Motivation Drain

When a person feels ill, their mental and physical motivation can often diminish. Short term, such feelings may be beneficial, promoting rest and recuperation. But, with chronic illnesses, the reduced motivation may develop into severe apathy and depression – an extreme version of this being seen in cancer patients with cachexia (wasting syndrome). Recently, scientists have identified the brain circuitry behind this illness-induced motivation slump. Using a mouse model of cachexia, they showed that the neurons (green) of a brain region called the area postrema (pictured) were responsive to interleukin 6 – an inflammatory cytokine (type of small protein) found at unusually high levels in cachexia. In turn, these neurons inhibited the release of the feel-good factor dopamine in a key part of the brain’s reward system – thus sapping the animals’ drive. Importantly, blocking this inflammation-neuronal circuitry, restored motivation in the cachectic mice, providing hope that such a strategy might benefit cancer patients too.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image by Aelita Zhu, Washington University in St. Louis - from work by Xiaoyue Aelita Zhu (朱晓悦) & Sarah Starosta et al
• Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, USA
• Image copyright held by Washington University in St. Louis
• Research published in Science, April 2025