Executive function, more than global cognition, predicts functional decline and mortality in elderly women.
BACKGROUND
Functional impairment in community-dwelling older adults is common and is associated with poor outcomes. Our goal was to compare the contribution of impairment in executive function or global cognitive function to predicting functional decline and mortality.


METHODS
We studied 7717 elderly women enrolled in a prospective study (mean age 73.3 years) and identified women with poor baseline executive function (score > 1 standard deviation [SD] below the mean on the Trail Making Test B (Trails B; n = 957, 12.4%), poor global cognitive function (score > 1 SD below the mean on a modified Mini-Mental State Examination [mMMSE], n = 387, 5.0%), impairment in both (n = 249, 3.2%), or no impairment (n = 6124, 79.4%). We compared level of functional difficulty (Activities of Daily Living [ADLs] and Instrumental ADLs [IADLs]) at baseline and at 6-year follow-up and survival at follow-up. We also determined if the association was independent of age, education, depression, medical comorbidities, and baseline functional ability.


RESULTS
At baseline, women with Trails B impairment only or impairment on both tests reported the highest proportion of ADL and IADL dependence compared to the other groups. At the 6-year follow-up after adjusting for age, education, medical comorbidities, depression, and baseline ADL or IADL, women with only Trails B impairment were 1.3 times more likely to develop an incident ADL dependence (adjusted odds ratio [OR] = 1.34; 95% confidence interval [CI], 1.07-1.69) and 1.5 times more likely to develop a worsening of ADL dependence (adjusted OR = 1.48; 95% CI, 1.16-1.89) when compared to women with no impairment on either test. In addition, women with only Trails B impairment had a 1.5-fold increased risk of mortality (adjusted hazard ratio [HR] = 1.48; 95% CI, 1.21-1.81). In contrast, women with impairment on only mMMSE were not at increased risk to develop incident ADL or IADL dependence, a worsening of ADL or IADL dependence, or mortality.


CONCLUSIONS
Compared to women with no impairment, women with executive function impairment had significantly worse ADL and IADL function cross-sectionally and over 6 years. Individuals with executive dysfunction also had increased risk of mortality. These results suggest that screening of executive function can help to identify women who are at risk for functional decline and decreased survival.
Johnson
Julene K
JK
UCSF Department of Neurology, Memory and Aging Center, 350 Parnassus, Suite 706, San Francisco, CA 94117, USA. jjohnson@memory.ucsf.edu
Lui
Li-Yung
LY
Yaffe
Kristine
K
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000401:mortality* / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D015577:Geriatric Assessment; D006304:Health Status; D006801:Humans; D009043:Motor Activity / Q000502:physiology*; D012737:Sex Factors; D013997:Time Factors