AbstractThe burden imposed by the COVID-19 pandemic deferentially interferes with the outcomes of clinical trials of aging… (see more) and dementia. We examined the impact of the lockdown on cognitive impairment due to Alzheimer’s Disease (AD), anxiety, and COVID-19-related stress in participants from the Translational Biomarkers In Aging and Dementia (TRIAD) cohort using neuropsychiatric assessments, tau and amyloid PET. We found that, before the lockdown, anxiety was higher in cognitively impaired individuals (CI) and positively associated with brain tau load. However, during the lockdown, anxiety increased only in the cognitively unimpaired (CU) and was positively associated with COVID-19 related stress. Interestingly, we found that in patients, tau load was anti-correlated with higher anxiety during lockdown. Our findings contribute to a framework for interpreting the effects of the pandemic on neuropsychiatric symptoms among clinical trial participants. Collectively, our results suggest that caregivers are more vulnerable to external stressors than patients.