Why are we excited about being in big bands at festivals, jubilees, and other public events? According to the social brain hypothesis, this is because the human brain has specifically evolved to support social interactions. Studies have shown that belonging to a group can improve well-being and increase life satisfaction.
Unfortunately, many people are alone or socially isolated. And if the human brain really evolved for social interaction, we should expect that to affect it significantly.
Our recent study published in Neurologyshows that social isolation is linked to changes in brain structure and cognition – the mental process of acquiring knowledge – it even carries an increased risk of dementia in older people.
There is already plenty of evidence supporting the social brain hypothesis. One study mapped brain regions associated with social interaction in about 7,000 people.
He showed that brain regions consistently involved in various social interactions are strongly linked to networks that support cognition, including the default mode network (which is active when we are not focusing on the outside world), the salience network (which helps us select what to pay attention to), the subcortical network (involved in memory, emotion and motivation) and the central executive network (which allows us to regulate our emotions).
We wanted to take a closer look at how social isolation affects gray matter – brain regions in the outer layer of the brain, made up of neurons. So we looked at data from almost 500,000 people from the UK Biobank, with an average age of 57.
People were classified as socially isolated if they lived alone, had social contact less than once a month, and participated in social activities less than once a week.
Our study also included neuroimaging (MRI) data from approximately 32,000 people. This showed that socially isolated people had lower cognition, including in terms of memory and reaction times, and lower gray matter volume in many parts of the brain.
These areas included the temporal region (which processes sound and helps encode memory), the frontal lobe (which is involved in attention, planning and complex cognitive tasks) and the hippocampus – a key area involved in learning and memory, which is usually impaired early in Alzheimer’s disease.
We also found a link between lower gray matter volumes and specific genetic processes involved in Alzheimer’s disease.
There were follow-ups with the participants 12 years later. This showed that those who were socially isolated, but not alone, had a 26% increased risk of dementia.
Social isolation needs to be examined further in future studies to determine the exact mechanisms behind its profound effects on our brains. But it is clear that if you are isolated, you may be suffering from chronic stress. This in turn has a major impact on your brain, as well as your physical health.
Another factor may be that if we don’t use certain areas of the brain, we lose some of their function. A study of taxi drivers showed that the more routes and addresses they memorized, the greater the volume of the hippocampus. It’s possible that if we don’t regularly engage in social discussions, for example, our use of language and other cognitive processes, such as attention and memory, will decline.
It can affect our ability to perform many complex cognitive tasks – memory and attention are essential for complex cognitive thinking in general.
We know that a strong set of thinking skills throughout life, called the “cognitive reserve”, can be built up by keeping your brain active. A good way to do this is to learn new things, like another language or a musical instrument.
Cognitive reserve has been shown to improve the course and severity of aging. For example, it may protect against a number of mental health illnesses or disorders, including forms of dementia, schizophrenia and depression, especially following head trauma.
There are also lifestyle items that can improve your cognition and well-being, including healthy eating and exercise. For Alzheimer’s disease, there are some pharmacological treatments, but the effectiveness of these must be improved and the side effects must be reduced.
It is hoped that in the future there will be better treatments for aging and dementia. One avenue of research in this regard concerns exogenous ketones – an alternative energy source to glucose – which can be ingested via nutritional supplements.
But as our study shows, tackling social isolation could also help, especially among older people. Health authorities should do more to check who is isolated and organize social activities to help them.
When people are unable to interact in person, technology can provide a substitute. However, it may be more applicable to younger generations who are familiar with using technology to communicate. But with training, it can also be effective in reducing social isolation in older people.
Social interaction is extremely important. A study found that the size of our social group is actually associated with the volume of the orbitofrontal cortex (involved in social cognition and emotions).
But how many friends do we need? Researchers often refer to “Dunbar’s number” to describe the size of social groups, finding that we are unable to maintain more than 150 relationships and typically only manage five close relationships.
However, some reports suggest a lack of empirical evidence surrounding Dunbar’s number and further research on the optimal size of social groups is needed.
It’s hard to argue that humans are social animals and derive pleasure from connecting with others, regardless of age. But, as we are increasingly discovering, it is also crucial for the health of our cognition.
Barbara Jacquelyn Sahakian, Professor of Clinical Neuropsychology, University of Cambridge; Christelle Langley, Postdoctoral Research Associate, Cognitive Neuroscience, University of Cambridge; Chun Shen, Postdoctoral Researcher, Fudan University, and Jianfeng Feng, Professor of Science and Technology for Brain-Inspired Intelligence, Fudan University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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