Dynamic modeling of practice effects across the healthy aging-Alzheimer’s disease continuum

Standardized tests of learning and memory are sensitive to changes associated with both aging and superimposed neurodegenerative diseases. Unfortunately, repeated behavioral test administration can be confounded by practice effects (PE), which may obscure declines in level of abilities and contribute to misdiagnoses. Growing evidence, however, suggests PE over successive longitudinal measurements may differentially predict cognitive status and risk for progressive decline associated with aging, mild cognitive impairment (MCI), and dementia. Thus, when viewed as a reflection of neurocognitive plasticity, PE may reveal residual abilities that can add to our understanding of age- and disease-related changes in learning and memory. The present study sought to evaluate differences in PE and verbal recall in a clinically characterized aging cohort assessed on multiple occasions over 3 years. Participants included 256 older adults recently diagnosed as cognitively unimpaired (CU; n = 126), or with MCI of amnestic (n = 65) or non-amnestic MCI (n = 2085), and multi-domain amnestic dementia of the Alzheimer’s type (DAT; n = 45). We applied a continuous time structural equation modeling (ctsem) approach to verbal recall performance on the Hopkins Verbal Learning Test in order to distinguish PE from individual occasion performance, coupled random changes, age trends, and differing measurement quality. Diagnoses of MCI and dementia were associated with lower recall performance on all trials, reduced PE gain per occasion, and differences in non-linear dynamic parameters. Practice self-feedback is a dynamic measure of the decay or acceleration in PE process changes over longitudinal occasions. As with PE and mean recall, estimated practice self-feedback followed a gradient from positive in CU participants to null in participants with diagnosed MCI and negative for those with dementia diagnoses. Evaluation of sensitivity models showed this pattern of variation in PE was largely unmodified by differences in age, sex, or educational attainment. These results show dynamic modeling of PE from longitudinal performance on standardized learning and memory tests can capture multiple aspects of behavioral changes in MCI and dementia. The present study provides a new perspective for modeling longitudinal change in verbal learning in clinical and cognitive aging research.

Toward rational use of cognitive training in those with mild cognitive impairment

The term cognitive training includes a range of techniques that hold potential for treating cognitive impairment caused by neurologic injury and disease. Our central premise is that these techniques differ in their mechanisms of action and therefore engage distinct brain regions (or neural networks). We support this premise using data from a single-blind randomized-controlled trial in which patients with mild cognitive impairment were randomized to either mnemonic strategy training (MST) or spaced retrieval training (SRT) as they learned ecologically relevant object-location associations. Both training approaches were highly effective in the short term, but MST demonstrated a clear advantage after days to weeks. MST also increased activation in and functional connectivity between frontal, temporal, and parietal regions as well as the hippocampus. In contrast, patterns of reduced activation and functional connectivity were evident following SRT. These findings support the rational development of cognitive training techniques.

Efficacy and safety of HD-tDCS and respiratory rehabilitation for critically ill patients with COVID-19 The HD-RECOVERY randomized clinical trial

Background and purpose

Acute Respiratory Distress Syndrome (ADRS) due to coronavirus disease 2019 (COVID-19) has been associated with muscle fatigue, corticospinal pathways dysfunction, and mortality. High-Definition transcranial Direct Current Stimulation (HD-tDCS) may be used to attenuate clinical impairment in these patients. The HD-RECOVERY randomized clinical trial was conducted to evaluate the efficacy and safety of HD-tDCS with respiratory rehabilitation in patients with moderate to severe ARDS due to COVID-19.

Methods

Fifty-six critically ill patients were randomized 1:1 to active (n = 28) or sham (n = 28) HD-tDCS (twice a day, 30-min, 3-mA) plus respiratory rehabilitation for up to 10 days or until intensive care unit discharge. The primary outcome was ventilator-free days during the first 28 days, defined as the number of days free from mechanical ventilation. Furthermore, secondary outcomes such as delirium, organ failure, hospital length of stay and adverse effects were investigated.

Results

Active HD-tDCS induced more ventilator-free days compared to sham HD-tDCS. Patients in the active group vs in the sham group experienced lower organ dysfunction, delirium, and length of stay rates over time. In addition, positive clinical response was higher in the active vs sham group. There was no significant difference in the prespecified secondary outcomes at 5 days. Adverse events were similar between groups.

Conclusions

Among patients with COVID-19 and moderate to severe ARDS, use of active HD-tDCS compared with sham HD-tDCS plus respiratory rehabilitation resulted in a statistically significant increase in the number of ventilator-free days over 28 days. HD-tDCS combined with concurrent rehabilitation therapy is a safe, feasible, potentially add-on intervention, and further trials should examine HD-tDCS efficacy in a larger sample of patients with COVID-19 and severe hypoxemia.

Validation of the National Alzheimer's Coordinating Center (NACC) Lewy Body Disease Module neuropsychological tests

INTRODUCTION

This study assessed the construct validity and clinical utility of the National Alzheimer's Coordinating Center Lewy Body Dementia (LBD) Module, consisting of the Speeded Attention and Noise Pareidolia Tasks.

METHODS

Participants included 459 older adults diagnosed as cognitively normal (n = 202), or with non-amnestic mild cognitive impairment (n = 61), amnestic mild cognitive impairment (n = 96), Alzheimer's disease dementia (n = 44), or LBD (n = 56).

RESULTS

Speeded Attention demonstrated strong convergent validity and moderate discriminant validity when compared to established neuropsychological tests. Noise Pareidolia demonstrated strong discriminant validity, but limited convergent validity. Noise Pareidolia scores were significantly lower in those with reported hallucinations, delusions, or REM sleep behavior disorder symptoms. LBD Module tests discriminated well between cognitively normal adults and those with LBD.

DISCUSSION

The LBD Module demonstrates promising construct validity and clinical utility, which support its use across research and clinical settings.

High-definition transcranial direct current stimulation enhances network segregation during spatial navigation in mild cognitive impairment

Spatial navigation is essential for everyday life and relies on complex network-level interactions. Recent evidence suggests that transcranial direct current stimulation (tDCS) can influence the activity of large-scale functional brain networks. We characterized brain-wide changes in functional network segregation (i.e. the balance of within vs. between-network connectivity strength) induced by high-definition (HD) tDCS in older adults with mild cognitive impairment (MCI) during virtual spatial navigation. Twenty patients with MCI and 22 cognitively intact older adults (healthy controls-HC) underwent functional magnetic resonance imaging following two counterbalanced HD-tDCS sessions (one active, one sham) that targeted the right parietal cortex (center anode at P2) and delivered 2 mA for 20 min. Compared to HC, MCI patients showed lower brain-wide network segregation following sham HD-tDCS. However, following active HD-tDCS, MCI patients' network segregation increased to levels similar to those in HC, suggesting functional normalization. Follow-up analyses indicated that the increase in network segregation for MCI patients was driven by HD-tDCS effects on the "high-level"/association brain networks, in particular the dorsal-attention and default-mode networks. HD-tDCS over the right parietal cortex may normalize the segregation/integration balance of association networks during spatial navigation in MCI patients, highlighting its potential to restore brain activity in Alzheimer's disease.

Effects of High Definition-Transcranial Direct Current Stimulation on Local GABA and Glutamate Levels Among Older Adults with and without Mild Cognitive Impairment: An Exploratory Study

BACKGROUND

Prior research, primarily with young adults, suggests transcranial direct current stimulation (tDCS) effects are driven by the primary excitatory and/or inhibitory neurotransmitters, glutamate, and gamma-aminobutyric acid (GABA), respectively.

OBJECTIVE

We examined the neurometabolic mechanisms of tDCS in older adults with and without mild cognitive impairment (MCI).

METHODS

We used data from a double-blind, cross-over, randomized controlled trial (NCT01958437) in 32 older adults to evaluate high definition (HD)-tDCS-induced changes in glutamate and GABA via magnetic resonance spectroscopy (MRS). Participants underwent MRS following two counterbalanced HD-tDCS sessions (one active, one sham) that targeted the right superior parietal cortex (center anode at P2) and delivered 2mA for 20 minutes.

RESULTS

Relative to sham, and when co-varying for MRS voxel overlap and right superior parietal volume, active HD-tDCS significantly increased GABA and decreased the ratio of glutamate to GABA. No changes were observed in a left prefrontal control MRS voxel. Although we did not find a significant correlation between strength of delivered current (measured via MRI-based computational modeling) and neurometabolite change, there was a robust positive relationship between the volume of right superior parietal cortex and neurometabolite change.

CONCLUSION

Our preliminary findings of increased GABA and reduced glutamate/GABA ratio raise the possibility that (HD-)tDCS effects differ by age. Moreover, age- and disease-related regional brain volume loss may be especially important to consider when planning future studies. Replication would emphasize the importance of developing population-specific tDCS parameters that consider structural and physiologic changes associated with "normal" and pathological aging.

Psychometric evaluation of the Hopkins Rehabilitation Engagement Rating Scale in postacute physical therapy services

PURPOSE/OBJECTIVE

Evaluate the reliability and validity of the Hopkins Rehabilitation Engagement Scale (HRERS) in a postacute rehabilitation sample. We hypothesized that HRERS items would comprise a single factor, and would demonstrate adequate internal consistency and temporal stability, and significant relationships with key constructs. Research Method and Design: Retrospective medical record review between 2016 and 2017 of older veterans (N = 107) admitted to a community living center postacute care (CLC-PAC) rehabilitation hospital unit to address targeted physical therapy rehabilitation goals. Inclusion criteria included availability of two HRERS administrations at Time 1 (admission) and Time 2 (approximately one-month follow-up or physical therapist/CLC-PAC discharge).

RESULTS

Across timepoints, HRERS items reflect a single factor of engagement, and the scale has good internal consistency at admission (Time 1, α = .759) and follow-up (Time 2, α = .877). The temporal stability of HRERS across ratings was r = .56 (p < .001). Increased pain rating (r = -.309, p < .01) and depressive symptoms (-.287, p < .01) at admission correlates with subsequent physical therapist (PT) engagement (HRERS Time 2). Low admission PT engagement correlates with less frequent PT attendance (r = -.242, p < .01) and greater number of consults placed during the CLC stay (r = -.222, p < .05).

CONCLUSIONS/IMPLICATIONS

HRERS is a reliable and valid measure of PT engagement in older CLC-PAC Veterans. Findings support the administration of the HRERS at more than one timepoint during rehabilitation to inform interventions targeting select behavioral health factors such as pain and depression. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The Internet-Based Conversational Engagement Clinical Trial (I-CONECT) in Socially Isolated Adults 75+ Years Old: Randomized Controlled Trial Protocol and COVID-19 Related Study Modifications

Background: Increasing social interactions through communication technologies could offer a cost-effective prevention approach that slows cognitive decline and delays the onset of Alzheimer's disease. This paper describes the protocol of an active project named "Internet-based conversational engagement clinical trial (I-CONECT)" (ClinicalTrials.gov: NCT02871921). The COVID-19 pandemic related protocol modifications are also addressed in the current paper. Methods: I-CONECT is a multi-site, assessor-blind, randomized controlled behavioral intervention trial (RCT). We aim to randomize 320 socially isolated adults 75+ years old [160 Caucasian and 160 African American participants, 50:50 split between those with normal cognition and mild cognitive impairment (MCI)] recruited from the community to either the video chat intervention group or the control group (1:1 allocation). Those in the video chat group receive a computer and Internet service for the duration of the study, which they use to video chat with study staff for 30 min/day 4×/week for 6 months (high dose), and then 2×/week for an additional 6 months (maintenance dose). Both video chat and control groups have a brief (about 10 min) telephone check-in with study staff once per week. The primary outcome is the change in global cognitive function measured by Montreal Cognitive Assessment (MoCA) from baseline to 6 months. Secondary outcomes include changes in cognition in memory and executive function domains, emotional well-being measured by NIH Toolbox emotional battery, and daily functional abilities assessed with the Revised Observed Tasks of Daily Living (OTDL-R). Eligible participants have MRIs at baseline and 6 months. Participants contribute saliva for genetic testing (optional consent), and all video chats, weekly check-in calls and neuropsychological assessment sessions are recorded for speech and language analysis. The pandemic halted research activities and resulted in protocol modifications, including replacing in-person assessment with remote assessment, remote deployment of study equipment, and revised targeted sample size. Discussion: This trial provides user-friendly hardware for the conversational-based intervention that can be easily provided at participants' homes. The trial aspires to use age and culture-specific conversational materials and a related platform developed in this trial for enhancing cognitive reserve and improving cognitive function.

CogTale: an online platform for the evaluation, synthesis, and dissemination of evidence from cognitive interventions studies

Systematic reviews and meta-analyses are critical in health-related decision-making, and are considered the gold standard in research synthesis methods. However, with new trials being regularly published and with the development of increasingly rigorous standards of data synthesis, systematic reviews often require much expertise and long periods of time to be completed. Automation of some of the steps of evidence synthesis productions is a promising improvement in the field, capable of reducing the time and costs associated with the process.This article describes the development and main characteristics of a novel online repository of cognitive intervention studies entitled Cognitive Treatments Article Library and Evaluation (CogTale). The platform is currently in a Beta Release phase, as it is still under development. However, it already contains over 70 studies, and the CogTale team is continuously coding and uploading new studies into the repository. Key features include advanced search options, the capability to generate meta-analyses, and an up-to-date display of relevant published studies.

Cognitive screening assessment in Thai older adults: a prospective study of the reliability and validity of the Abbreviated Mental Test

Purpose –

The purpose of this paper is to examine the reliability and validity of the Abbreviated Mental Test (AMT) and the agreement with the Mini-Mental State Examination (MMSE).

Design/methodology/approach –

This cross-sectional study included 446 older adults who were recruited by cluster sampling from 200,481 adults aged more than 60 years. For each participant, the AMT was administered by village health volunteers and, on a separate day, by a trained professional who also administered the MMSE. Descriptive statistics, Bland and Altman levels of agreement, and Receiver Operator Curves (ROCs) were used to analyze data.

Findings –

Administration of the AMT by village health volunteers during the annual health screening found cognitive impairment in only 1.12% of the sample. When the AMT was given to these same individuals by trained professionals, the rate of cognitive impairment was almost 24 times greater. Two items in the Thai AMT may require modification due to markedly elevated failure rates. At the cut score of 8, the sensitivity and specificity of the AMT relative to the MMSE were moderate (78.83 and 66.67%, respectively). The degree of agreement between AMT and MMSE was 0.49 (p < 0.001) and the correlation between the difference scores and the mean is exceptionally low (0.048).

Originality/value –

Reliable and valid cognitive screening assessment requires the administrator to be well trained and the tools to be appropriate for the population. Although AMT is short and easy for a nonprofessional to administer, some items were not suitable due to construct validity and contextual issues.

Toward a theory-based specification of non-pharmacological treatments in aging and dementia: Focused reviews and methodological recommendations

INTRODUCTION

Non-pharmacological treatments (NPTs) have the potential to improve meaningful outcomes for older people at risk of, or living with dementia, but research often lacks methodological rigor and continues to produce mixed results.

METHODS

In the current position paper, experts in NPT research have specified treatment targets, aims, and ingredients using an umbrella framework, the Rehabilitation Treatment Specification System.

RESULTS

Experts provided a snapshot and an authoritative summary of the evidence for different NPTs based on the best synthesis efforts, identified main gaps in knowledge and relevant barriers, and provided directions for future research. Experts in trial methodology provide best practice principles and recommendations for those working in this area, underscoring the importance of prespecified protocols.

DISCUSSION

We conclude that the evidence strongly supports various NPTs in relation to their primary targets, and discuss opportunities and challenges associated with a unifying theoretical framework to guide future efforts in this area.

Does the Abbreviated Mental Test Accurately Predict Cognitive Impairment in Thai Older Adults? A Retrospective Study

The Abbreviated Mental Test is a screening tool for cognitive impairment in older adults now used in Thailand's annual national cognitive assessment required for all community-dwelling older adults in Thailand, however its validity has not been established for this purpose. This retrospective study evaluated the results of this abbreviated test as well as the Mini Mental State Examination, in a sample of older adults who participated in the national cognitive assessment in 2018 in Udon Thani Province, Thailand. Of the 174,227 cases, 1518 cases had scores on both tests. The Mini-Mental State Examination is performed on a select group of individuals who scored low on the initial and briefer test. Results indicated that the proportion of cognitive impairment as defined by the Abbreviated Mental Test (87.7%) was five times higher than indicated by the more rigorous Mini-Mental State Examination (16.3%). At the AMT standard cut point of 8 out of a total possible score of 10 for the presence of cognitive impairment, sensitivity was low (12.8%) but specificity was high (90.3%), while the optimal cut-point of 5 on the Receiver Operating Characteristic Curve errs on the side of being highly sensitive but not specific enough to screen for cognitive impairment. Additionally, one item on the AMT was answered incorrectly by 95% of responders. Although brief and easy to administer, the AMT may be a suboptimal choice for screening for cognitive impairment. When administered by volunteer health workers, the AMT may also possess limited reliability and validity. Cognitive screening administered by nurses should be considered to help detect cognitive impairment older adults dwelling in the community.

HD-tDCS as a neurorehabilitation technique for a case of post-anoxic leukoencephalopathy

Post-anoxic leukoencephalopathy is a rare event that causes global demyelination secondary to anoxic injury. Given the nature and extent of the damage, cognitive and functional deficits are typically chronic even after standard therapies. Here, we describe a novel treatment approach that used high definition transcranial direct-current stimulation (HD-tDCS) with a 62-year-old male who was 5 years post-anoxic leukoencephalopathy secondary to an accidental drug overdose. HD-tDCS was administered over the left lateral prefrontal cortex across 29 daily sessions at 2 mA (20 min/session) in order to address dysexecutive behaviors. Results demonstrated improved delayed memory and trends for improved visuospatial and semantic fluency performance as well as improved insight and daily functioning, all of which returned to baseline by the end of a 10 week no-contact follow up period. Resting state fMRI connectivity results mirrored these changes by showing increased dorsal attention and cingulo-opercular but reduced ventral attention network connectivity after session 29, all of which returned to baseline at follow-up. These findings suggest HD-tDCS may benefit functioning even following serious and pervasive anoxic injury. Findings also suggest the need for continued HD-tDCS for maintenance purposes, though future work is needed to identify optimal dose-response information.

EA, Busatto GF, Bottino CMC. Mnemonic strategy training modulates functional connectivity at rest in mild cognitive impairment: Results from a randomized controlled trial

INTRODUCTION

Mnemonic strategy training (MST) has been shown to improve cognitive performance and increase brain activation in those with mild cognitive impairment (MCI). However, little is known regarding the effects of MST on functional connectivity (FC) at rest. The aim of the present study was to investigate the MST focused on face-name associations effect on resting-state FC in those with MCI.

METHODS

Twenty-six amnestic MCI participants were randomized in MST (N = 14) and Education Program (active control; N = 12). Interventions occurred twice a week over two consecutive weeks (ie, four sessions). Resting-state functional magnetic resonance imaging was collected at pre- and post-intervention. Regions of interest (ROIs) were selected based on areas that previously showed task-related activation changes after MST. Changes were examined through ROI-to-ROI analysis and significant results were corrected for multiple comparisons.

RESULTS

At post-intervention, only the MST group showed increased FC, whereas the control group showed decreased or no change in FC. After MST, there was an increased FC between the left middle temporal gyrus and right orbitofrontal cortex. In addition, a time-by-group interaction indicated that the MST group showed greater increased FC between the right inferior frontal gyrus and left brain regions, such as fusiform gyrus, temporal pole, and orbitofrontal cortex relative to controls.

DISCUSSION

MST enhanced FC in regions that are functionally relevant for the training; however, not in all ROIs investigated. Our findings suggest that MST-induced changes are reflected in task-specific conditions, as previously reported, but also in general innate connectivity. Our results both enhance knowledge about the mechanisms underlying MST effects and may provide neurophysiological evidence of training transfer.

The design, evaluation, and reporting on non-pharmacological, cognition-oriented treatments for older adults: Results of a survey of experts

Introduction

Cognitive decline and dementia significantly affect independence and quality of life in older adults; therefore, it is critical to identify effective cognition-oriented treatments (COTs; eg, cognitive training, rehabilitation) that can help maintain or enhance cognitive functioning in older adults, as well as reduce dementia risk or alleviate symptoms associated with pathological processes.

Methods

The Cognitive Intervention Design Evaluation and Reporting (CIDER), a working group from the Non-Pharmacological Interventions Professional Interest Area (NPI-PIA) of the Alzheimer's Association conducted as survey in 2017 with experts in COTs worldwide. The survey's aims were three-fold: (1) determine the common attitudes, beliefs, and practices of experts involved in the COTs research targeting older people; (2) identify areas of relative agreement and disagreement among experts in the field; and (3) offer a critical review of the literature, including recommendations for future research.

Results

The survey identified several areas of agreements among experts on critical features of COTs, and on study design and outcome measures. Nevertheless, there were some areas with relative disagreement. Critically, expert opinions were not always supported by scientific evidence, suggesting that methodologic improvements are needed regarding design, implementation, and reporting of COTs. There was a clear consensus that COTs provide benefits and should be offered to cognitively unimpaired older adults, mild cognitive impairment (MCI), and mild dementia, but opinions differed for moderate and severe dementia. In addition, there is no consensus on the potential role of COTs in dementia prevention, indicating that future research should prioritize this aspect.

Discussion

Evidence of COTs in older adults is encouraging, but additional evidence is needed to enhance dementia prevention. Consensus building and guidelines in the field are critical to improve and accelerate the development of high-quality evidence for COTs in cognitively unimpaired older adults, and those with MCI and dementia.

The effects of strategy training on spatial memory in diencephalic amnesia: a randomized controlled study

Alcoholic Korsakoff’s syndrome is characterized by severe amnesia, also affecting spatial memory. To date, research on cognitive rehabilitation in these patients is scarce. Aim of the present study is to examine the efficacy of a mnemonic strategy training in patients with Korsakoff’s syndrome. A randomized controlled exploratory study was performed. A convenience sample of 14 patients with amnesia due to alcoholic Korsakoff’s syndrome was included and randomized into a mnemonic strategy training group (n = 7) and a control group (n = 7). The training group completed a 3-day 45–60 min mnemonic strategy training that focused on specific strategies to encode and retrieve information about specific objects and their locations in virtual rooms, using labeling, verbal reasoning and mental imagery. The control group only received care as usual. Outcome measure was an object-location memory task consisting of novel, untrained object locations administered 1 day before the intervention, as well as 1 day and 1 week after completing the intervention. Patients in the intervention group were able to acquire and use the strategies, but no significant differences were found between the intervention group and the control group, and no significant change in performance was demonstrated compared to baseline 1 day and 1 week after the intervention. To conclude, the mnemonic strategy training in KS patients did not result in a better spatial memory performance 1 day or 1 week after training completion compared to participation in the regular non-cognitive treatment program that focused on occupational therapy, music therapy and exercise.

Model-based assessment and neural correlates of spatial memory deficits in mild cognitive impairment

Mild cognitive impairment (MCI) is characterized by subjective and objective memory impairments within the context of generally intact everyday functioning. Such memory deficits are typically thought to arise from medial temporal lobe dysfunction; however, differences in memory task performance can arise from a variety of altered processes (e.g., strategy adjustments) rather than, or in addition to, "pure" memory deficits. To address this problem, we applied the linear ballistic accumulator (LBA: Brown and Heathcote, 2008) model to data from individuals with MCI (n = 18) and healthy older adults (HOA; n = 16) who performed an object-location association memory retrieval task during functional magnetic resonance imaging (fMRI). The primary goals were to 1) assess between-group differences in model parameters indexing processes of interest (memory sensitivity, accumulation speed, caution and time spent on peripheral perceptual and motor processes) and 2) determine whether differences in model-based metrics were consistent with fMRI data. The LBA provided evidence that, relative to the HOA group, those with MCI displayed lower sensitivity (i.e., difficulty discriminating targets from lures), suggestive of memory impairment, and displayed higher evidence accumulation speed and greater caution, suggestive of increased arousal and strategic changes in this group, although these changes had little impact on MCI-related accuracy differences. Consistent with these findings, fMRI revealed reduced activation in brain regions previously linked to evidence accumulation and to the implementation of caution reductions in the MCI group. Findings suggest that multiple cognitive mechanisms differ during memory retrieval in MCI, and that these mechanisms may explain neuroimaging alterations outside of the medial temporal lobes.

Variable symptomatic and neurophysiologic response to HD-tDCS in a case series with posttraumatic stress disorder

Chronic Posttraumatic stress disorder (PTSD), characterized by symptoms of re-experiencing, hyperarousal, and avoidance, is challenging to treat as a significant proportion of patients remain symptomatic following even empirically supported interventions. The current case series investigated the effects of up to 10 sessions of high definition transcranial direct current stimulation (HD-tDCS) on symptoms of PTSD. Participants received HD-tDCS that targeted the right lateral temporal cortex (LTC; center cathode placed over T8), given this region's potential involvement in symptoms of re-experiencing and, possibly, hyperarousal. Five of the six enrolled patients completed at least 8 sessions. Of these five, four showed improvement in symptoms of re-experiencing after HD-tDCS. This improvement was accompanied by connectivity change in the right LTC as well as a larger extended fear network but not a control network that consisted of visual cortex regions; however, the nature of the change varied across participants as some showed increased connectivity whereas others showed decreased connectivity. These preliminary data suggest that HD-tDCS may be beneficial for treatment of specific PTSD symptoms, in at least some individuals, and warrants further investigation.

TASK-SPECIFIC METACOGNITIVE ACCURACY DECLINES ACROSS THE DEMENTIA-ALZHEIMER’S TYPE SPECTRUM

Subjective cognitive complaints (SCCs) remain part of the diagnostic criteria for amnestic mild cognitive impairment (aMCI), the prodromal stage of dementia - Alzheimer’s type (DAT), despite weak relationships between self-reported and objectively-measured functioning. Most metacognitive measures focus on ratings of global retrospective memory rating only; greater subtlety in measurement of SCCs is required. Similarly, it is critical to identify the disease stage at which the clinical utility of SCCs is nullified by impaired insight. This study aims to evaluate group differences in (a) task-specific metacognitive ratings, and (b) the accuracy of these ratings in individuals diagnosed as cognitively intact (CI), with aMCI, or with DAT. 99 older adults (M-age = 69.43, SD-age = 6.98; M-edu = 15.54, SD-edu = 2.47; CI: n = 50, aMCI: n = 34, DAT: n = 15) enrolled in the University of Michigan Memory and Aging Project rated their performance on the Object Location Touchscreen Task (OLTT), an ecologically valid memory measure. One-way analysis of variance (ANOVA) revealed that individuals with aMCI-multiple domain or DAT rated their memory performance similarly to CI individuals, though the aMCI-single domain group rated themselves as more impaired. Bivariate Pearson’s r correlations demonstrated a decline in the strength of the relationship between task-specific metacognitive ratings and actual OLTT memory performance with increasing diagnostic severity. These findings suggest a decline in insight on task-specific memory ratings across the DAT spectrum, and call into question the use of self-reported SCCs as a diagnostic tool in later stages of disease progression.