Introduction: The coronavirus disease 2019 (COVID-19) pandemic has drastically disrupted daily routines, imposing rules such as social distancing and isolation that limit flexibility in one's social environment. These restrictions may spur the rate of cognitive decline in older adults, increasing the risk of Alzheimer's disease (AD) and exacerbating symptoms such as memory loss, impaired spatial awareness and language. These mandates may also hinder physical activity engagement, further increasing the risk of mental health problems and accelerating cognitive decline. As social interaction and physical activity form components of cognitive reserve, older adults may now face a higher risk of AD and faster AD progression. This paper will review the literature examining how the COVID-19 pandemic has affected the rate of cognitive decline in older adults in terms of AD pathology in three domains: social, physical, and psychological factors. Methods: This systematic review summarizes the literature examining the relationship between social engagement, physical activity, and psychological well-being on cognitive decline in older adults. Electronic databases (PubMed, ScienceDirect, Web of Science, Google Scholar, and PsycINFO) were searched with the following keywords: "COVID-19, social isolation, Alzheimer's, cognitive decline, physical activity, social, psychological". Results: Social engagement and physical activity can reduce the rate of cognitive decline and decrease the risk of AD and other dementias. Given that social, physical, and psychological factors have been impacted by pandemic restrictions, studies show this may result in greater cognitive decline in the years to follow. This is exacerbated due to the comorbidity between psychological distress and AD symptoms. Discussion: The results of this study can be further explored to develop an intervention that can mitigate the negative effects of pandemic restrictions in individuals with AD. Overall, preventative strategies targeting factors of cognitive reserve should be urgently implemented for disadvantaged populations with a focus on older adults.
Conclusion:Clarifying the relationship between the COVID-19 restrictions and its effects on cognitive decline in AD will improve the health and well-being of older adults in the present and future. Understanding these effects on cognitive decline in AD has broader implications regarding individual responses to COVID-19 restrictions, and its associations with social engagement, physical activity, and psychiatric disorders in aging.