Social isolation can impair cognition and increase the risk of dementia in older adults

⇧ [VIDÉO] You may also like this partner content (after viewing)

Much more complex than loneliness, with which it is often confused, social isolation can affect mental health and become both a cause and a symptom of mental disorders. Previous research has shown that a sense of belonging to a group can improve overall well-being and increase happiness. However, the neurobiological mechanisms underlying the phenomenon of social isolation or vice versa (belonging to a group) are still poorly understood. A new study offers a new clue by highlighting changes in the structure of the brain in people suffering from social isolation. These changes would be found mainly at the level of areas responsible for cognition and would lead to an increased risk of dementia..

The containment measures taken to combat the COVID-19 pandemic have exacerbated the phenomenon of social isolation and loneliness. Namely that they are two completely different terms, because one is characterized by the lack of social interactions, while the other is more likely to be translated as an emotion. For example, we can still feel alone when we are surrounded, for example when we prefer the company or attention of a certain person.

People affected by social isolation have little or no contact with others. In some cases, social isolation can also be associated with loneliness. Also, the quality of the relationships would be more important than the quantity. Therefore, belonging to very large groups cannot replace interacting with a small group of close friends.

Older people are the most affected by social isolation, as they often live alone or gradually lose their friends. However, it should be noted that the phenomenon is likely to affect almost everyone, for example, after emotional shocks. In France, for example, it would affect almost 14% of the population in 2020, compared to 9% in 2010.

Social isolation affects mental health because the human brain would be better equipped to function and develop in society, a group behavior inherited from primates. The so-called “social” brain would have evolved to acquire specific neural networks for the management of interactions, such as recognizing the other as a conversational partner, processing the information exchanged, managing them emotionally and choosing appropriate responses.

These neural areas would be closely associated with those that control cognition (the process of acquiring knowledge), including the standard neural network (active when not facing the outside world), the salience network (which selects the object of attention), the subcortical network (involved in memory, emotion and motivation) and the central executive network (which regulates emotions).

The new study, co-led by the University of Cambridge, delved deeper into the neural mechanisms that link social isolation to cognitive impairment. The results presented in the National Library of Medicine support previous hypotheses and show significant changes in gray matter levels in socially isolated individuals. These changes would increase the risk of dementia in older people.

Loss of gray matter volume

The new study analyzed UK Biobank data from an average of 462,619 people aged 57 years. These people lived alone, had social interactions less than once a month, and participated in social activities less than once a week. These individuals were classified as socially isolated. The study also analyzed the MRIs of 32,263 other people with an average age of 63 years.

The results showed that people suffering from social isolation had lower cognitive abilities (memory and reaction time) as well as lower gray matter volume in several key areas of the brain. These volume losses were particularly localized in the temporal zone (which encodes memory), the frontal lobe (involved in attention, planning, and complex cognitive tasks), and the hippocampus (involved in learning and memory).

12 years later, people experiencing social isolation (but not loneliness) had a 26% greater risk of dementia. In addition, the decrease in gray matter volume was associated with a decrease in the activation of certain genes that prevent the symptoms of Alzheimer’s disease.

However, researchers still need to consider many factors and obtain a larger study sample. For example, the psychological and physical effects caused by social isolation can be correlated with the stress generated. In addition, the affected parts of the brain could lose volume, likely from lack of demand, like a muscle atrophied by immobility.

Source: National Library of Medicine

Leave a Comment