[Behavioural changes as a symptom: diagnosing behavioural variant frontotemporal dementia].

Behavioural variant frontotemporal dementia (bvFTD) is a neurodegenerative disease, the symptoms of which are changes in character, behavioural changes and socio-cognitive changes occurring predominantly at an age between 40 and 70 years. Frontotemporal atrophy is apparent on diagnostic imaging in 70% of patients with bvFTD; a diagnostic dilemma arises if this is not clearly obvious. Validated questionnaires for stereotypical behaviour, depressive symptoms and apathy, and neuropsychological examination can be very helpful in differentiating between bvFTD and psychiatric and other neurological conditions. A brain MRI is always indicated in patients displaying behavioural changes; frontal or temporal atrophy on brain MRI provide sufficient support for the diagnosis 'probable bvFTD'. When in doubt, a supplementary 18F-FDG-PET scan can be performed, but hypometabolism on an 18F-FDG-PET scan can give a false-positive result. If bvFTD is suspected, a multidisciplinary approach, clinical follow-up for 2 years and referral to an FTD centre of excellence are recommended. Conflict of interest and financial support: none declared.