[Differences among dementias according to onset age: study based on dementia registry data]

To know cognitive, functional and sociodemographical features as risk factors in order to differentiate dementias based on onset age of illness.

Cross-sectional and analytical study based on 670 cases of a pilot program for dementia from the Gerona Hospital Registry for dementias. The cases were standardized and registered consecutively during the 2004-2005 biennium.

A total of 10.3% (n=69) of patients who were included in the registry showed the first symptoms of dementia before they were 66 years old. The distribution of the dementia diagnoses differed according to age at onset of illness, with greater frequency of frontotemporal dementia in the early-onset dementia group. Patients with early-onset dementia showed less functional and cognitive impairment than patients with late-onset dementia. They also had more behavioral and psychological disorders than the late onset cases as well as a greater number of family backgrounds of Down's syndrome and personal background of depression. No vascular risk factors differences between late-and-early-onset dementias were found.

Early-onset dementias showed different clinical manifestations, risk factors and diagnostic distributions versus the later onset ones. The registry program for dementia is a useful tool to study low prevalence characteristics of diseases leading to the dementia condition.