Loneliness increases the risk of dementia.

Japanese researchers have been investigating how social isolation and loneliness affect the brains of older adults. They studied 8,896 Japanese individuals aged 65 and older who underwent MRI scans.

Fewer Social Contacts – Smaller Brain Volume

Participants in the study were asked how often they interacted with relatives and friends who do not live with them. For instance, they were questioned about whether they met in person or spoke on the phone. Respondents could choose from the following options: daily, several times a week, several times a month, or rarely.

Those with the lowest levels of social contact had significantly smaller brain volumes compared to those with the highest levels of social interaction. Their total brain volume, which is the sum of gray and white matter as a percentage of total cranial volume, was 67.3% in the group with the least contact, compared to 67.8% in the group with the most contact.

They also exhibited reduced brain volume in specific areas, including the hippocampus and amygdala, which play crucial roles in memory and are associated with dementia. The hippocampus is one of the first areas affected by Alzheimer’s disease.

It’s possible that a lack of social contact accelerates the gradual brain shrinkage that occurs with aging. However, isolated individuals also tend to lead unhealthier lifestyles, which can be detrimental to their brain health.

The senior author of the study, Dr. Toshiharu Ninomiya, states that social isolation is becoming an increasingly pressing issue for older adults. The findings suggest that providing support to help individuals maintain connections with others could be beneficial in preventing brain atrophy and the development of dementia.

Loneliness-Induced Depression Partially Explains the Findings

As reported by the Daily Mail, the link between a lack of social contacts and reduced brain volume found in older Japanese adults persisted even when accounting for other factors that could influence brain health. This means the correlation holds true regardless of factors such as body weight, smoking habits, alcohol consumption, and the presence of diabetes.

However, researchers note that individuals experiencing brain volume loss may notice changes in personality, such as becoming more apathetic. This can lead to them seeing people less frequently, which in turn contributes to further brain changes.

Socially isolated individuals in the study also had more small areas of damage in the brain known as white matter lesions compared to those with frequent social interactions. The proportion of intracranial volume made up of white matter lesions was 0.3% for the socially isolated group, compared to 0.26% for the most socially connected group.

Researchers found that depression, which is linked to reduced brain volume, partially explains the relationship between social isolation and brain volume. However, depressive symptoms accounted for only a small portion of this outcome.

Further Samples Needed for Generalized Conclusions

Dr. Ninomiya noted that this study does not establish that social isolation directly causes brain atrophy. However, some observations indicated that keeping older adults in socially stimulating groups halted or even reversed brain volume loss and improved thinking and memory skills. Therefore, it is quite possible that interventions aimed at reducing social isolation could prevent brain volume loss and the dementia that often follows.

It is important to note that the study sample consisted entirely of older Japanese individuals. Thus, further observations are needed to determine whether the previously obtained conclusions apply to people of other ethnic backgrounds and younger populations.