Assessment of risk factors for earlier onset of sporadic Alzheimer's disease dementia

Background: Pharmacological treatment has mild effects for patients with Alzheimer's disease dementia (AD); therefore, the search for modifiable risk factors is an important challenge. Though risk factors for AD are widely recognized, elements that influence the time of dementia onset have not been comprehensively reported. We aimed to investigate which risk factors might be related to the age of onset of AD in a sample of patients with highly variable educational levels, taking into account the Framingham risk scoring as the sole measure of vascular risk. Subjects and Methods: We included 209 consecutive late-onset AD patients to find out which factors among educational levels, coronary heart disease risk estimated by way of Framingham risk scores, history of head trauma or depression, surgical procedures under general anesthesia, family history of neurodegenerative diseases, gender, marital status and APOE haplotypes might be related to the age of dementia onset in this sample of patients with low mean schooling. Results: Mean age of AD onset was 73.38 +/- 6.5 years old, unaffected by schooling or family history of neurodegenerative diseases. Patients who were APOE-epsilon 4 carriers, married, or with history of depression, had earlier onset of AD, particularly when they were women. Coronary heart disease risk was marginally significant for later onset of AD. Conclusions: APOE haplotypes, marital status and history of depression were the most important factors to influence the age of AD onset in this sample. While midlife cerebrovascular risk factors may increase incidence of AD, they may lead to later dementia onset when present in late life.