Modifiable risk factors for Alzheimer disease and subjective memory impairment across age groups

Stephen T Chen; Prabha Siddarth; Linda M Ercoli; David A Merrill; Fernando Torres-Gil; Gary W Small

doi:10.1371/journal.pone.0098630

Modifiable risk factors for Alzheimer disease and subjective memory impairment across age groups

PLoS One. 2014 Jun 4;9(6):e98630. doi: 10.1371/journal.pone.0098630. eCollection 2014.

Authors

Stephen T Chen¹, Prabha Siddarth¹, Linda M Ercoli², David A Merrill¹, Fernando Torres-Gil³, Gary W Small²

Affiliations

¹ Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California, United States of America.
² Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California, United States of America; UCLA Longevity Center on Aging, University of California Los Angeles, Los Angeles, California, United States of America.
³ David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; Department of Public Policy, UCLA School of Public Affairs, University of California Los Angeles, Los Angeles, California, United States of America.

Abstract

Introduction: Previous research has identified modifiable risk factors for Alzheimer's disease (AD) in older adults. Research is limited on the potential link between these risk factors and subjective memory impairment (SMI), which may precede AD and other dementias. Examination of these potential relationships may help identify those at risk for AD at a stage when interventions may delay or prevent further memory problems. The objective of this study was to determine whether risk factors for AD are associated with SMI among different age groups.

Method: Trained interviewers conducted daily telephone surveys (Gallup-Healthways) of a representative community sample of 18,614 U.S. respondents, including 4,425 younger (age 18 to 39 years), 6,365 middle-aged (40 to 59 years), and 7,824 older (60 to 99 years) adults. The surveyors collected data on demographics, lifestyles, and medical information. Less education, smoking, hypertension, diabetes, less exercise, obesity and depression, and interactions among them, were examined for associations with SMI. Weighted logistic regressions and chi-square tests were used to calculate odds ratios and confidence intervals for SMI with each risk factor and pairwise interactions across age groups.

Results: Depression, less education, less exercise, and hypertension were significantly associated with SMI in all three age groups. Several interactions between risk factors were significant in younger and middle-aged adults and influenced their associations with SMI. Frequency of SMI increased with age and number of risk factors. Odds of having SMI increased significantly with just having one risk factor.

Conclusions: These results indicate that modifiable risk factors for AD are also associated with SMI, suggesting that these relationships occur in a broad range of ages and may be targeted to mitigate further memory problems. Whether modifying these risk factors reduces SMI and the eventual incidence of AD and other dementias later in life remains to be determined.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Adult
Age Factors
Aged
Aged, 80 and over
Alzheimer Disease / epidemiology*
Alzheimer Disease / etiology*
Female
Humans
Male
Memory Disorders / epidemiology*
Memory Disorders / etiology*
Middle Aged
Odds Ratio
Risk Factors
Surveys and Questionnaires
Young Adult

Grants and funding

Supported by the Fran and Ray Stark Foundation Fund for Alzheimer's Disease Research; the Parlow-Solomon Professorship on Aging; and the Semel Institute. No company provided support of any kind for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.