a visual stimulus, occipital alpha power was modulated whereas gamma responses were unaffected. This suggests that these responses have dissociable roles in visuomotor integration.

Stress-induced aberrations in sensory processing predict worse cognitive outcomes in healthy aging adults

It is well recognized that not all individuals age equivalently, with functional dependence attributable, at least in part, to stress accumulated across the lifespan. Amongst these dependencies are age-related declines in cognitive function, which may be the result of impaired inhibitory processing (e.g., sensory gating). Herein, we examined the unique roles of life and biological stress on somatosensory gating dynamics in 74 adults (22-72 years old). Participants completed a sensory gating paired-pulse electrical stimulation paradigm of the right median nerve during magnetoencephalography (MEG) and data were subjected to advanced oscillatory and time-domain analysis methods. We observed separable mechanisms by which increasing levels of life and biological stress predicted higher oscillatory gating ratios, indicative of age-related impairments in inhibitory function. Specifically, elevations in life stress significantly modulated the neural response to the first stimulation in the pair, while elevations in biological stress significantly modulated the neural response to the second stimulation in the pair. In contrast, neither elevations in life nor biological stress significantly predicted the gating of time-domain neural activity in the somatosensory cortex. Finally, our study is the first to link stress-induced decline in sensory gating to cognitive dysfunction, suggesting that gating paradigms may hold promise for detecting discrepant functional trajectories in age-related pathologies in the future.

Posterior Alpha and Gamma Oscillations Index Divergent and Superadditive Effects of Cognitive Interference

Conflicts at various stages of cognition can cause interference effects on behavior. Two well-studied forms of cognitive interference are stimulus-stimulus (e.g., Flanker), where the conflict arises from incongruence between the task-relevant stimulus and simultaneously presented irrelevant stimulus information, and stimulus-response (e.g., Simon), where interference is the result of an incompatibility between the spatial location of the task-relevant stimulus and a prepotent motor mapping of the expected response. Despite substantial interest in the neural and behavioral underpinnings of cognitive interference, it remains uncertain how differing sources of cognitive conflict might interact, and the spectrally specific neural dynamics that index this phenomenon are poorly understood. Herein, we used an adapted version of the multisource interference task and magnetoencephalography to investigate the spectral, temporal, and spatial dynamics of conflict processing in healthy adults (N = 23). We found a double-dissociation such that, in isolation, stimulus-stimulus interference was indexed by alpha (8-14 Hz), but not gamma-frequency (64-76 Hz) oscillations in the lateral occipital regions, while stimulus-response interference was indexed by gamma oscillations in nearby cortices, but not by alpha oscillations. Surprisingly, we also observed a superadditive effect of simultaneously presented interference types (multisource) on task performance and gamma oscillations in superior parietal cortex.

Neural oscillations underlying selective attention follow sexually divergent developmental trajectories during adolescence

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A cohort of 9- to 16-year-olds completed a classic flanker task during MEG.

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There were developmentally-sensitive interference effects in key attention regions.

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Youth showed sexually-divergent patterns of age-related interference activity.

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Maturational differences among males supported improved task behavior.

Selective attention processes are critical to everyday functioning and are known to develop through at least young adulthood. Although numerous investigations have studied the maturation of attention systems in the brain, these studies have largely focused on the spatial configuration of these systems; there is a paucity of research on the neural oscillatory dynamics serving selective attention, particularly among youth. Herein, we examined the developmental trajectory of neural oscillatory activity serving selective attention in 53 typically developing youth age 9-to-16 years-old. Participants completed the classic arrow-based flanker task during magnetoencephalography, and the resulting data were imaged in the time-frequency domain. Flanker interference significantly modulated theta and alpha/beta oscillations within prefrontal, mid-cingulate, cuneus, and occipital regions. Interference-related neural activity also increased with age in the temporoparietal junction and the rostral anterior cingulate. Sex-specific effects indicated that females had greater theta interference activity in the anterior insula, whereas males showed differential effects in theta and alpha/beta oscillations across frontoparietal regions. Finally, males showed age-related changes in alpha/beta interference in the cuneus and middle frontal gyrus, which predicted improved behavioral performance. Taken together, these data suggest sexually-divergent developmental trajectories underlying selective attention in youth.

Altered fronto-occipital connectivity during visual selective attention in regular cannabis users

RATIONALE AND OBJECTIVES

Cognitive processing impairments have been associated with acute cannabis use, but there is mixed evidence regarding the cognitive effects of chronic cannabis use. Several neuroimaging studies have noted selective-attention processing differences in those who chronically use cannabis, but the neural dynamics governing the altered processing is unclear.

METHODS

Twenty-four adults reporting at least weekly cannabis use in the past 6 months on the Cannabis Use Disorder Identification Test - Revised were compared to 24 demographically matched controls who reported no prior cannabis use. All participants completed a visual selective attention processing task while undergoing magnetoencephalography. Time-frequency windows of interest were identified using a data-driven method, and spectrally specific neural activity was imaged using a beamforming approach.

RESULTS

All participants performed within normal range on the cognitive task. Regular cannabis users displayed an aberrant cognitive interference effect in the theta (4-8 Hz) frequency range shortly after stimulus onset (i.e., 0-250 ms) in the right occipital cortex. Cannabis users also exhibited altered functional connectivity between the right prefrontal cortex and right occipital cortices in comparison to controls.

CONCLUSIONS

Individuals with a history of regular cannabis use exhibited abnormal theta interference activity in the occipital cortices, as well as altered prefrontal-occipital functional connectivity in the theta range during a visual selective attention task. Such differences may reflect compensatory processing, as these participants performed within normal range on the task. Understanding the neural dynamics in chronic, regular cannabis users may provide insight on how long-term and/or frequent use may affect neural networks underlying cognitive processes.

Cortical oscillations that underlie visual selective attention are abnormal in adolescents with cerebral palsy

Adolescence is a critical period for the development and refinement of several higher-level cognitive functions, including visual selective attention. Clinically, it has been noted that adolescents with cerebral palsy (CP) may have deficits in selectively attending to objects within their visual field. This study aimed to evaluate the neural oscillatory activity in the ventral attention network while adolescents with CP performed a visual selective attention task. Adolescents with CP (N = 14; Age = 15.7 ± 4 years; MACS I-III; GMFCS I-IV) and neurotypical (NT) adolescents (N = 21; Age = 14.3 ± 2 years) performed the Eriksen flanker task while undergoing magnetoencephalographic (MEG) brain imaging. The participants reported the direction of a target arrow that was surrounded by congruent or incongruent flanking arrows. Compared with NT adolescents, adolescents with CP had slower responses and made more errors regarding the direction of the target arrow. The MEG results revealed that adolescents with CP had stronger alpha oscillations in the left insula when the flanking arrows were incongruent. Furthermore, participants that had more errors also tended to have stronger alpha oscillatory activity in this brain region. Altogether these results indicate that the aberrant activity seen in the left insula is associated with diminished visual selective attention function in adolescents with CP.

The aging transcriptome: read between the lines

The increasing sophistication of gene expression technologies has given rise to the idea that aging could be understood by analyzing transcriptomes. Mapping trajectories of gene expression changes in aging organisms, across different tissues and brain regions has provided insights on how biological functions change with age. However, recent publications suggest that transcriptional regulation itself deteriorates with age. Loss of transcriptional regulation will lead to non-regulated gene expression changes, but current analysis strategies were not designed to disentangle mixtures of regulated and non-regulated changes. Disentangling transcriptional data to distinguish adaptive, regulatory changes, from those that are the consequence of the age-associated deterioration is likely to create an analytical challenge but promises to unlock yet poorly understood aspects of many age-associated transcriptomes.