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The past few decades have seen the development of clinical and pathological diagnostic criteria for behavioural variant-frontotemporal dementia (bvFTD).1 ,2 Despite these advances, a small number of patients remain difficult to classify. These patients are almost exclusively male and are termed phenocopy cases. They show behavioural changes, and may exhibit mild frontal dysexecutive cognitive deficits identical to patients with bvFTD. In contrast to bvFTD, progression is often very slow and indolent spanning decades, and the typical frontal and temporal abnormalities on neuroimaging are lacking. Despite recognition of the phenocopy syndrome the underlying pathology has not yet been reported. We report the clinical and pathological findings in two phenocopy cases.
A 62-year-old retired man was referred to the memory clinic in 1992 with a 4-year history of insidious behavioural changes. Problems were first apparent when he became withdrawn and agitated following a number of minor car accidents. Despite treatment for depression his behaviour deteriorated and over the ensuing few years he was disinhibited in social situations, threatened his neighbours, and began to secretly consume alcohol. He showed reduced empathy towards his wife and family. In stark contrast to his wife's reports, the patient had no insight into these problems.
His medical history was unremarkable. Similarly, there was no significant family history of neurodegenerative or psychiatric illness.
On the Addenbrooke's cognitive examination-revised (ACE-R) he scored 90/100 (normal >88/100). More detailed neuropsychological examination showed mild impairment of executive tasks. In …