2 Neuroscience2.8 Modulators, hormones and inflammatory responses
2.8.6 Metabolism and psychiatric treatment
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Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
How mental illness and metabolism are linked
The link runs both ways. Obesity and psychiatric illness can share behavioural, social and biological influences. Their association does not mean one causal pathway applies to everyone.
Appetite control. Circuits in the hypothalamus combine energy signals, such as leptin and insulin, with information about available nutrients. Reward circuits shape how motivating food feels.
Insulin resistance and inflammation. Both can come with obesity, including inflammation in fat tissue. Inflammatory markers in the blood are not specific, so they cannot diagnose a psychiatric illness.
Other contributors. Poor sleep, poverty, food access and low physical activity can add to medication effects and inherited susceptibility.
How treatment affects metabolism
Mechanism | Possible consequence |
|---|---|
Blocking histamine H1 and serotonin 5-HT2C receptors | Increased appetite with some antipsychotics |
Sedation | Less activity and changed eating routines |
Changes in insulin regulation | Abnormal blood glucose (dysglycaemia) that may not track weight change exactly |
More body fat and abnormal blood lipids (dyslipidaemia) | Higher longer-term cardiometabolic risk |
Clozapine and olanzapine carry a substantial metabolic risk. Individual responses vary, and the drug's clinical benefit still counts in treatment decisions.
Animal studies help explain plausible pathways, such as appetite signalling in the hypothalamus. They do not prove that one receptor accounts for all weight gain in people.
Monitoring and physical health
Weight alone misses other harms. Also check waist circumference, blood pressure, glycaemic measures and lipids.
Measure at baseline and repeat during treatment. This separates problems that were already there from changes on treatment, and lets you act in good time.
Physical healthcare is part of psychiatric treatment. Metabolic disease can affect function, medication choices and mortality.