Midlife loneliness is a risk factor for Dementia and Alzheimer's disease

Loneliness is a subjective feeling resulting from a perceived discrepancy between desired and actual social relationships. Although loneliness does not itself have the status of a clinical disease, it is associated with a range of negative health outcomes, including sleep disturbances, depressive symptoms, cognitive impairment, and stroke. Still, feeling lonely may happen to anyone at some point in life, especially under extreme and unresolved quickly circumstances such as the Covid-19 lockdowns. Yet, people differ in how long--or how "persistent"--they feel lonely for. Thus, it may be that people who recover from loneliness will experience different long-term consequences for their health than people who are lonely for many years.

In an effort to shed light on the relationship between these different forms of loneliness (transient and persistent loneliness) and the incident of AD, researchers from Boston University School of Medicine (BUSM) examined data involving cognitively normal adults from the Framingham Heart Study. Specifically, they investigated whether persistent loneliness more strongly predicted the future development of dementia and AD than transient loneliness. They also wanted to see whether this relationship was independent from depression and established genetic risk factors for AD, such as the Apolipoprotein ε4 (APOE ε4) allele.

After taking effects of age, sex, education, social network, living alone, physical health and genetic risk into account, persistent loneliness was associated with higher risk, whereas transient loneliness was linked to lower risk of dementia and AD onset after 18 years, compared with no loneliness.

"Whereas persistent loneliness is a threat to brain health, psychological resilience following adverse life experiences may explain why transient loneliness is protective in the context of dementia onset," explained corresponding author Wendy Qiu, MD, PhD, professor of psychiatry and pharmacology & experimental therapeutics at BUSM. In light of the current pandemic, these findings raise hope for people who may suffer from loneliness now, but could overcome this feeling after some time, such as by using successful coping techniques or following a policy change in the physical distancing regulations.

According to the researchers, these results motivate further investigation of the factors that make individuals resilient against adverse life events and urges to tailor interventions to the right person at the right time to avert persistency of loneliness, promote brain health and AD prevention.