Background:
Previous studies have suggested that there may be bipolar disorder subtypes according to age at onset (AAO), including a late-onset (LO) group with onset in the fifth decade of life. LO presentations may be associated with greater cerebrovascular disease and increased neuropsychological deficits. Different AAO may also explain some of the genetic heterogeneity associated with bipolar disorder.
Method:
We have commenced recruitment of participants aged 40 years and over, with the aim of assessing early-onset bipolar I, late-onset bipolar I and healthy control groups. Assessment tools included the following: sociodemographic and disability questionnaires, SCID, HDRS, YMRS; cerebral magnetic resonance imaging scan; a neuropsychological battery and venepuncture for genetic testing.
Results:
Preliminary results for the first 15 participants with bipolar disorder (mean age 53.9 years, range 46-66 years, 66% women) have shown an average latency of 11 years between the first affective episode and the first episode of mania, and of 17 years before a formal diagnosis of bipolar disorder. There was a high rate of comorbidity with anxiety disorders. Contrary to study hypotheses, the participants tended to be relatively physically healthy with minimal vascular disease burden. Neuropsycho-logical assessment of euthymic participants showed no differences in language and memory, but significant differences in visuospatial organization and self-monitoring tasks.
Conclusions:
These preliminary results suggest deficits in frontal executive dysfunction in this sample of older bipolar participants. The recruitment of a relatively young and ambulatory sample may have led to the finding of minimal vascular disease.
