What does loneliness look like in the brain?


BRAIN images from people experiencing loneliness show distinct features within certain neural regions, suggesting that those who feel lonely may be able to fill their desire for human connection by imagining social contexts and interactions.
Human connection is a key factor in people’s physical and mental health. However, the impacts of Covid-19 and the need for physical distancing are making it challenging to avoid feelings of isolation.
A new study by researchers from the Montreal Neurological Institute-Hospital in Canada, the results of which now appear in the journal Nature Communications, suggests that the brains of people who experience loneliness display specific patterns in a network of regions called the default network.
This network is associated with thinking processes, including the abilities to remember, imagine, and plan for different moments in time.
Participants for this study were around 40,000 individuals from the UK Biobank imaging-genetics cohort, which is an open access biomedical database. The researchers collected initial data for their study through a self-assessment questionnaire on loneliness, along with genetic and lifestyle factors.
The study paper notes that the measure of loneliness was not necessarily dependent on the amount of social contact that each person had. Instead, the team focused on self-perceived loneliness.
In addition to the self-assessment, the researchers also acquired MRI brain scans from the UK Biobank to examine brain characteristics of gray matter, white matter, and functional connectivity.
Gray matter refers to brain regions consisting of neuronal cell bodies involved in processing information, while white matter consists of axons and is involved in transmitting signals. Functional connectivity signifies the communication of signals across brain regions.
For the three examined characteristics, the researchers found that the brains of individuals who felt socially isolated exhibited distinct patterns that were not present in non-isolated individuals. Furthermore, these patterns were central to the area of the default network. In lonely people, this network contained more gray matter. It also displayed greater stability of the fornix, which is a bundle of white matter in the hippocampus that sends signals to the default network.
Also, the network had stronger connections across brain regions. These patterns indicate that the brain is able to express a unique signature with features that can distinguish a “lonely brain” from a non-lonely one.