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Social isolation can cause dementia, says new UK study

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Social isolation is linked with changes in the brain structures associated with memory

Social isolation is directly linked with changes in the brain structures associated with memory, making it a clear risk factor for dementia, according to a new study carried out by scientists.

Setting out to investigate how social isolation and loneliness were related to later dementia, researchers at the University of Warwick, University of Cambridge and Fudan University used neuroimaging data from more than than 30,000 participants in the UK Biobank data set. Socially isolated individuals were found to have lower gray matter volumes of brain regions involved in memory and learning.

The results of the study are published online today (June 8, 2022) in Neurology, the medical journal of the American Academy of Neurology, in a paper entitled Associations of social isolation and loneliness with later dementia by Shen, Rolls, Cheng, Kang, Dong, Xie, Zhao, Sahakian and Feng (doi: 10.1212/WNL.0000000000200583).

The main conclusions of the study are:

Social isolation is an independent risk factor for dementia

Interdisciplinary study shows changes to brain structures associated with memory and cognitive function are directly linked to social isolation

Data shows that socially isolated are 26% more likely to develop later dementia

Implications for health and social care policy, in wake of COVID-19 pandemic during which people tend to get isolated

The study found that socially isolated individuals were shown to have a 26% increased likelihood of developing dementia.

Loneliness was also associated with later dementia, but that association was not significant after adjusting for depression, which explained 75% of the relationship between loneliness and dementia.

Therefore, relative to the subjective feeling of loneliness, objective social isolation is an independent risk factor for later dementia. Further subgroup analysis showed that the effect was prominent in those over 60 years old.

Professor Edmund Rolls, neuroscientist from the University of Warwick Department of Computer Science, said: “There is a difference between social isolation, which is an objective state of low social connections, and loneliness, which is subjectively perceived social isolation.

“Both have risks to health but we have been able to show that it is social isolation, rather than the feeling of loneliness, which is an independent risk factor for later dementia. This means it can be used as a predictor or biomarker for dementia in the UK,” he explained.

“With the growing prevalence of social isolation and loneliness over the past decades, this has been a serious yet underappreciated public health problem. Now, in the shadow of the COVID-19 pandemic there are implications for social relationship interventions and care – particularly in the older population,” Professor Edmunds added.

Professor Jianfeng Feng, from the University of Warwick Department of Computer Science, said: “We highlight the importance of an environmental method of reducing risk of dementia in older adults through ensuring that they are not socially isolated. During any future pandemic lockdowns, it is important that individuals, especially older adults, do not experience social isolation.”

Professor Barbara J Sahakian, of the University of Cambridge Department of Psychiatry, said: "Now that we know the risk to brain health and dementia of social isolation, it is important that the government and communities take action to ensure that older individuals have communication and interactions with others on a regular basis."