Lonely children have an increased risk of dementia and cognitive decline in adulthood, study finds

An analysis of the China Health and Retirement Longitudinal Study data found that individuals who reported experiencing loneliness as children had a 41% higher risk of dementia in adulthood. They also tended to experience faster age-related cognitive decline. The paper was published in JAMA Network Open.

As people reach advanced age, their cognitive abilities start to decline. This is very subtle at first, but may become faster as a person ages. Processing speed and working memory are usually the most affected, while cognitive capacities based on experience and attained knowledge tend to be the least affected. This is called age-related cognitive decline. It is a normal part of aging and is not, by itself, indicative of any pathology.

In contrast, dementia is a pathological condition in which cognitive decline becomes fast and very severe. The most common form of dementia is Alzheimer’s disease, which involves progressive brain cell loss and disruptions in key neural networks. Unlike normal age-related cognitive decline, dementia affects core functions like language, reasoning, and memory stability. It results in extensive structural changes to the brain, including shrinkage of the hippocampus.

While there is no cure for dementia, research suggests that physical activity, cognitive engagement, and social interaction can help slow age-related decline and reduce dementia risk. As human lifespans increase, more and more people reach an age in which they experience cognitive decline and dementia. This has made research into factors that affect the risk of dementia and the pace of age-related cognitive decline a priority for many.

Study author Jinqi Wang and colleagues wanted to investigate whether childhood loneliness is associated with cognitive decline and dementia risk in adulthood and whether adult loneliness mediates or modifies these associations. They defined childhood loneliness as self-reported frequent feelings of loneliness and the absence of close friendships before the age of 17.
These researchers analyzed data from the China Health and Retirement Longitudinal Study (CHARLS).

The CHARLS is a nationwide study of Chinese adults aged 45 years and older. The study recruited a total of 17,707 participants from 28 provinces in China back in 2011 and collected follow-up data periodically. While data was collected through 2020, the researchers restricted their analysis to follow-ups through 2018 to avoid bias related to the COVID-19 pandemic. Information about childhood loneliness was collected through face-to-face interviews during the 2014 data collection.

As some participants dropped out of the study and some did not participate in all surveys and interviews, the authors of this study used data from 13,592 participants who had all the needed results. Their average age at the start of the study was 58 years. Approximately 53% of them were women.

Results showed that, compared to participants who did not report being lonely in childhood, participants who reported being lonely as children tended to experience faster cognitive decline. They also had a 41% higher risk of dementia compared to their peers who were not lonely as children.

These associations remained even after study authors controlled for loneliness in adulthood. However, adult loneliness was a possible mediator of a small part (8.5%) of the association between childhood loneliness and cognitive decline. It was also a possible mediator of 17.2% of the association between childhood loneliness and dementia.

“These findings suggest that childhood loneliness may serve as an independent risk factor for later-life cognitive decline and dementia, highlighting the need for early interventions to mitigate its long-term implications for cognitive health throughout the life course,” study authors concluded.

The study contributes to the scientific understanding of the risk factors for dementia and accelerated cognitive decline in advanced age. However, it should be noted that childhood loneliness data was not collected in childhood, but was based on self-reports participants gave when they were already over 45 years of age. This leaves room for recall bias to have affected the results.

The paper, “Childhood Loneliness and Cognitive Decline and Dementia Risk in Middle-Aged and Older Adults,” was authored by Jinqi Wang, Danyang Jiao, Xiaoyu Zhao, Yixing Tian, Haibin Li, Xia Li, Chen Sheng, Lixin Tao, Hui Chen, Zhiyuan Wu, and Xiuhua Guo.