Loneliness and Social Isolation May Be Linked to Alzheimer’s Disease, Study Finds

A new research study has found that older, cognitively normal adults with elevated levels of cortical amyloid, the protein linked to Alzheimer’s, are much more likely to report feeling lonely and socially isolated regardless of their circumstances. These findings support the potential role of loneliness in preclinical Alzheimer’s disease.

The study, “Association of Higher Cortical Amyloid Burden With Loneliness in Cognitively Normal Older Adults,” was published online in JAMA Psychiatry. 

“We report a novel association of loneliness and cortical amyloid burden in cognitively normal older adults and present evidence for loneliness as a neuropsychiatric symptom relevant to preclinical Alzheimer’s disease,” Nancy J. Donovan, MD, lead author and associate psychiatrist at the Center for Alzheimer Research and Treatment at Brigham and Women’s Hospital in Boston, said in a press release.

The researchers enrolled 79 people who were cognitively normal and lived in a community with a mean age of 76.4. They were all enrolled in the Harvard Aging Brain Study.

In total, 22 people (28 percent) tested positive for the genetic risk factor for Alzheimer’s disease, and 25 people (32 percent) had cortical amyloid burden, as determined by Pittsburgh compound B-positron emission tomography.

With answers given in a four-point scale (from 1, never, to 4, often), self-reports of loneliness were evaluated with the three-item UCLA Loneliness Scale, which asks, “How often do you feel you lack companionship?”; “How often do you feel left out?”; and “How often do you feel isolated from others?”

In a range from 3 to 12, the highest score would indicate greater loneliness.

Before adjusting for age, sex, genetic Alzheimer’s carrier status, socioeconomic status, depression, anxiety, and social networks, participants scored their loneliness as a mean 5.3.

After the adjustment, participants with a higher amyloid burden were 7.5 times more likely to be classified as lonely compared to those without that amyloid burden. The link between this burden and that classification was also markedly stronger in carriers of Alheimer’s genetic risk factor.

“We are interested in the possibility that early brain changes due to Alzheimer’s disease may be associated with subtle changes in social perception or social reward that could predispose to feelings of loneliness,” Donovan said. “Alternatively, social interactions may be cognitively demanding in individuals who may be experiencing mild subjective cognitive changes due to early Alzheimer’s disease that might cause them to restrict their social activity and feel lonely.”

In light of this research, the authors suggest that the experience of feeling lonely and socially isolated may play a causative role in Alzheimer’s disease.

“It is also possible that the subjective experience of loneliness or detachment may promote amyloid accumulation, or there may be dynamic and reciprocal effects over time,” Donovan and her co-authors added.

Additional studies are planned to further assess whether the Alheimer’s genetic risk factor influences unidirectional or bidirectional associations of amyloid burden and loneliness over time.