title: Nonmelanoma skin cancer is associated with reduced Alzheimer disease risk.
abstract: OBJECTIVE
  To explore the association of nonmelanoma skin cancer (NMSC) and Alzheimer disease (AD) in the Einstein Aging Study, an epidemiologic study of aging in New York City.
  
  
  METHODS
  Community-residing volunteers aged 70 years or older were assessed annually, followed by multidisciplinary diagnostic consensus. Cancer status and type was obtained by self-report. Cox proportional hazards models were used to test associations between NMSC and subsequent risk of developing a neurocognitive disorder. To deduce a biologically specific association between AD and NMSC, we considered 3 nested outcomes groups: only AD (probable or possible AD as the sole diagnosis), any AD (probable AD or possible AD, as well as mixed AD/vascular dementia), and all-cause dementia.
  
  
  RESULTS
  We followed 1,102 adults with a mean age of 79 years at enrollment. Prevalent NMSC was associated with reduced risk of only AD (hazard ratio = 0.21; 95% confidence interval = 0.051-0.87; p = 0.031) among subjects after adjustment for demographics, hypertension, diabetes, and coronary heart disease. APOE ε4 genotypes were available in 769 individuals. The association was similar in magnitude, but nonsignificant, when the number of APOE ε4 alleles was included in the model. No significant association was found between NMSC and subsequent development of any AD or all-cause dementia.
  
  
  CONCLUSIONS
  This population-based longitudinal study shows that individuals older than 70 years with NMSC have a significantly reduced risk of developing AD compared with individuals without NMSC. We deduce Alzheimer-specific neuroprotection, because the effect is attenuated or eliminated when considering less-specific diagnoses such as AD with another diagnosis (any AD) or all-cause dementia.
authors.affiliation: Saul B. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: White
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lipton
authors.forename: Charles B
authors.initials: CB
authors.lastname: Hall
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Steinerman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000523:psychology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008545:Melanoma; D011159:Population Surveillance / Q000379:methods; D012307:Risk Factors; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology