Patients with schizophrenia die up to 25 years earlier than the general population. This mental illness is associated with an altered perception of reality and severe distress. Treatment with antipsychotic medications can be helpful in reducing symptoms, but the majority of patients suffer from excessive weight gain as a side effect. In addition to making patients less self-confident and less likely to continue with their medication, the weight gain also puts patients’ health at an increased risk.

Dr Hisham Ziauddeen from the Department of Psychiatry and Dr Clemente Garcia-Rizo from the University of Barcelona led a study to find a predictor of this weight gain. Dr Ziauddeen said: “while weight gain on clozapine and other antipsychotic drugs is a very common side effect, thus far we have no way of knowing who is likely to experience this side effect and to what extent”. The team was particularly interested in birth weight as a predictor.

It has been shown that weight at birth is a good marker for the amount of stress experienced by a foetus. Stress can be caused by factors such as poor nutrition of the mother during pregnancy or an insufficient blood flow through the placenta. Individuals born after prolonged hunger periods in history often show lower birth weight. Dr Ziauddeen said:

“We have known for some time that adversities experienced during intrauterine life can result in a vulnerability to develop schizophrenia and metabolic disease later in life. Lower birth weight is a simple and good marker of such early life adversity”

The research team wanted to investigate this link between schizophrenia and metabolic disorders further. They used patient information from two databases from the Hospital Clinic Barcelona and the Cambridgeshire and Peterborough Foundation NHS Trust. Data on birth weight, current body mass index (BMI), and waist-to-hip ratio (WHR) were collected from three groups:

• 42 treatment resistant schizophrenia patients on the antipsychotic drug clozapine,
• 41 patients in their first episode of schizophrenia who were not receiving any antipsychotics,
• 72 healthy controls.

The analyses were controlled for age, gender, and duration of treatment, to account for these differences between the groups. Birth weight was indeed associated with higher BMI and WHR in the treatment resistant patients, but not in the first episode of psychosis patients or the healthy volunteers. The data suggest that a lower birth weight can serve as a predictor of weight gain induced by antipsychotics.

Dr Emilio Fernandez-Egea, senior author of the study, said about future directions:

“Given that birth weight is an extremely simple measure and one that can be obtained from health records, if we can demonstrate its value convincingly, it would be extremely helpful to both patients and clinicians in determining what an individual’s risk of gaining weight on their treatment is. For this reason we are currently looking to see if we can replicate this finding in other populations and look at the impact of birth weight on other metabolic measures in these patients”.

Written by Julia Gottwald