Heterozygous β-thalassaemia as a susceptibility factor in mood disorders: excessive prevalence in bipolar patients

Alberto Bocchetta

Bernard B. Brodie Department of Neurosciences, University of Cagliari, Italy

author email corresponding author email

Clinical Practice and Epidemiology in Mental Health 2005, 1:6doi:10.1186/1745-0179-1-6


Published:	1 June 2005

Abstract

Background

Previous preliminary reports have suggested potential interactions between microcytic anaemia and mood disorders. In particular, heterozygous β-thalassaemia has been implicated in the bipolar spectrum. This study surveyed relevant haematological parameters in a large sample of psychiatric outpatients with the aim of clarifying previous observations.

Methods

Mean Corpuscular Volume (MCV) was analysed in 1014 consecutive patients diagnosed according to modified Research Diagnostic Criteria (RDC). Haemoglobin electrophoresis and/or chromatography was performed in blood samples from 143 patients with reduced MCV. Prevalence of heterozygous β-thalassaemia was estimated based on the rates of patients with reduced MCV and increased haemoglobin A₂concentration.

Results

MCV lower than 80 μ³was found in greater proportions among bipolar compared with the remaining RDC subgroups (183/732 = 25.0% versus 51/282 = 18.1%; p = 0.02; relative risk = 1.38; Fisher's exact test). This difference can mainly be attributed to heterozygous β-thalassaemia, the estimated prevalence of which was 16.4% among bipolar and 9.9% among non-bipolar subgroups (p = 0.01; relative risk = 1.65).

Conclusion

The results are consistent with the hypothesis that heterozygous β-thalassaemia might play a role as a susceptibility factor in bipolar spectrum disorders in specific populations.