Strategies to reduce the risk of developing dementia or delay its onset seem critical in today’s society where dementia-related neurodegenerative diseases are estimated to impact over 50 million adults worldwide. Among all the factors to prevent dementia that have been investigated, social engagement is associated with less cognitive decline and a lower risk of developing cognitive impairment. Within social engagement, different domains and aspects should be considered, i.e. social activity, social network size, marital status, social support and loneliness. Although social activity may provide stimuli that could help the brain develop the resilience that buffers against neurodegeneration, little is known about the impact that it has on the average age of dementia onset. In a recent study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, a team of researchers led by Dr Yi Chen from Rush Alzheimer’s Disease Center (Rush University Medical Center, Chicago, US) examined the associations of social activity with incident dementia and Mild Cognitive Impairment (MCI), with a particular focus on how different levels of social activity are associated to the age of MCI and dementia onset.
The study included 1,923 participants without dementia who are also part of the Rush Memory and Aging Project, an ongoing longitudinal study of conditions related to aging. The participants involved in this study were approximately 80 years old and had completed, on average, 15 years of education. Social activity was measured using a questionnaire that asked the participants whether or not they had engaged, over the previous year, in six social activities that involved social interaction, and how frequently. Cognitive function was then assessed using different tests that evaluate memory, among other cognitive functions. Over an average of five years, a total of 545 participants developed dementia, and 695 developed MCI. Higher levels of social activity were associated with a 38% lower risk of developing dementia. Loneliness was also associated with incident dementia, increasing the risk by 40%. There was also a strong association between social activity and the age of diagnosis. For the individuals who were less socially active, the mean age of dementia onset was 87.7 years whereas for those more socially active, this onset was delayed by almost five years. Similarly, social activity was associated with a 21% lower risk of developing MCI.
The mean age of MCI onset was 78.4 years for the least socially active, approximately three years earlier than for the most socially active participants. The team found that, in older adults and during an average of five years, individuals who were more socially active showed reduced rates of dementia and delayed onset. This five-year difference in the age of onset was also observed for the participants who developed MCI. Although the study does not provide the mechanism by which social activity impacts the development of cognitive problems, it provides important public health metrics for understanding the link between social activity and cognitive health. More studies, in more diverse populations, are needed to confirm these findings and to determine whether interventions aimed at increasing social activity later in life can prevent or delay cognitive impairment and decline.
https://alzjournals.onlinelibrary.wiley.com/doi/epdf/10.1002/alz.14316
