Risk factors for age at onset of dementia due to Alzheimer's disease in a sample of patients with low mean schooling from Sao Paulo, Brazil

Objective: In view of the mild effects of pharmacological treatment for dementia due to Alzheimer's disease (AD), the search for modifiable risk factors is an important challenge. Although risk factors for AD are widely recognized, elements that influence the time of onset of the dementia syndrome have not been comprehensively reported. We aimed to investigate which risk factors might be associated with the age at onset of AD in a sample of patients with low mean schooling from Sao Paulo, Brazil. Methods: We included 210 consecutive patients with late-onset AD to investigate whether education, gender, nationality, urban living and sanitation, occupation, cognitive and physical inactivity, head trauma, depression, systemic infections, surgical interventions, cerebrovascular risk factors, family history of neurodegenerative diseases or cardiovascular diseases and apolipoprotein E gene (APOE) haplotypes might be related to the age at AD onset. Results: Each copy of APOE-epsilon 4 led to onset of AD almost 2 years earlier, while depression, smoking, higher body mass index and family history of cardiovascular diseases were also highly significant. Protective factors included non-Brazilian nationality, use of a pacemaker and waist circumference. Cerebrovascular risk factors had a mild combined effect for earlier onset of AD. Conclusion: APOE haplotypes, depression, nationality and cerebrovascular risk factors were the most important elements to influence the age at AD onset in this sample, whereas gender, education, occupation and physical activities had no isolated effects over the age at onset of this dementia syndrome. Copyright (C) 2014 John Wiley & Sons, Ltd.