Hungry lonely brains

When hungry, not only our bodies long for food, our brains do too. And it appears that when it comes to social interaction, a similar thing happens. Social deprivation leads to a brain angry for social contact.

A recent study [Livia Tomova et al (2020) Acute social isolation evokes midbrain craving responses similar to hunger Nature Neuroscience doi: 10.1038/s41593-020-00742-z[/footnote] in Nature Neuroscience, led by neuroscientist Livia Tomova, showed that after a day of social deprivation, the brains of the participants lighted up when seeing pictures of people and human reunions, as much as they did looking at pictures of sugary foods when starving.

Forty participants spent 10 hours during one day without food, and at the end were shown pictures of chocolate cake or pizza. As hungry as they were, their brains, particularly, their substantia nigra pars compacta and ventral segmental area, were very excited to see those pictures.

Now, if you substitute lack of food for lack of human contact, the participants spent 10 hours in isolation –without access to social media, of course–, and afterwards when shown pictures of people just talking or spending time together, the same brain regions as when hungry also fired.

What is important to note is that the stronger the hunger or the social isolation experimented by the subjects, the higher the activation of these brains areas in the midbrain.

Interestingly, however, in those people who were generally lonelier, the responses were not as high. Although there is no clear explanation as to why, it might be that social isolation does not affect them that much because they’re sort of used to it.

Neurons in the midbrain, and specifically the substantia nigra pars compacta and ventral segmental area produce dopamine, which is the neurotransmitter associated with pleasure and addiction, among other functions, are also active when presented with food, drugs, social cues or any other reward-producing type of stimulus, because you don’t need to be hungry to eat, or feel lonely to seek a friend. But deprivation made them simply more active and more specific.

Now, if we focus on the global situation we’re experiencing due to COVID-19 with general lockdowns all around the globe, we might be facing a pandemic of social isolation of yet unknown psychological and physical consequences.