Effect of diagnostic criteria on prevalence of frontotemporal dementia in the elderly

Background Frontotemporal dementia (FTD) is believed to be rare in the elderly, and the influence of different criteria on the prevalence of FTD is unclear. Methods Population-based samples of 70- to 95-year-olds (n = 2462) in Gothenburg, Sweden, underwent neuropsychiatric examinations. Behavioral variant FTD (bvFTD) was diagnosed according to the International Behavioural Variant FTD Criteria Consortium (FTDC), the Frontotemporal Lobe Degeneration Consensus criteria, and the Lund-Manchester Research Criteria. A subset (n = 1074) underwent computerized tomography (CT) of the brain. Results The prevalence of bvFTD varied between 0.2% and 0.5% at age 70 to 79 years, between 2.5% and 3.6% at age 80 to 89 years, and between 1.7% and 2.2% at age 90 to 95 years. The agreement between different criteria was low to moderate (κ = 0.20-0.42). Among those with bvFTD according to FTDC, 93.3% had frontal and/or temporal lobar atrophy on CT, compared with 12.6% of those without bvFTD (P <.001). Conclusions The prevalence of bvFTD was higher than expected in this population. To a large extent, different criteria captured different individuals.