Boston: The feeling of loneliness may be linked to amyloid levels in the brain - an indicator of preclinical Alzheimer's disease, scientists have found. Using data from a study of 79 cognitively normal adults to examine whether cortical amyloid levels in the brain, a marker of preclinical Alzheimer's disease, was associated with self-reported loneliness.
Alzheimer's disease (AD) is a process that moves through preclinical, mild cognitive impairment and dementia stages before it leads to progressive neuropsychiatric, cognitive and functional declines. Loneliness has been associated with cognitive and functional decline and an increased risk of AD dementia.
Nancy J Donovan, from Brigham and Women's Hospital and Harvard Medical School in the US used imaging as a measure of cortical amyloid levels in the brain and a loneliness scale to indicate levels of loneliness. The study included 43 women and 36 men with an average age of about 76.
Of the participants, 22 (28 per cent) were carriers of the genetic risk factor apolipoprotein E e4 (APOEe4) and 25 (32 per cent) were in the amyloid-positive group based on volume in imaging. The participants' average loneliness score was 5.3 on a scale of 3 to 12.
Researchers found that higher cortical amyloid levels were associated with greater loneliness after controlling for age, sex, APOEe4, socioeconomic status, depression, anxiety and social network. Participants in the amyloid-positive group were 7.5 times more likely to be classified as lonely then non-lonely compared with individuals in the amyloid-negative group.
The association between high amyloid levels and loneliness also was stronger in APOEe4 carriers than in noncarriers, researchers said. "We report a novel association of loneliness and cortical amyloid burden in cognitively normal adults and present evidence for loneliness as a neuropsychiatric symptom relevant to preclinical AD," they said.
"This work will inform new research into the neurobiology of loneliness and other socioemotional changes in late life and may enhance early detection and intervention research in AD," they added. The study was published in the JAMA Psychiatry journal.
