Is loneliness associated with a higher risk of Alzheimer's? A study published online Nov. 2, 2016, by JAMA Psychiatry examined 79 adults, average age 76, with no signs of Alzheimer's or dementia, to determine if amyloid levels in the brain (a marker of developing Alzheimer's) was linked with a person's sense of loneliness. Using data from the Harvard Aging Brain Study, the researchers found that 32% of the people tested positive for high amyloid levels, especially in the cerebral cortex, a part of the brain that plays a key role in memory, attention, perception, and thought. People in this group also were almost eight times more likely to be classified as lonely compared with those in the amyloid-negative group.

The study could not determine whether loneliness causes higher amyloid or higher amyloid leads to greater loneliness. However, it's possible that individuals with high levels may experience subtle changes in social perception that predispose them to feelings of loneliness, according to lead researcher Dr. Nancy J. Donovan of Harvard-affiliated Brigham and Women's Hospital.