Abstract
Background: It is known that patients with Early Onset Dementia (EOD), defined as dementia with symptoms onset before the age of 65, frequently present with atypical clinical syndromes. However, the epidemiology of the different presentations of EOD, including the clinical variants of Alzheimer’s dementia (AD) and frontotemporal dementia (FTD), has never been investigated altogether in the same population-based study, probably because their characterisation is relatively recent, and subsequent to the advent of AD biomarkers. Epidemiologic data on all-causes of EOD are also scarce, inconsistent, and mostly based on low-level clinical assessment.
Method: We investigated the epidemiology of EOD in the province of Modena, Northern Italy (700,000 inhabitants), by identifying newly-diagnosed EOD patients retrospectively from January 2006 to December 2016, and prospectively from January 2017 to June 2019. Diagnosis was based on extended clinical and neuropsychological assessment, and supported by the use of imaging and cerebrospinal fluid biomarkers in the majority of cases.
Result: EOD age- and sex-adjusted incidence was 6.45/100000 inhabitants/year during the 2016-2019 period, corresponding to 46 new cases per year in the overall study population. At census day (30th June 2019), there were 258 patients with a clinical diagnosis of EOD (123 males) in the province of Modena. Crude Prevalence was 74.3/100000 (71.2 in males and 77.4 in females) in the population aged 30-64, and 119.9/100000 (117.1 in males and 122.6 in females) in the population aged 45-64. Overall crude prevalence was 36.4/100000 inhabitants (35.5/100000 in males, 37.4/100000 in females). The most frequent EOD was the amnestic variant of AD (crude incidence of 21.6/100000 and prevalence of 5/100000 persons aged 30-64 years), followed by the behavioural variant of FTD (crude incidence of 14.1/100000 and prevalence of 2.8/100000 persons aged 30-64 years), and logopenic variant of primary progressive aphasia (crude incidence of 5.8/100000 and prevalence of 0.8/100000 persons aged 30-64 years).
Conclusion: We provide the first report on incidence and prevalence of all the clinical presentations of EOD including different variants of AD and FTD. These epidemiological data will benefit the clinical reasoning of clinicians faced with dementia in young patients and will allow to improve dementia care organisation.