There is no disease-modifying treatment for Alzheimer’s Disease and Related Dementia (ADRD). However, its pathology may occur 20 years earlier than its symptoms. Therefore, understanding cognitive decline at middle age, which might be the starting point of dementia, may be particularly important for preventing or delaying the onset of dementia. This study quantified the population with fast rates of cognitive decline at middle age, explored the distribution of cognitive trajectories, and investigated demographic, health, and socioeconomic factors associated with cognitive deterioration for Americans.
We utilized data from Health and Retirement Study (HRS) 1996 to 2014 and restricted the sample to respondents aged 50 to 64 with self-reported cognitive score (scaling 0 to 27). We computed person-specific slopes of changes in cognitive score over the study period (an average of 8 years) by running a linear regression of cognitive score on wave. Further, we defined fast rates of cognitive decline as 2 or more points decline (a slope equal to or below -2) in one’s cognitive score per wave. We identified persons with rapid cognitive decline . We further examined the distribution of slopes of individual cognitive trajectories over the whole study period. We utilized logistic regression to examine health and socioeconomic factors associated with rapidly declining cognition at middle age.
Overall, 8.7% of the population had rapidly declining cognitive function over the observation period. Being an ethnic minority (ORblack: 2.3 [95%CI: 2.0 – 2.7]), having a less than high school degree (OR: 1.7 [95%CI: 1.4 – 2]), having hypertension (OR: 1.2 [95%CI: 1.1 – 1.4]) and diabetes (OR: 1.5 [95%CI: 1.2 – 1.7], male, low income, not working or working in less cognitively demanding occupations were risk factors for experiencing fast speed of cognitive decline .
Nine percent of the middle-aged population experienced rapidly deteriorating cognitive abilities. Ethnic minorities, those with cardiovascular risk factors and lower socioeconomic status are more likely to develop rapidly declining cognition and are more vulnerable alleviating the burden of such a decline on their health and productivity.
The full study is available in Alzheimer’s and Dementia.