Cortical Thickness Correlates of Go/No-go and Motor Sequencing in Mild Cognitive Impairment and Suspected Alzheimer Disease Dementia.

BACKGROUND: While the cognitive hallmark of typical Alzheimer disease (AD) is impaired memory consolidation, increasing evidence suggests that the frontal lobes and associated executive functions are also impacted. OBJECTIVE: We examined two neurobehavioral executive function tasks and associations with cortical thickness in patients diagnosed with mild cognitive impairment (MCI), suspected AD dementia, and a healthy control group. METHODS: First, we compared group performances on a go/no-go (GNG) task and on Luria's Fist-Edge-Palm (FEP) motor sequencing task. We then examined correlations between neurobehavioral task performance and the thickness of frontal cortical regions, AD signature regions, broader unbiased brain regions, and white matter hyperintensities (WMH). RESULTS: Participants with MCI performed worse than healthy controls, but better than participants with suspected AD dementia on both tasks. Both GNG and FEP (to a slightly greater extent) tasks showed diffuse associations with most AD signature regions and multiple additional regions within the temporal, parietal, and occipital cortices. Similarly, both tasks showed significant associations with all other cognitive tasks examined. Of the frontal regions examined, only the middle frontal gyrus and pars opercularis were associated with performance on these tasks. Interactions between the precuneus and transtemporal gyri were most predictive of GNG task performance, while the interaction between superior temporal and lingual gyri was most predictive of FEP task performance. CONCLUSION: This study replicates difficulties with both GNG and FEP tasks in participants with MCI and AD dementia. Both tasks showed widespread associations with the cortical thickness of various brain structures rather than localizing to frontal regions, consistent with the diffuse nature of AD.

Changes in the Clinical Practice of Mental Health Service Providers Throughout the COVID-19 Pandemic: Longitudinal Questionnaire Study.

BACKGROUND: The COVID-19 pandemic impacted the practices of most mental health providers and resulted in a rapid transition to providing telemental health services, changes that were likely related to stay-at-home policies as well as increased need for services. OBJECTIVE: The aim of this study was to examine whether these changes to practice have been sustained over time throughout the course of the COVID-19 pandemic and whether there are differences among mental health provider type and setting. We hypothesized that there would be an increase in the number of patients seen in person after the initial surge of the pandemic in spring 2020 and subsequent discontinuation of stay-at-home policies, though with continued implementation of telemental health services across settings. METHODS: This study surveyed 235 of the 903 mental health providers who responded to a survey in spring 2020 (Time point 1) and at a 1-year follow-up in spring 2021 (Time point 2). Differences in practice adjustments, factors related to telemental health, and number of patients seen were examined across provider type (social worker, psychologist, neuropsychologist) and setting (academic medical center [AMC], community mental health, private practice, and Veterans Affairs hospital). RESULTS: From Time point 1 to Time point 2, there was a small but significant increase in the overall number of providers who were implementing telehealth (191/235, 81% to 204/235, 87%, P=.01) and there was a significant decline in canceled or rescheduled appointments (25%-50% in 2020 to 3%-7% in 2021, P<.001). Psychologists and providers working at AMCs reported decreased difficulty with telehealth implementation (P<.001), and providers working at AMCs and in private practice settings indicated they were more likely to continue telehealth services beyond spring 2021 (P<.001). The percent of time working remotely decreased overall (78% to 59%, P<.001), which was most notable among neuropsychologists and providers working at an AMC. There was an overall increase in the average number of patients seen in person per week compared with earlier in the pandemic (mean 4.3 to 8.7, P<.001), with no change in the number of patients seen via telehealth (mean 9.7 to 9.9, P=.66). CONCLUSIONS: These results show that the rapid transition to telemental health at the onset of the COVID-19 pandemic in spring 2020 was sustained over the next year, despite an overall increase in the number of patients seen in person. Although more providers reported returning to working on-site, over 50% of providers continued to use a hybrid model, and many providers reported they would be more likely to continue telemental health beyond spring 2021. This suggests the continued importance and reliance on telemental health services beyond the acute pandemic phase and has implications for future policies regulating the availability of telemental health services to patients.

More Similar than Different: Memory, Executive Functions, Cortical Thickness, and Glucose Metabolism in Biomarker-Positive Alzheimer's Disease and Behavioral Variant Frontotemporal Dementia.

Background: Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) are typically associated with very different clinical and neuroanatomical presentations; however, there is increasing recognition of similarities. Objective: To examine memory and executive functions, as well as cortical thickness, and glucose metabolism in AD and bvFTD signature brain regions. Methods: We compared differences in a group of biomarker-defined participants with Alzheimer's disease and a group of clinically diagnosed participants with bvFTD. These groups were also contrasted with healthy controls (HC). Results: As expected, memory functions were generally more impaired in AD, followed by bvFTD, and both clinical groups performed more poorly than the HC group. Executive function measures were similar in AD compared to bvFTD for motor sequencing and go/no-go, but bvFTD had more difficulty with a set shifting task. Participants with AD showed thinner cortex and lower glucose metabolism in the angular gyrus compared to bvFTD. Participants with bvFTD had thinner cortex in the insula and temporal pole relative to AD and healthy controls, but otherwise the two clinical groups were similar for other frontal and temporal signature regions. Conclusions: Overall, the results of this study highlight more similarities than differences between AD and bvFTD in terms of cognitive functions, cortical thickness, and glucose metabolism. Further research is needed to better understand the mechanisms mediating this overlap and how these relationships evolve longitudinally.

Frontal and temporal lobe correlates of verbal learning and memory in aMCI and suspected Alzheimer's disease dementia.

Alzheimer's disease is primarily known for deficits in learning and retaining new information. This has long been associated with pathological changes in the mesial temporal lobes. The role of the frontal lobes in memory in Alzheimer's disease is less well understood. In this study, we examined the role of the frontal lobes in learning, recognition, and retention of new verbal information, as well as the presence of specific errors (i.e., intrusions and false-positive errors). Participants included one hundred sixty-seven patients clinically diagnosed with amnestic mild cognitive impairment or suspected Alzheimer's disease dementia who were administered the California Verbal Learning Test and completed high-resolution MRI. We confirmed the role of the mesial temporal lobes in learning and retention, including the volumes of the hippocampus, entorhinal cortex, and parahippocampal gyrus. In addition, false-positive errors were associated with all volumes of the mesial temporal lobes and widespread areas within the frontal lobes. Errors of intrusion were related to the supplementary motor cortex and hippocampus. Most importantly, the mesial temporal lobes interacted with the frontal lobes for learning, recognition, and memory errors. Lower volumes in both regions explained more performance variance than any single structure. This study supports the interaction of the frontal lobes with the temporal lobes in many aspects of memory in Alzheimer's disease.

Procedural learning and retention relative to explicit learning and retention in mild cognitive impairment and Alzheimer's disease using a modification of the trail making test.

Amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) dementia are characterized by pathological changes to the medial temporal lobes, resulting in explicit learning and retention reductions. Studies demonstrate that implicit/procedural memory processes are relatively intact in these populations, supporting different anatomical substrates for differing memory systems. This study examined differences between explicit and procedural learning and retention in individuals with aMCI and AD dementia relative to matched healthy controls. We also examined anatomical substrates using volumetric MRI. Results revealed expected difficulties with explicit learning and retention in individuals with aMCI and AD with relatively preserved procedural memory. Explicit verbal retention was associated with medial temporal cortex volumes. However, procedural retention was not related to medial temporal or basal ganglia volumes. Overall, this study confirms the dissociation between explicit relative to procedural learning and retention in aMCI and AD dementia and supports differing anatomical substrates.