Why are we excited to be in large groups at festivals, jubilees and other public events? According to the social brain hypothesis, it’s because the human brain evolved specifically to support social interactions. Studies have shown that belonging to a group can improve well-being and increase life satisfaction.
Unfortunately, many people feel lonely or socially isolated. And if the human brain really did evolve for social interaction, we should expect this to significantly affect it. Our recent study, published in Neurology, shows that social isolation is linked to 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 much evidence in support of the social brain hypothesis. One study mapped brain regions associated with social interaction in approximately 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 focused on the outside world), the salience network (which helps us to select what we want). paying attention), 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, consisting of neurons. Therefore, we investigated data from almost 500,000 people from the UK Biobank, with a mean age of 57 years. People were classified as socially isolated if they lived alone, had social contact less than once a month, and participated in social activities for less than a week.
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 a lower volume of gray matter in many parts of the brain. These areas included the temporal region (which processes sounds 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 interrupted early. in Alzheimer’s disease.
We also found a link between lower gray matter volumes and specific genetic processes that are 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 in more detail 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 huge impact on your brain and physical health as well.
Another factor may be that if we don’t use certain areas of the brain, we lose some of their function. A study with taxi drivers showed that the more they memorized routes and addresses, the more the volume of the hippocampus increased. 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.
This can affect our ability to perform many complex cognitive tasks: memory and attention are crucial for complex cognitive thinking in general.
We know that a strong set of thinking skills, called “cognitive reserve,” can be developed throughout life by keeping the brain active. A good way to do this is by learning 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 can protect against a number of mental health illnesses or disorders, including forms of dementia, schizophrenia, and depression, especially after traumatic brain injury.
There are also lifestyle elements that can improve your cognition and well-being, including a healthy diet and exercise. For Alzheimer’s disease, there are some drug treatments, but their effectiveness needs to be improved and side effects reduced. There is hope that in the future there will be better treatments for aging and dementia. One avenue of research in this regard is exogenous ketones, an alternative energy source to glucose, which can be ingested through nutritional supplements.
But as our study shows, addressing social isolation could also help, particularly in old age. Health authorities should do more to control who is isolated 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 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 adults.
Social interaction is very important. One study found that the size of our social group is actually associated with the volume of the orbitofrontal cortex (involved in social cognition and emotion).
But how many friends do we need? Researchers often refer to “Dunbar’s number” to describe the size of social groups and find that we can’t maintain more than 150 relationships, and usually only manage five close relationships. However, there are some reports suggesting a lack of empirical evidence around Dunbar’s number and more research on the optimal size of social groups is required.
It’s hard to argue with the fact that humans are social animals and enjoy connecting with others, no matter how old we are. But, as we are discovering more and more, it is also crucial for the health of our cognition.