Prolonged loneliness can transform the brain to make you MORE antisocial
Changes in the brain’s white matter have been seen before in psychiatric disorders, and demyelinating disorders like multiple sclerosis have also had an association with depression. Recently, myelin changes were also seen in very young animals or adolescents responding to environmental changes. But Karen Dietz, lead author on the study published online in the journal Nature Neuroscience, said: ‘This research reveals for the first time a role for myelin in adult psychiatric disorders.
‘It demonstrates that plasticity in the brain is not restricted to neurons, but actively occurs in glial cells, such as the oligodendrocytes, which produce myelin.’
Myelin is a crucial fatty material that wraps the axons of neurons, helping them signal effectively. Normal nerve function is lost in demyelinating disorders, such as MS and the rare, fatal childhood disease, Krabbe’s disease.
The paper revealed how the stress of social isolation disrupts the sequence in which the myelin-making cells, the oligodendrocytes, are formed.
In an experiment, adult mice – normally social animals – were isolated for eight weeks to induce a depressive-like state, before being introduced to a mouse they hadn’t met before.
While mice are normally highly motivated to be social, those who had been socially isolated did not show any interest in interacting with the new mouse, a typical model of social avoidance and withdrawal.
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Brain tissue analysis of the isolated animals revealed significantly lower than normal levels of gene transcription for oligodendrocyte cells in the prefrontal cortex, a brain region responsible for emotional and cognitive behavior.
‘This research provides the first explanation of the mechanism behind how this brain plasticity occurs showing how this change in the level of social interaction of the adult animal resulted in changes in oligodendrocytes,’ said Dr Dietz, a research scientist in the Department of Pharmacology and Toxicology in the UB School of Medicine and Biomedical Sciences.
The key change was that cellular nuclei in the prefrontal cortex contained less heterochromatin, a tightly packed form of DNA material, which is unavailable for gene expression.
‘This process of DNA compaction is what signifies that the oligodendrocytes have matured, allowing them to produce normal amounts of myelin,’ Dr Dietz said. ‘We have observed in socially isolated animals that there isn’t as much compaction, and the oligodendrocytes look more immature.
‘As adults age, normally, you would see more compaction, but when social isolation interferes, there’s less compaction and therefore, less myelin being made.’
She added, however, that the research also showed that myelin production went back to normal after a period of social integration, suggesting that environmental intervention was sufficient to reverse the negative consequences of adult social isolation.
Dr Dietz said the findings have implications for future questions regarding MS and other myelin disorders.
‘This research suggests that maybe recovery from an MS episode might be enhanced by social interaction,’ she says. ‘This opens another avenue of investigation of how mood and myelin disorders may interact with one another.’
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