Social isolation increases risk of dementia

A huge 12-year study involving 30,000 participants has demonstrated that social isolation and loneliness can lead to later dementia.

An interdisciplinary research study published in the journal Neurology has linked social isolation to a higher risk of dementia. The study found that socially isolated people are 26% more likely to develop dementia later in life.

Social isolation, a state of being cut off from social networks, affects a significant number of people, especially older adults. It puts them at risk of serious medical health conditions like dementia, a public health problem often associated with old age.

Researchers at the University of Warwick, University of Cambridge and Fudan University investigated the relationship between social isolation and loneliness to later dementia.

The Covid-19 pandemic intensified social isolation across the world. This made it easier for researchers to identify the socially isolated and provide resources to help them make stronger connections in their community. 

The results of the study were published in a paper titled Associations of Social Isolation and Loneliness With Later Dementia, authored by Shen, Rolls, Cheng, Kang, Dong, Xie, Zhao, Sahakian, and Feng.

The effects of social isolation

The study analysed data from more than 460,000 people across the United Kingdom with an average age of 57. It followed them for nearly 12 years before the Covid-19 pandemic began. Of that number, almost 5,000 people developed “all-cause dementia” during the study.

The researchers collected neuroimaging data from more than 30,000 participants. Participants also shared survey data, their physical and biological measurements, and took thinking and memory tests to assess their cognitive function.

To determine social isolation, they were asked three questions about their level of social contact with other individuals: whether they lived with others, had visits with family and friends at least once a month, or participated in social activities at least once a week. Participants who answered in the negative to at least two of these questions were considered socially isolated.

The data collected showed changes in brain structures associated with memory and cognitive function. It found that individuals who reported higher levels of social isolation had lower grey matter volumes of brain regions involved in memory and learning. This meant that social isolation was a clear, independent risk factor and early indicator for dementia.

Other risk factors contributing to dementia

Using data from the UK Biobank, the researchers used modelling techniques to investigate the relative association of social isolation and loneliness with incident all-cause dementia. 

Professor Edmund Rolls from the University of Warwick’s Department of Computer Science outlined the key difference between social isolation and loneliness. Social isolation, the neuroscientist said, is an objective state of low social connections, while loneliness is subjectively perceived social isolation.

Researchers analysed other risk factors including age, sex, socio-economic factors, chronic illness, lifestyle (alcohol intake and smoking), APOE genotype, and conditions like depression and loneliness. Loneliness, although another possible risk factor for dementia, showed no strong correlation with dementia. This is because depression explained 75% of the relationship between loneliness and dementia. 

By using the extensive data from the UK Biobank, the researchers were able to show that, although both have risks to a person’s health, social isolation is an independent risk factor for later dementia, not the feeling of loneliness. This suggested that isolation may be an independent early indicator of an increased risk of later dementia.

A problem to public health

The study raised major concerns about the growing prevalence of social isolation and loneliness over the past decades, which presented a serious yet underappreciated public health problem. The problem was exacerbated by the Covid-19 pandemic, particularly in the older population.

A 2020 report from the National Academies of Sciences, Engineering and Medicine (NASEM) said almost 25% of adults over 65 years are socially isolated. These older adults are more likely to face factors such as living alone, losing family and friends, and experiencing chronic illness, putting them at an increased risk for social isolation.

With more knowledge of the risks of social isolation to brain health and dementia, steps need to be taken to protect older individuals from these effects.

Combating social isolation and its effects

As humans are generally social by nature, high-quality social relationships can help people live longer, healthier lives. Hence, those who may be at risk of social isolation need to be assessed periodically and provided with community resources that can improve their social interactions.

Researcher Professor Jianfeng Feng from the University of Warwick Department of Computer Science highlighted the importance of an environmental method of reducing the risk of dementia in older adults by ensuring they are not socially isolated. He said it is important that individuals, especially older adults who face a greater risk of dementia, do not experience social isolation.

Fortunately, people — even those who prefer to be alone — can make some simple changes to mitigate the negative effects of isolation. Many individuals turn to technology to complement real-life social interactions and find practical ways to stay connected and alleviate loneliness and social isolation.

Social media and messaging applications have also provided a means for people to connect all over the world. Apps like TikTok, for instance, provide entertainment for individuals across different age brackets, and people can download Tik Tok videos they like to watch again later or share with others.

Psychologist Jo Hemmins said the app provides a temporary oasis for many, and a 15-second video can provide you with a short burst of the feel-good hormone dopamine. Some organisations like AARP also offer helpful resources to help seniors identify and combat loneliness and social isolation and improve their quality of life.

According to Professor Barbara J. Sahakian from the University of Cambridge Department of Psychiatry, there is a need for the government and communities to take action to ensure that older individuals regularly communicate and interact with others.

Chidirim Ndeche

Chidirim Ndeche is a reporter at Breakthrough.

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