Loneliness can influence the brain and promote alcohol consumption, according to a new study led by Northwestern University and the Salk Institute for Biological Studies (both in the United States). The researchers of this work, published in Nature Neuroscience, have identified for the first time th…
Loneliness can influence the brain and promote alcohol consumption, according to a new study led by Northwestern University and the Salk Institute for Biological Studies (both in the United States). The researchers of this work, published in Nature Neuroscience, have identified for the first time the brain mechanism that boosts consumption of this substance in male mice, and which, at the same time, reduces it in females. Currently, loneliness has increased worldwide, a fact recognized as an important risk to public health with strong links to substance abuse. Previously, experts had already warned that social isolation had become an 'epidemic', but until now scientists did not fully understand how 'reconfigures' the brain to increase vulnerability to alcoholism. "This is the first work that identifies a specific brain circuit that explains how social isolation can cause an increase in alcohol consumption in men, which represents a great advance for this field", said the lead author of the study and researcher at Northwestern University, Reesha Patel. "These findings provide a much clearer biological target to understand and, ultimately, treat substance abuse derived from loneliness, a problem that is becoming increasingly common". Gender differences During the investigation, some adult mice, regardless of gender, were divided into groups to be transferred to individual cages and simulate loneliness in adulthood. The rest remained in groups as control specimens. All of them were offered the opportunity, during one hour a day, to drink from a water bottle or from a bottle filled with a 15% alcohol solution. The researchers monitored their consumption and choices for two weeks, a period in which males progressively increased their alcohol consumption, while females reduced it. With miniature microscopes, scientists recorded the activity of specific brain cells while the animals moved freely and decided whether to drink alcohol or not. The cells analyzed formed a brain pathway that connected the basolateral amygdala —which processes emotional and stress signals— with the medial prefrontal cortex, which regulates decision-making. "Our work shows that a specific pathway becomes hyperactive during loneliness and directly increases alcohol consumption", Patel says. However, "males and females resort to different neuronal strategies when they feel lonely, a phenomenon that could help us explain the gender differences observed in neuropsychiatric disorders". The researchers point out that they cannot be certain why isolation increased consumption in some and reduced it in others, although Patel noted that the gender differences observed in the study reflect patterns described in some research with human beings. Activate and deactivate the 'circuit' On the other hand, the team checked if this brain pathway was limited to reflecting alcohol consumption or causing it. Through optogenetics —brief pulses of light—, they artificially activated the circuit in non-isolated male mice. This caused their brains to respond to alcohol as if they had been separated.
On the contrary, when these same circuits were silenced in male mice that were alone, alcohol consumption decreased. Next steps
After their research, the experts seek to understand what maintains this hyperactive system during social isolation and how the brain regions located lower down in the chain, including the medial prefrontal cortex, contribute to this effect. In addition, they plan to investigate why males and females respond so differently to isolation and if hormones or other deeper differences play a role. Another important step will be to identify how these findings can be extrapolated to humans. Reference: Reesha. P. et al. Social isolation recruits amygdala–medial prefrontal cortex projections to escalate alcohol drinking in male mice. Nature Neuroscience. 2026. Source: SINC
