Body composition, pre-diabetes and cardiovascular disease risk in early schizophrenia

Aim: This preliminary study examines the relationship between body composition, insulin resistance and NCEP-III-defined cardiovascular disease risk factors in persons early in the course of schizophrenia exposed to commonly prescribed atypical antipsychotic medications.

Methods: Subjects underwent modified oral glucose tolerance tests (OGTTs) and DEXA (dual X-ray absorptiometry) scans corrected for relevant sociodemographic data, including activity levels. We used linear multiple regression models to evaluate relationships between body composition and metabolic variables.

Results: Thirty-six individuals diagnosed with schizophrenia, receiving atypical antipsychotic monotherapy, and within 5 years of illness onset, participated. Average age was 25.1 ± 3.6 years (range, 19-34) and duration of illness was 2.5 years (30 ± 18 months). Mean body mass index (BMI) was 28.3 ± 4.9, with a mean total body fat mass of 28.6 ± 8.4%, suggesting an increase in fat relative to BMI. Ten participants (28%) had pre-diabetes (fasting glucose 100-126 mg dL^-1 or 2-h OGTT 140-200 mg dL^-1 ), but no participant had diabetes. Insulin resistance (HOMA-IR) was predicted by total body mass (BMI) more so than by body fat mass, with an incremental contribution derived from antipsychotics. Insulin secretion in response to glucose challenge was predicted by BMI, body fat mass and antipsychotic medication.

Conclusions: Fat mass relative to BMI was increased in early schizophrenia patients receiving atypical antipsychotics. Body composition accounted for most of the variance in risk for abnormalities in glucose metabolism. Incremental contributions were derived from atypical antipsychotics, in line with their known adipogenicity. If direct fat mass measures are unavailable, frequent BMI measures may be practical proxy markers for metabolic risk.