WASHINGTON, DC—Loneliness is a risk factor for accelerated cognitive decline in older adults, according to research presented at the 2015 Alzheimer’s Association International Conference. Although loneliness and depression appear closely linked, loneliness may have independent effects on cognition, said Nancy Donovan, MD, an Associate Psychiatrist at Brigham and Women’s Hospital and an Instructor in Psychiatry at Harvard Medical School in Boston.
Prior studies have found that loneliness is associated with increased progression to dementia, but researchers are not sure whether loneliness causes or is a consequence of cognitive decline. To examine the relationship between loneliness and cognitive function, Dr. Donovan and colleagues analyzed data for 8,311 adults who participated in the US Health and Retirement Study from 1998 to 2010. Participants were age 65 or older and had biennial assessments of loneliness, depression, and cognitive function, including the eight-item version of the Center for Epidemiologic Studies Depression Scale (CES-D), Telephone Interview for Cognitive Status, Informant Questionnaire on Cognitive Decline in the Elderly, and a word list memory task. Participants were considered lonely if they agreed that they felt lonely much of the time during the past week, which was one of the questions on the CES-D.
Researchers controlled for sociodemographic factors, health conditions, depression, and social network. Social network was determined by whether people were married or living with a partner, had contact with friends or neighbors at least weekly, had contact with a child at least weekly, and participated in a volunteer activity.
Eighteen percent of the participants were classified as lonely at baseline. Baseline loneliness was associated with a 20% faster rate of cognitive decline over 12 years, independent of sociodemographic factors, social network, health, and baseline depression, compared with participants who were not lonely. Depressive symptoms similarly were related to accelerated cognitive decline. In a model that evaluated the effects of loneliness and depression, the effect of loneliness was reduced and became marginally significant. Cognition was not a significant predictor of loneliness when researchers controlled for baseline depression.
“This work highlights the need to design and target effective treatments for older adults who experience loneliness and depression and those who are at high risk,” Dr. Donovan said.