IADL Limitations Linked to Mortality and Cognitive Impairment in Older Puerto Rican Adults

TL;DR

This study finds that limitations in daily living tasks are linked to higher mortality and cognitive decline in older Puerto Rican adults.

Contribution

The study provides new insights into the longitudinal relationship between IADL limitations and cognitive impairment in an underrepresented Puerto Rican population.

Findings

Increased baseline IADL limitations are associated with higher mortality risk.

Worsening IADL limitations over time are linked to increased cognitive impairment risk.

Associations between IADL limitations and outcomes are moderated by sex and education.

Abstract

Limitations in instrumental activities of daily living (IADL) are an important clinical indicator of dementia severity and risk factors for mortality. Research suggests that IADL limitations are a predictor of future cognitive decline. A greater understanding of this longitudinal association is needed, especially in underrepresented samples with a high risk of Alzheimer’s disease, such as older adults in Puerto Rico. This study examined these associations using data from Waves 1 (2002/2003), 2 (2006/2007), 3 (2020/2021), and 4 (2022/2024) of the Puerto Rican Elder: Health Conditions Study (PREHCO), a longitudinal, population-based study of Puerto Rican adults aged 60 and older. The sample included adults who were cognitively unimpaired at baseline (Mini Mental Cabán score of 11 or higher) with at least one wave of follow-up data (n = 2,630, mean age=71.33, SD = 8.25; 59.5% female). Participants self-reported limitations on seven IADLs and were screened for cognitive impairment at each wave. National Death Index data was integrated. Overall, increased baseline IADL limitations were associated with an increased risk of death [hazards ratio (HR)=1.05, p<.001], as were increases in IADL limitations over time (HR = 1.04, p<.001). When accounting for this mortality risk using inverse-probability weighting, increases in IADL limitations remained significantly related to a heightened risk of cognitive impairment (HR = 1.08, p<.001). In contrast, baseline IADL limitations did not (p=.102). Exploratory analyses revealed that these associations were moderated by sex and education. Findings highlight the need for early screening and interventions tailored to older Puerto Rican adults’ specific needs and lived experiences to sustain functional independence in mid-life.