Long-term feelings of loneliness may worsen memory function and speed up cognitive decline, particularly among women and older adults, according to a new study published in Alzheimer's & Dementia.

Study details and key findings

For the study, researchers from the University of Michigan School of Public Health used data from the National Institute of Aging's Health and Retirement study to create a longitudinal model that measured the association between loneliness and memory function in participants.

The study included 9,032 adults ages 50 and older. Researchers assessed participants' loneliness status biennially between 1996 and 2004. The duration of loneliness was classified by the number of time points participants answered they were lonely (0, 1, 2, 3+ time points).

Of the participants, 61.04% did not report being lonely at any time, 17.99% reported being lonely at one point in time, 9.13% reported being lonely at two points in time, and 11.84% reported being lonely at three or more points in time.

Next, researchers assessed episodic memory between 2004 and 2016 using immediate and delayed recall of a 10-word list read aloud by an interviewer. For participants who were too impaired to participate in interviews, a proxy interview was conducted with a family member or friend to assess the participants' overall memory.

Researchers found that a longer duration of loneliness was associated with both lower memory scores and faster cognitive decline. This association was strongest among women, as well as participants ages 65 and older.

"Our study finds that there is an association between loneliness and memory aging, suggesting that society, family members, or friends and neighbors should pay attention to older adults' emotional support or social support as we find that loneliness has a tremendous effect on the individual's memory aging," said Xuexin Yu, one of the study's authors. "And, given the increasing prevalence of loneliness, particularly during the COVID pandemic, it's very important to take care of older adults' loneliness status."

Commentary

According to Steve Cole, a professor of medicine at the Semel Institute for Neuroscience and Human Behavior at the University of California, Los Angeles, loneliness can contribute to and exacerbate several other diseases.

"The biology of loneliness can accelerate the buildup of plaque in arteries, help cancer cells grow and spread, and promote inflammation in the brain leading to Alzheimer's disease," Cole said. "Loneliness promotes several types of wear and tear on the body."

In addition, Elena Portacolone, an associate professor of sociology at the Institute for Health and Aging at the University of California, San Francisco, noted that structural factors, particularly in high-crime neighborhoods, may also impact older adults' social isolation and subsequently their health.

"The primary takeaway from this research is that interventions to increase older adults' social integration should address not only their behaviors, but their overall surroundings," Portacolone said. "We need to concentrate our attention on the influence of social policies, institutions, and ideologies in the everyday experience of isolated older adults." (Ray, HealthLeaders, 8/25; Yu et al., Alzheimer's & Dementia, 8/3)