Abstract

Objective

The purpose of this study was to examine changes in cognitive function over time as measured by a telephone-delivered cognitive assessment.

Method

Cognitive and biomarker data from the Midlife in the United States (MIDUS) study were used. Missing data were excluded through listwise deletion resulting in a final sample of 2,378 adult respondents with MIDUS 2: Cognition data available at baseline (T1; Mage = 53.49, SD = 10.63) and 9-year follow up (T2; Mage = 63.64, SD = 11.35). Cognition was measured using Brief Test of Adult Cognition by Telephone (BTACT) composite z-scores (“severe” = <−2.01 SD; “mild” = −1.01 to −2.00 SD; “normal”= > −1.00 SD).

Results

A Two-Way Repeated Measures ANOVA revealed main effects for time (F1, 2,375 = 46.73, p < .001) and group (F2, 2,375 = 499.34, p < .001). BTACT scores at T1 (M = -1.06, 95% CI[−1.21, −0.92]) were significantly lower than scores at T2 (M = -0.70, 95% CI[−0.82, −0.59]). As expected, BTACT scores for the normal group (M = 0.39, 95% CI[0.35, 0.42]) were significantly greater than both the mild (M = -1.33, 95% CI[−1.36, −1.30]) and severe (M = -2.25, 95% CI[−2.33, −2.16]) groups. A significant interaction effect was observed between time and group (F2, 2,375 = 204.10, p < .001). Bonferroni post-hoc comparisons indicated that cognitive function scores significantly declined for those in the normal group, but significantly improved for those in the mild and severe groups (all ps < .001). A regression model using biomarkers as predictors of cognitive change for the impaired groups was nonsignificant.

Conclusion(s)

Improvement in the mild and severe groups was unexpected and could not be explained by cardiovascular or metabolic risk factors at T1. These findings suggest cautious interpretation of cognition scores obtained via telephone measures.

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