To evaluate neuropsychiatric symptoms in patients with Alzheimer’s disease (AD) and their association with cognition and functionality during lockdown of the COVID-19’s first wave. We included 91 patients and caregivers of people with AD from a memory clinic. The RUDAS, M@T, and CDR were administered to patients and NPI/ADCS-ADL to caregivers. Baseline and lockdown measurements scales were analyzed to compare the frequencies at baseline versus lockdown and conditional Odds Ratio (ORc) was calculated for the neuropsychiatric symptoms. During the pandemic, significant increase in the number of cases was observed in depression (23%), agitation (36.8%), aberrant motor activity (12%), sleep disorders (26.3%), and appetite change (12.1%). In worsening of pre-existing symptoms, the most frequent were delusions (75%), followed by sleep disorders (71.7%). Lockdown induces a rapid increase of neuropsychiatric symptoms affecting cognitive symptoms and functionality of Peruvian patients with AD.