26 Ethnicity & Disease, Volume 14, Winter 2004 COGNITIVE STATUS AND INCIDENT DISABILITY IN OLDER MEXICAN AMERICANS: FINDINGS FROM THE HISPANIC ESTABLISHED POPULATION FOR THE EPIDEMIOLOGICAL STUDY OF THE ELDERLY Objective: To determine the effects of base- line cognitive function on incidence of dis- ability in activities of daily living (ADL) in ini- tially non-disabled Mexican-American elderly over a 7-year period. Design: A prospective cohort study. Setting: Southwestern United States: Texas, California, Arizona, New Mexico, and Colo- rado. Participants: A population-based sample of Mexican Americans aged 65 and over who completed the Mini-Mental State Examination (MMSE) and other relevant variables at base- line. The sample at baseline consisted of 2731 subjects, of which 2431 were non-ADL dis- abled. Measurements: In-home interviews in 1993– 94, 1995–96, 1998–99, and 2000–2001 as- sessed sociodemographic variables, selected medical conditions (stroke, cancer, diabetes, arthritis, and hip fracture), cognitive function, depressive symptomatology, and ADLs. Results: In a Cox proportional regression anal- ysis, a significant relationship was evident be- tween MMSE score at baseline and risk of in- cident ADL disability over a 7-year period. Among non-disabled subjects at baseline, the hazard ratio of any new ADL limitation was 1.58 (95% CI, 1.18–2.12) for those with im- paired cognition (MMSE score 0–21), 1.38 (95% CI, 1.04–1.82) for low normal cognition (MMSE score 22–24), and 1.30 (95% CI, 1.02– 1.66) for normal cognition (MMSE score 25– 28) when compared to subjects with high-nor- mal cognition (MMSE score 29–30), adjusting for sociodemographic variables, presence of selected medical conditions and depressive symptoms at baseline. Similar results were also found when MMSE score was used as a con- tinuous variable. Among non-disabled subjects at baseline, each unit increase in MMSE score decreased the risk of onset of any ADL limi- tation over a 7-year follow-up period, control- ling for relevant variables at baseline (HR50.97; 95% CI, 0.95–0.99). Conclusion: Low MMSE score was associated with increased risk for incident ADL disability over a 7-year period in older Mexican Ameri- cans. Given the social, economic, and health impact of cognitive impairment, these findings suggest a need to develop effective interven- tion programs that delay or prevent the onset Mukaila A. Raji, MD; Soham Al Snih, MD; Laura A. Ray, MPA; Kushang V. Patel, MPH; Kyriakos S. Markides, PhD INTRODUCTION Functional disability and loss of in- dependence, irrespective of their causes, have been linked with poor quality of life, nursing home placement, and death. 1–3 Intact cognitive status is crucial for maintaining optimal social and phys- ical functioning. Several studies have ex- amined the relationship between cogni- tive status and functional decline. 4–7 Leveille et al 6 found a significant re- lationship between poor cognition and increasing functional difficulty among older White women, but not among older Black women after controlling for age and education. Similarly, Moritz et al, 4 using data from the New Haven Es- tablished Population for the Epidemio- logical Study of the Elderly (EPESE), showed that the odds of reporting dis- ability in Activities of Daily Living (ADLs) at the 3-year follow-up were about 2.5 times greater in subjects with of cognitive and ADL disability in the elder- ly. (Ethn Dis. 2004;14:26–31) Key Words: MMSE, Activities of Daily Liv- ing, Aging, Mexican Americans From the Department of Internal Med- icine (MAR, SAS), Center on Aging (MAR, SAS, LAR, KVP, KSM), and Department of Preventive Medicine and Community Health (SAS, LAR, KVP, KSM), University of Texas Medical Branch, Galveston, Texas. Address correspondence and reprint re- quests to Mukaila Raji, MD; Sealy Center on Aging, 301 University Blvd; The Univer- sity of Texas Medical Branch; Galveston, TX 77555-0460; 409-772-1987; 409-772- 8931 (fax); muraji@utmb.edu low cognitive ability at baseline com- pared with those with normal cognitive ability. Data from the Nun Study 5 also showed that older women with low-nor- mal cognitive function on the Mini Mental State Examination (MMSE) at baseline had twice the risk of ADL dis- ability at follow-up relative to those with high-normal cognition. In a pop- ulation-based cohort study of commu- nity-dwelling New Haven, Connecticut residents, subjects with the least efficient cognitive status were more likely (RR52.0) to develop functional depen- dence at 3-year follow-up, after adjust- ment for relevant confounders. 7 A few studies have documented a significantly higher prevalence of cog- nitive impairments among elderly His- panics compared to non-Hispanic Whites. 8–9 Using data from the Hispanic Established Population for the Epide- miological Study of the Elderly (H- EPESE), Black et al 10 reported a signif- icant cross-sectional association between cognitive status and chronic health con- ditions among older Mexican Ameri- cans. However, little is known about as- sociations between cognitive function- ing and incident disability among elder- ly Mexican Americans, a rapidly growing segment of the United States population. 11 Given the lack of longitudinal re- search examining cognitive function in this ethnic group, we conducted a study to determine whether poor cognitive function at baseline, measured by MMSE, in subjects initially free of ADL disability, is associated with any ADL disability over a 7-year period in a large area probability sample of older Mexi-