Late onset bipolar disorder associated with white matter hyperintensities: a pathophysiological hypothesis.

Vascular depression is, nowadays, a well-established concept in the literature. However, the possible emergence of late onset bipolar disorder in subjects with no antecedents of mood disorder or after a chronic or recurrent course of unipolar depression constitutes a poorly studied issue, despite its importance in clinical practice. Here, we present the case of a 72-year-old female patient who began to present recurrent major depressive symptoms, resistant to pharmacological treatment, from the age of 58. Three years later, she started to present phases of mania with rapid cycling features. A brain MRI scan showed prominent white matter hyperintensities (WMH). WMH are frequently found in the elderly population, but with greater burden in individuals with hypertension and cerebrovascular disease. WMH impair cortical function and damage the cerebral tissue. WMH have been associated with adult-onset bipolar disorder and late onset depression, and are linked to a worse prognosis of both conditions. The present case report highlights the possibility that vascular-related WMH may provoke late onset bipolar disorder by damaging frontolimbic circuits implicated in the pathophysiology of mania.