Arijit K. Bhaumik

Can anchor models explain inverted-U effects in facial judgments?

Researchers in a variety of disciplines have found that participants take less time and generate less diversity of responses when judging stimuli towards the ends of a scale than when judging those near the center. Three types of models, connectionist, exemplar, and anchor models, can account for these inverted-U effects. Anchor models assume that stimuli near the ends of the scale are used as anchors to compare with the other stimuli, implying that anchor representations are activated for each judgment. Therefore, participants should learn the anchors better than the other stimuli. Participants were 40 students from the Department of Psychology at McGill University (5 men; M age = 20.5 yr.; SD = 1.7). The experiment involved two tasks: first participants judged facial gender and then performed a recognition task. The results showed no correlation between the position on the gender scale and recognition accuracy. Several hypotheses were offered to explain these results.

Translational MRI Volumetry with NeuroQuant: Effects of Version and Normative Data on Relationships with Memory Performance in Healthy Older Adults and Patients with Mild Cognitive Impairment

NeuroQuant (NQ) is a fully-automated program that overcomes several existing limitations in the clinical translation of MRI-derived volumetry. The current study characterized differences between the original (NQ1) and an updated NQ version (NQ2) by 1) replicating previously identified relationships between neuropsychological test performance and medial temporal lobe volumes, 2) evaluating the level of agreement between NQ versions, and 3) determining if the addition of NQ2 age-/sex-based z-scores hold greater clinical utility for prediction of memory impairment than standard percent of intracranial volume (% ICV) values. Sixty-seven healthy older adults and 65 mild cognitive impairment patients underwent structural MRI and completed cognitive testing, including the Immediate and Delayed Memory indices from the Repeatable Battery for the Assessment of Neuropsychological Status. Results generally replicated previous relationships between key medial temporal lobe regions and memory test performance, though comparison of NQ regions revealed statistically different values that were biased toward one version or the other depending on the region. NQ2 hippocampal z-scores explained additional variance in memory performance relative to % ICV values. Findings indicate that NQ1/2 medial temporal lobe volumes, especially age- and sex-based z-scores, hold clinical value, though caution is warranted when directly comparing volumes across NQ versions.

TASK-RELATED FMRI CHANGE AFTER HIGH-DEFINITION TRANSCRANIAL DIRECT CURRENT STIMULATION IN COGNITIVELY INTACT OLDER ADULTS AND PATIENTS WITH MCI

diabetes, cardiovascular and cerebrovascular disease, brain atrophy, and total gray matter where appropriate. We focused on executive functions as meta-analyses suggest that aerobic exercise has larger benefits for this cognitive domain. Results:In the PROMoTE RCT, we found that compared to usual care control, AT significantly improved executive functioning in females, but not males, an effect that was still evident 6 months later (p’s<0.05). Further, AT increased levels of brain derived neurotrophic factor in females compared to males (p<0.01). In the Health ABC data, higher initial PA and increased PA over time were associated with less decline in executive functioning over time in females (p’s<0.05), but not males (see Figure 1). Interestingly, maintenance of PA over time was related to larger left dorsal lateral prefrontal cortical volume in females only (p<0.05). Conclusions: Together, these findings provide evidence that sex differences exist in the effect of PA on cognition as well as in the underlying neurobiological mechanisms. This new knowledge can foster development of efficacious and sexspecific exercise recommendations to promote brain health.

DIAGNOSTIC UTILITY OF NIH TOOLBOX COGNITION BATTERY IN OLDER ADULTS WITH AMNESTIC MILD COGNITIVE IMPAIRMENT

CogState Brief Battery and the Auditory Verbal Learning Test (AVLT). Using the ATN (amyloid, tau, and neurodegeneration/ neuronal injury) framework, we focused on a subset of biomarker positive individuals we hypothesized are most likely to demonstrate subtle cognitive dysfunction. Biomarker positive subjects (n 1⁄4 29, A+T+Nor A+T+N+; median age 1⁄4 79.5, range 65-87; percent male 1⁄4 65.5) were older than biomarker negative subjects (n 1⁄4 47 A-T-N-; median age 1⁄4 61.3, range 1⁄4 50-83; percent male 1⁄4 44.7); groups did not significantly differ on gender or education. Subtle cognitive dysfunction was defined as performance -1SD on the CogState Learning/Working Memory Composite using age-corrected normative data provided by CogState and age-corrected published normative scores for AVLT 30-minute delayed recall (Ivnik et al., 1992 TCN). Results:Biomarker positive subjects showed a higher frequency of subtle cognitive dysfunction (15.4%) relative to biomarker negative subjects (2.2%) on the CogState Learning/WorkingMemory Composite (c1⁄4 4.49, p1⁄4 .05), particularly on One Card Learning accuracy that contributes to this composite score (c 1⁄4 5.27, p 1⁄4 .02; biomarker positive 23.1%, biomarker negative 4.3%). The frequency of subtle cognitive dysfunction on the AVLT 30-minute delayed recall was comparable across groups (p> .99; biomarker positive 19.2%, biomarker negative 17.0%). Conclusions:Cognitively unimpaired biomarker positive participants showed a higher frequency of subtle cognitive dysfunction on select CogState measures relative to biomarker negative subjects, although the frequency of subtle cognitive dysfunction was low. Further investigation of subtle cognitive dysfunction in preclinical Alzheimer’s disease may be useful for predicting biomarker status among CU adults.

PREDICTORS OF CHANGE ON NIH TOOLBOX-COGNITION AND COGSTATE BRIEF BATTERY IN A SAMPLE OF AFRICAN-AMERICAN SENIORS WITH COGNITIVE COMPLAINTS

began to experience impairment in memory and activities of daily living. The cognitive domains were examined using MMSE and MoCA, which showed that the patient had impaired performance in domains related to attention, orientation to time and memory. The attentional system was measured by Attention Network Task – Revised (ANT-R) comprises of three attentional networks that are alerting which prepares for fast response bymaintaining an alert state, orienting network which selectively allocates attention to a relevant area of the visual field and executive control which involves planning, making decision, detecting errors and dealing conflict. Results: The attentional network scores were calculated and patient score on alerting network was found to be lowest in comparison to orienting and executive control network. Conclusions:Overall result showed that the executive control network is inhibited by the alerting network, whereas the orienting network improves the efficiency of the executive control network.

HIGH-DEFINITION TRANSCRANIAL DIRECT CURRENT STIMULATION MODULATES BOLD SIGNAL DURING SPATIAL NAVIGATION IN OLDER CONTROLS AND PATIENTS WITH MCI

Background:Apathy is the most common neuropsychiatric symptom in Alzheimer’s disease (AD), occurs early in the disease process, and is associated with poor cognitive and functional outcomes. The neurobiological underpinnings for the expression of apathy in AD are not clearly understood and can be assessed via neuroimaging techniques to reveal key mechanisms and treatment targets. Methods: 1. Apathy was assessed in 87 individuals with mild to moderate AD, using the SANS-AD to measure each of the specific cognitive, functional, and emotional domains of apathy. FDG-PET neuroimaging was used to assess the pattern of hypometabolism associated with each apathy domain. 2. Global and individual domains of apathy were measured in 29 individuals with AD. 2FA neuroimaging was used to measure regional a4b2 nicotinic cholinergic receptor binding and to assess relationships between cholinergic receptor binding and the extent of global and domain-specific apathy. 3. A literature review of neuroimaging studies of apathy in AD was performed. Results: Structural and functional imaging studies using MRI, FDG-PET, or perfusion SPECT typically revealed alterations in anterior cingulate, orbitofrontal cortex, and insula associated with apathy in AD. Other frontal regions, temporal cortex, or subcortical nuclei were implicated in some studies, and there was overlap with regions linked to poor insight. Frontal white matter lesions and loss of integrity of white matter tracts on DTI images were also relevant. Associations in MCI were less clear. Apathy was associated with increased global or regional amyloid ligand binding. Each of the three apathy domains was associated with hypometabolism in a unique set of brain regions in AD. Greater apathy was correlated with lower cholinergic binding in middle cingulate and lateral orbitofrontal cortex. Across the neuroimaging studies, relationships were not attributable to depression. Conclusions: Neuroimaging studies indicate that altered structure, function, or neuroreceptor binding in a frontal-limbic-subcortical neural system are associated with apathy in AD. Specific regional alterations drive distinct aspects of apathy and neurotransmitter levels may influence overall tone. Disease-related alterations across this neural system likely promote dysfunction in directed attention, stimulus salience assessment, emotional processing, affective drive, and reward-related decision-making that emerge as clinical apathy in AD.

NIH TOOLBOX-COGNITIVE AND COGSTATE COMPUTER-BASED ASSESSMENT IN THE IDENTIFICATION OF MCI SUBTYPES

nucleus (Figure 1). Conclusions: CBF decreased as individuals approached the expected age of disease onset and this CBF decrease was accelerated in the presymptomatic mutation carriers compared to controls, in key regions implicated in FTD. These preliminary findings demonstrate the potential utility of non-invasive perfusion MRI as an early biomarker for genetic FTD. References 1. Montine et al., Neurology 2014 2. Rohrer et al., Lancet Neurol 2015

COGSTATE AND NIH TOOLBOX-COGNITIVE COMPUTERIZED TEST BATTERIES: REPEAT ASSESSMENTS AMONG AFRICAN-AMERICAN ELDERS

Background:Unsupervised web-based cognitive assessment could widen and refine recruitment into clinical trials while reducing costs. However, challenges to reliability exist which are not present in supervised testing. We were interested in establishing: 1) the comparability of web-based testing to supervised testing 2) The development of measures related to participant compliance and engagement. Methods: Six hundred participants between 18 and 70 were recruited for online testing, and were matched to 94 participants assessed in a supervised setting on age and gender. Participants completed an adaptive test of episodic memory (Paired Associates Learning PAL) from Cantab. Demographic and background data (e.g. age, education) were also recorded. Participants in the supervised testing were assessed on iPads, whereas in online testing participants used a variety of systems, including desktop computers, laptops and tablet devices. Results:There was no difference in PAL errors between supervised and web-based testing. Within the web-based testing, there was no difference between hardware platforms or browser. However, trial-by-trial timing data showed highly variable and slow reaction times in a number of participants during web-based testing, outside the bounds seen on supervised testing. This was associated with more PAL errors (r1⁄4.35), and younger age (r1⁄4.-21). Test-retest reliability was increased when participants with speed and variability parameters outside those of supervised testing were excluded.Web browser activity monitoring revealed whether participants tabbed to a different browser window during task performance (n1⁄4200). This behaviour was associated with poorer PAL performance (t 1⁄4 -2.09, df 1⁄4 161.5, p-value 1⁄4 0.03), greater RT variability (t 1⁄4 -3.48, df 1⁄4 119.6, p-value < 0.01) and younger age (t 1⁄4 3.4157, df 1⁄4 192.9, p-value <0.01). Conclusions: Behavioural metrics can be used to reliably identify lack of task engagement in web-based testing. Good task engagement is typically seen in older participants. A combination of detailed task behaviour analysis and monitoring technology is recommended in remote testing. Once these safeguards are in place, online testing is feasible and produces similar results to those obtained in supervised settings, making this technology suitable for remote assessment of cognitive function for recruitment and research purposes.

P3-127: Identification of cognitive decline using a longitudinal telephone screening versus brief, one-day computerized testing

and 100%; specificity: 82% and 87%; cut-off: 7.5 and 6.5) and AD from MCI (AUC: 0.89 and 0.91; sensitivity: 88% and 80%; specificity: 74% and 75%; cut-off 9.5 and 7.5). The test was less accurate to discriminate MCI from controls (AUC: 0.62 and 0.82; sensitivity: 75% and 95%; specificity: 54% and 50%; cut-off: 3.5 and 3.5). Conclusions: The SKT is subject to educational bias, and discriminates patients with AD from MCI and controls.