Loneliness changes the brain
Loneliness not only impairs a person's quality of life, but also affects his or her health. Studies have shown that this condition is associated, for example, with an increased risk of cardiovascular and neurological diseases and reduces life expectancy. "Hitek" tells us how loneliness affects the brain and what can be done about it.Human evolution is largely determined by selection based on interpersonal interactions. Social interactions have been a necessary condition for survival for thousands of years. Anthropologists call humans "ultrasocial animals," emphasizing the extreme dependence of our species on each other.
Not surprisingly, a lack of sufficient social activity can lead to significant physical and psychological problems. A key problem is the experience of "loneliness. At the same time, researchers distinguish between the concepts of social isolation (objective loneliness) and subjective dissatisfaction with social connections (subjective loneliness). A person may have few social contacts, but at the same time he or she may not feel lonely, and vice versa.
Subjective loneliness is the emotional stress that people experience when their innate need for intimacy and companionship remains unsatisfied, when real-life relationships do not meet expectations. And while there is hardly a person who doesn't have to deal with this feeling at one point or another when loneliness becomes chronic or severe, the long-term effects can be very damaging to health.
In a 2020 study, neurobiologists from MIT and the Salk Institute for Biological Research studied how neural responses change when there is a lack of food and social interactions. The results showed that loneliness induces neural responses in the brain similar to those that correspond to feelings of hunger.
During the experiment, 40 participants were starved for 10 hours or subjected to complete social isolation. In the second part of the study, participants were locked in a room, not allowed to use phones, and only a computer was left in the room for emergency communication with the researchers.
After completing each phase, the researchers gave each participant a functional magnetic resonance imaging (fMRI) scan to measure brain activity and compared it with the participants' original fMRI scans. To avoid social contact, participants made their own way to the machine and did not see or interact with the researchers until the end of the scan.
The analysis showed that midbrain areas associated with hunger and drug cravings were also activated in the case of social isolation. In this case, after complete isolation, the sight of people having fun together activated the same brain area that "lights up" when a hungry person sees the image of a plate of pasta.
"People who are forced into isolation crave social interactions the same way a hungry person craves food. Our finding is consistent with the intuitive notion that positive social interaction is a basic human need, and that acute loneliness is an aversive state that prompts people to regain what they lack, similar to hunger," Rebecca Sachs, professor at MIT and study co-author.
Does loneliness shrink the brain?
Not only social interactions, but also cognitive abilities and even brain size suffer from loneliness. In 2019, a team of German scientists presented the results of observations of nine participants on a polar expedition to Antarctica. They all spent about 14 months on the southernmost continent.The eight expedition members, who worked at the Neumayer III station, agreed to undergo brain scans before and after their mission and to monitor brain chemistry and cognitive function during their stay. A ninth crew member also participated in the study, but was unable to undergo a brain scan for medical reasons.
The analysis showed that, compared to the control data, the participants had decreased prefrontal cortex volume over the course of the experiment. This is the area that is responsible for decision-making and problem solving. At the same time, the volume of the dentate gyrus decreased by an average of 7%. They also had decreased levels of BDNF, a brain-derived neurotrophic factor responsible for neuronal growth and development.
The sample of this study is limited and it is unclear how much of these changes were due to social isolation and how much was determined by other factors (e.g., the harsh environment of the Antarctic station). But the results are indirectly consistent with other observations.
For example, in a study of more than 11,000 people, researchers found that those who reported high levels of social loneliness had above-average cognitive and memory decline. And another study found that older lonely people often have atrophy in parts of the brain, including the thalamus, which processes emotions, and the hippocampus, the memory center.
Sources: Effects of Objective and Perceived Social Isolation on Cardiovascular and Brain Health: A Scientific Statement From the American Heart Association | Journal of the American Heart Association (ahajournals.org), Acute social isolation evokes midbrain craving responses similar to hunger | Nature Neuroscience