EXAMINING DEMENTIA CLASSIFICATION IN THE NATIONAL HEALTH AND AGING TRENDS STUDY

Abstract

In recent years, research has begun exploring cognitive reserve (i.e., Stern, 2009) to understand individual differences in susceptibility to age-related brain changes or Alzheimer's disease and related dementia pathology. Cognitive reserve suggests that there may be psychosocial interventions that could slow cognitive aging or reduce the onset of dementia. A longitudinal survey design was utilized with the National Health and Aging Trends Study (NHATS, 2011) which is a nationally-collected and publicly available dataset which annually collects self-reported measures of cognitive impairment. A sample of 3,287 U.S. Medicare beneficiaries aged 65 and older met the criteria for the study (n=3,287). Three different dementia classifications - those who stayed the same, declined, or reversed - using cognitive scores from time 1 and time 5 (5 years) were compared. Based on assumptions underlying the cognitive reserve hypothesis, a discriminant analysis was used to identify factors that differentiated the three groups. Results showed that education and instrumental activities of daily living (IADLs) were most relevant for those who “stayed the same” from time 1 to time 5. Age and Instrumental activities of daily living (IADLs) were most influential with those who “declined”, whereas education and social interaction/participation were most important among those who “reversed,” i.e., their cognitive functioning improved from wave 1 to wave 5. A discussion about cognitive reserve, diagnosis and assessment, and the significant factors that worsened or improved cognitive functioning will ensue. Future studies are needed to examine these factors in more depth specifically to consider differential contributions of each factor to cognitive decline over time. Implications for intervention also will be considered.