Red herrings in the diagnosis of frontotemporal dementia: A case of probable bipolar disorder evolving into frontotemporal dementia

Bipolar illness and Frontotemporal dementia (FTD) share many common features. The clinical features of mania such as excessive cheerfulness, hyper-sexuality and overspending can mimic impaired judgement and loss of inhibition seen in FTD. The depressive features such as anhedonia, decreased social interaction can mimic apathy associated with FTD. Among the FTD subtypes the behavioural variant of FTD (bv-FTD) can mimic a bipolar disorder, especially when it occurs in late life. Initially, patients with behavioural variant of FTD generally have behavioural changes with relatively preserved memory thus presenting a diagnostic challenge. The literature on bipolar disorder converting or progressing to FTD is limited to case reports and case series. In this case report we describe about an elderly gentleman with prior bipolar illness who later evolved into FTD. The diagnostic as well as management challenges have been discussed.