Socially isolated people have differently wired brains and poorer cognition


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Summary: Social isolation is associated with changes in brain structure and cognitive deficits. In addition, social isolation can increase the risk of developing dementia with age.

Source: The conversation

Why do we attract so much attention at festivals, anniversaries and other public events in large groups? According to the social brain hypothesis, it’s because the human brain has evolved specifically to support social interactions. Studies have shown that belonging to a group can lead to improved well-being and increased life satisfaction.

Unfortunately, many people are lonely or socially isolated. And if the human brain really evolved for social interaction, we should expect this to affect it significantly. Our current study, published in neurologyshows that social isolation is associated with changes in brain structure and cognition – the mental process of acquiring knowledge – and even carries an increased risk of dementia in older adults.

There is already a lot of evidence supporting the social brain hypothesis. One study mapped the brain regions associated with social interaction in about 7,000 people.

It showed that brain regions constantly involved in various social interactions are strongly connected 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 choose what we respect), 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. We therefore examined data from almost 500,000 people from the UK Biobank with an average age of 57 years. People were classified as socially isolated if they lived alone, socialized less than monthly, and participated in social activities less than weekly.

Our study also included neuroimaging (MRI) data from approximately 32,000 people. This showed that socially isolated people had poorer cognition, including memory and reaction time, 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 (involved in attention, planning, and complex cognitive tasks), and the hippocampus — a key area for learning and memory that is typically disrupted early on in Alzheimer’s disease.

We also found a link between the lower gray matter volumes and specific genetic processes involved in Alzheimer’s disease.

There were follow-ups with participants 12 years later. This showed that those who were socially isolated but not lonely had a 26% increased risk of dementia.

Underlying Processes

Social isolation needs to be examined more closely in future studies to determine the exact mechanisms behind its profound effects on our brain. But it’s clear that when you’re isolated, you can suffer from chronic stress. This, in turn, has a major impact on your brain and your physical health as well.

Another factor can 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 volume of the hippocampus increased as they memorized routes and addresses. For example, if we don’t regularly engage in social discussions, it’s possible that our use of language and other cognitive processes like attention and memory may decline.

This can affect our ability to do many complex cognitive tasks – memory and attention are critical to complex cognitive thinking in general.

combat loneliness

We know that a strong set of thinking skills called “cognitive reserve” can be built throughout life by keeping your brain active. A good way to do this is to learn new things, such as another language or a musical instrument.

Cognitive reserve has been shown to improve the course and severity of aging. For example, it can protect against a range of diseases or mental disorders, including forms of dementia, schizophrenia and depression, especially after traumatic brain injury.

People who are isolated from others do worse on cognitive tests. The image is in the public domain

There are also lifestyle elements that can improve your cognition and well-being, including a healthy diet and exercise. There are some pharmacological treatments for Alzheimer’s disease, but there is a need to improve their effectiveness and reduce side effects.

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There is hope that there will be better treatments for aging and dementia in the future. One way of investigating in this regard is exogenous ketones – an alternative source of energy to glucose – which can be obtained through dietary supplements.

But as our study shows, tackling social isolation could also help, especially in old age. Health authorities should do more to check who is in isolation and organize social activities to help them.

When people are unable to interact in person, technology can provide a substitute. However, this may be more true for younger generations who are more comfortable using technology to communicate. But with exercise, it can also be effective in reducing social isolation in older adults.

Social interaction is extremely important. One study found that the size of our social group is actually related to the volume of the orbitofrontal cortex (which is involved in social cognition and emotion).

But how many friends do we need? Researchers often refer to the “Dunbar number” to describe the size of social groups, noting that we are unable to maintain more than 150 relationships and typically only manage five close relationships.

However, there are some reports that suggest there is a lack of empirical evidence for Dunbar’s number, and that more research is needed on the optimal size of social groups.

It’s hard to argue that humans are social animals and enjoy connecting with others no matter what age we are. But, as we’re increasingly discovering, it’s also critical to the health of our cognition.

About this news from social isolation research

Authors: Barbara Jacquelyn Sahakian, Christelle Langley, Chun Shen and Jianfeng Feng
Source: The conversation
Contact: Barbara Jacquelyn Sahakian, Christelle Langley, Chun Shen and Jianfeng Feng – The Conversation
Picture: The image is in the public domain

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