Loneliness: A disease that changes brain structure and function

Loneliness increases the risk of poor sleep, higher blood pressure, cognitive and immune decline, depression, and ultimately an earlier death. Why? The traditional explanation is that lonely people lack life’s advisors: people who encourage healthy behaviours and curb unhealthy ones. It is believed that ignorance is the true disease, loneliness just a symptom.

But this can’t be the full story. Introverts with small networks aren’t at especial health risk, and people with an objectively full social life can feel lonely and suffer the consequences. A new review argues that for the 800,000 UK citizens who experience it all or most of the time, loneliness itself is the disease: it directly alters our perception, our thoughts, and the very structure and chemistry of our brains.

The review suggests lonely people are sensitive to negative social outcomes and accordingly their responses in social settings are dampened. Functional imaging evidence also shows lonely people have a suppressed neural response to rewarding social stimuli, which reduces their excitement about possible social contact; they also have dampened activity in brain areas involved in predicting what others are thinking – possibly a defence mechanism based on the idea that it’s better not to know. All this adds up to what the authors characterise as a social "self-preservation mode.

Other basic brain processes are also upset by isolation. Isolated mice show reduced delta-wave activity during deep sleep; and their inflammatory responses also change, meaning that in one study, three in five isolated mice died following an induced stroke, whereas every one of their cage-sharing peers survived the same process.

The research is clear that loneliness directly impacts health.

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Source material from British Psychological Society