White matter lesions and season of birth of patients with bipolar affective disorder

Objective: it is established that patients with bipolar disorder have an ex cess of births in winter or early spring, The authors investigated a link b etween season of birth and white matter lesions with magnetic resonance ima ging (MRI). Method: T-2-weighted and proton density MRI scans were examined for 79 pati ents with bipolar disorder (DSM-IV) for the presence of deep subcortical an d periventricular white matter lesions. The birth seasons of patients with white matter lesions were compared with those of the general population. Results: Thirteen subjects exhibited deep subcortical white matter lesions, of whom nine (69.2%) were born in the winter months (January to March). Se ven of these patients remained symptomatic, despite adequate treatment for more than 2 yea rs. Conclusions: Birth season, illness outcome, and deep subcortical white matt er lesions appear to be closely linked. Deep subcortical white matter lesio ns may be a marker of a toxic or infective insult in utero.