Chronic loneliness may be hidden risk for early cognitive decline, study finds

Feeling persistently lonely in young or middle adulthood may do more than hurt emotionally—it could also put your brain at risk. A new study from Penn State University, published in BMC Public Health, suggests that chronic loneliness may be an early warning sign of cognitive decline, even in people as young as 25, Azernews reports.

Researchers tracked 172 adults aged 25 to 65 over a two-year period as part of the ESCAPE Project (Effects of Stress on Cognitive Aging, Physiology, and Emotion). Participants completed cognitive “brain games” on their smartphones five times a day for two weeks during each of the study’s three waves. They also regularly completed surveys measuring feelings of loneliness.

While most people got better at the brain games over time—likely due to practice—the chronically lonely participants did not. This lack of improvement may indicate slower cognitive processing and a reduced ability to adapt or learn over time, which could signal early cognitive decline.

“Loneliness is a natural and universal feeling, but when it becomes chronic, it can start to damage your cognitive health,” said Dr. Jee eun Kang, lead author of the study and a postdoctoral scholar at the Penn State Center for Healthy Aging.

Chronic loneliness in this study was defined as repeatedly scoring in the highest range of loneliness in at least two of the study’s three waves. Participants responded to statements like “I feel left out” on a five-point scale, allowing researchers to capture the depth and duration of their social disconnection.

Dr. Martin Sliwinski, co-author of the study and director of the Penn State Center for Healthy Aging, emphasized how concerning these findings are. “People typically get better at cognitive tasks the more they do them. The fact that lonely individuals didn’t show that improvement suggests their cognitive systems may not be as adaptable,” he said.

The findings raise a red flag: chronic loneliness could be a risk factor for neurodegenerative diseases later in life—especially since cognitive decline without improvement on repeated testing has also been seen in older adults at the early stages of such conditions.

But there’s good news too: the earlier people start prioritizing social and cognitive health, the better their outcomes may be. “It’s like saving for retirement,” said Sliwinski. “If you start early, you’ll be in much better shape later on.”

Fighting loneliness, especially in today’s fast-paced world, can be challenging. But researchers say that small, intentional steps—like setting regular social plans, being present in conversations, and reaching out even when it feels hard—can make a real difference.

“Loneliness can be a signal to make a change,” said Kang. “Even if it’s difficult, learning how to build and maintain social connections is vital—not just for happiness, but for long-term brain health.”