The role of white matter damage in late onset bipolar disorder.

Bipolar disorder in elderly is probably heterogenous and the age of onset has been considered to be a potential clinical marker of heterogeneity for this disease. Early- and late-onset bipolar disorders share symptoms, but it is not clear whether they have different aetiologies and vulnerabilities. In bipolar disorder one of the most frequent neuroimaging finding is the white matter hyperintensities (WMHs). The disruption caused by WMHs in the connectivity between structures related to mood regulation and cognition in elderly may be responsible for the affective symptomatology seen in these patients. White matter hyperintensities are found both in late onset patients and in early age onset bipolar patients. It is likely that the aetiology of the white matter hyperintensities in late-onset bipolar disorder be multifactorial, although cardiovascular changes in particular seem to contribute to their physiopathology. In early life onset the aetiology of these lesions is less clear, although probably genetic factors are more important than cardiovascular factors. Understanding the aetiopathogenesis is of key importance when dealing with this disease.