Effects even without a feeling of loneliness: Those who live socially isolated have a significantly higher risk of dementia in old age, as a large long-term study reveals. Accordingly, a lack of contact leads to a loss of gray matter in the brain over time and increases the risk of dementia by around 26 percent.

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However, these consequences of social isolation are independent of whether those affected feel subjectively lonely or not, as the researchers report in the specialist journal “Neurology”.

Man is a social being – our biology and psyche are designed for social stimulation and contacts. But especially nowadays, more and more people are living in social isolation.

This also has consequences for health: loneliness and social isolation lead to sleep disorders, stress, weaken the immune system and can promote inflammation, as studies have shown. Brain activity is also altered in socially isolated people.

Now a large long-term study shows that social isolation also increases the risk of dementia. Chun Shen from Fudan University in China and his colleagues evaluated the data from more than 460,000 participants in the long-term UK biobank study.

Over a period of around twelve years, these included the health and living conditions of the test subjects, who were on average 57 years old at the start of the study – and thus also whether they were socially isolated, felt lonely and whether they suffered from dementia.

It turned out that almost 5,000 participants fell ill with dementia during the course of the study – and people who stated at the beginning of the study that they had hardly any contacts and were socially isolated were more frequently affected. Specifically, the risk of dementia increased by 26 percent due to social isolation, as Shen and his team report.

The surprising thing about it: This increased risk of dementia is independent of whether those affected feel subjectively lonely or not. “There is a difference between the objective lack of social contact and the subjective feeling of loneliness,” explains co-author Edmund Rolls from the University of Warwick. “Both have health implications, but we were able to show that actual isolation, rather than feeling lonely, is an independent risk factor for dementia.”

This was confirmed by the results of the brain scans: “Socially isolated participants had a lower volume of gray matter in the frontal lobe, the temporal lobe, the hippocampus and other brain regions,” reports the team.

These areas are closely linked to learning and memory. It was also shown that those who had hardly any contact at the beginning of the study also mentally deteriorated faster.

More detailed analyzes also revealed that some genes that are important for the mitochondria and thus the energy supply of the brain cells were downregulated in the neurons of socially isolated people. Some of the genes that are suppressed in Alzheimer’s were also less active in these participants.

According to the researchers, this confirms that a lack of social contacts affects brain health even if those affected do not subjectively suffer from loneliness. “Given the increasing prevalence of social isolation and loneliness in recent decades, this is a serious but underappreciated public health issue,” says Rolls.

It is therefore particularly important for older people to maintain social contacts and not to live in isolation in everyday life. “Now that we better understand the impact of social isolation on brain health, it is important that communities and governments act,” says co-author Barbara Sahakian from the University of Cambridge.

Care must be taken to ensure that older people also have more opportunities to have regular contact with others.

Quelle: University of Warwick

This article was written by Nadja Podbregar

The original of this article “Increased risk of dementia: Social isolation as an underestimated factor” comes from scinexx.