MRI scans done on patients measured if loneliness is associated with levels of amyloid proteins in the brain, which researchers suggest could be an indication of preclinical Alzheimer’s disease and ultimately aid in intervention research.

“Loneliness is a perceived state of social and emotional isolation that has been associated with cognitive and functional decline and an increased risk of incident [Alzheimer’s disease] dementia,” Nancy J. Donovan, MD, of Brigham and Women’s Hospital, Harvard Medical School, Boston, and colleagues wrote.

Researchers studied 79 community dwelling and cognitively normal adults, free from active, major psychiatric disorders, 43 women and 36 men with an average age of 76.

Brain imaging was used to measure amyloid protein levels in cortical areas of the participants’ brains, including the frontal, lateral temporal and lateral, and medial parietal regions.

“Twenty-two (28 percent) had positive APOEε4 carrier status, and 25 (32 percent) were in the amyloid-positive group with cortical PiB distribution volume ratio greater than 1.2,” wrote Donovan and colleagues. 

The authors reported that a higher cortical amyloid burden were associated with a stronger sense of loneliness after controlling for age, sex, APOEε4, socioeconomic status, depression, anxiety and social network.

Individuals who were amyloid-positive were 7.5 times more likely to be classified as lonely than non-lonely, compared to those who were amyloid-negative. 

The authors also used the UCLA Loneliness Scale, a self-rated instrument that has been implemented in numerous epidemiologic studies of aging, to indicate levels of loneliness for each individual.

The average loneliness score of the participants was 5.3 on a scale of 3 to 12.

“In a community-based sample of cognitively normal older people, we found that higher in vivo cortical amyloid burden was associated with greater feelings of loneliness, suggesting that loneliness is a novel neuropsychiatric symptom in preclinical Alzheimer’s disease,” the authors wrote.