Bone mineral density in patients with psychosis and non-psychotic siblings

Background: Increased rates of altered bone mineral density (BMD), like osteopenia and osteoporosis, have been reported in schizoprenia, but the underlying mechanism are not yet fully elucidated. Reduced BMD, as a biological marker of diminished cumulative estrogen exposure, has been suggested to be a marker of increased psychosis risk. In the present family study we tested whether decreased BMD is also an indicator of genetic liability for the disorder. Methods: As part of an observational longitudinal study, BMD of the spine and femur was measured with dual-energy-X-ray absorptiometry (DXA) in a subsample of 42 patients with schizophrenia,54 non-psychotic siblings of these patients and 39 controls. Preliminary, multilevel random regression, analyses were performed to assess group differences in bone mineral density of the lumbar spine and femur (baseline measures). Results: In female patients, bone mineral density was significantly lower than in controls, in those not using contraceptives. This effect was found in both the lumbar spine (b = 0.74, P < .024) and femur (b =0.66, P < .05). Female siblings also showed (trends of) decreased bone mineral density in the lumbar spine and femur region compared to controls. In male patients and siblings, bone mineral density was not significantly altered compared to controls. Conclusions: Both female patients and their non-psychotic female siblings may have decreased bone mineral density. This data support not only that reduced BMD, as a biological marker of diminished cumulative estrogen exposure, may be a marker of increased psychosis risk, but also that reduced BMD may be a marker of the genetic liability for schizophrenia