Abstract
Objective: As the literature on conventional criteria for discriminating early-onset (EO) from late-onset (LO) Alzheimer’s disease (AD) is sparse and controversial, the aim of this study was to establish a precise age at onset (AAO) criterion, by using a specific statistical procedure, and to describe the clinical characteristics of the two sub-groups. Methods: Admixture analysis was performed to establish the AAO cut-off in a multi-center study including 2000 AD patients consecutively recruited in eight Italian Memory Clinics. None of the patients were taking acetylcholinesterase inhibitors, antipsychoticor anti-depressant drugs. At the first diagnosticvisit, they were administered the Mini Mental StateExamination, the Basic and Instrumental Activities of Daily Living and the Neuropsychiatric Inventorytoassess clinical phenomenology. Results: Using a specific statistical procedure, we established that AAO that discriminated EO-from LO-AD was 66. Compared with the LO-AD group, the EO-AD group showed longer duration of illness and a higher educational level as well as less severe functional impairment and delusions. Conclusions: Differences in sociodemographic and clinical characteristics, such as duration of illness, education and delusion severity, suggested the involvement of different pathogenic processes. Additional studies are needed to further investigate the mechanisms underlying the disorder in the two sub-groups of AD patients.
Highlights
In neurodegenerative diseases, age at onset (AAO) is an important factor in describing patients’ clinical characteristics and may be useful in selecting subgroups with more homogeneous pathogenic mechanisms and illness outcomes.In Alzheimer’s disease (AD) patients, AAO varies from 40 to 90 years
Patients with an AAO ≤ 66 years were considered included in the Early Onset (EO) group and those with an AAO > 66 years were included in the Late Onset (LO) group
We applied admixture analysis to investigate a large sample of AD patients
Summary
Age at onset (AAO) is an important factor in describing patients’ clinical characteristics and may be useful in selecting subgroups with more homogeneous pathogenic mechanisms and illness outcomes.In Alzheimer’s disease (AD) patients, AAO varies from 40 to 90 years. Age at onset (AAO) is an important factor in describing patients’ clinical characteristics and may be useful in selecting subgroups with more homogeneous pathogenic mechanisms and illness outcomes. Unlike other neuropsychiatric conditions, such as obsessive-compulsive disorder [4], bipolar disorder [5] and schizophrenia [4,5,6], in AD age was established on a clinical basis with no real statistical foundation. This is not just a theoretical issue, because AAO could be an important criterion for exploring the clinical, neurobiological and genetic heterogeneity of AD. AAO might contribute to facilitating the identification of OPEN ACCESS
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