Correcting Bias Caused by Missing Data in the Estimate of the Effect of Apolipoprotein ε4 on Cognitive Decline

Associations between Visual Acuity and Cognitive Decline in Older Adulthood: A 9-Year Longitudinal Study

OBJECTIVE

Emerging evidence suggests low vision may be a modifiable risk factor for cognitive decline. We examined effects of baseline visual acuity (VA) on level of, and change in, cognitive test performance over 9 years.

METHOD

A population-based sample of 1,621 participants (average age 77 years) completed a comprehensive neuropsychological evaluation and VA testing at baseline and reassessed at nine subsequent annual visits. Linear regression modeled the association between baseline VA and concurrent cognitive test performance. Joint modeling of a longitudinal sub-model and a survival sub-model to adjust for attrition were used to examine associations between baseline VA and repeated cognitive test performance over time.

RESULTS

Better baseline VA was associated cross-sectionally with younger age, male sex, greater than high school education, and higher baseline neuropsychological test scores on both vision-dependent (B coefficient range -0.163 to -0.375, p = .006 to <.001) and vision-independent tests (-0.187 to -0.215, p = .003 to .002). In longitudinal modeling, better baseline VA was associated with slower decline in vision-dependent tests (B coefficient range -0.092 to 0.111, p = .005 to <.001) and vision-independent tests (-0.107 to 0.067, p = .007 to <.001).

CONCLUSIONS

Higher VA is associated with higher concurrent cognitive abilities and slower rates of decline over 9 years in both vision-dependent and vision-independent tests of memory, language, and executive functioning. Findings are consistent with emerging literature supporting vision impairment in aging as a potentially modifiable risk factor for cognitive decline. Clinicians should encourage patient utilization of vision assessment and correction with the added aim of protecting cognition.

The effect of missing data and imputation on the detection of bias in cognitive testing using differential item functioning methods

Background

Item response theory (IRT) methods for addressing differential item functioning (DIF) can detect group differences in responses to individual items (e.g., bias). IRT and DIF-detection methods have been used increasingly often to identify bias in cognitive test performance by characteristics (DIF grouping variables) such as hearing impairment, race, and educational attainment. Previous analyses have not considered the effect of missing data on inferences, although levels of missing cognitive data can be substantial in epidemiologic studies.

Methods

We used data from Visit 6 (2016–2017) of the Atherosclerosis Risk in Communities Neurocognitive Study (N = 3,580) to explicate the effect of artificially imposed missing data patterns and imputation on DIF detection.

Results

When missing data was imposed among individuals in a specific DIF group but was unrelated to cognitive test performance, there was no systematic error. However, when missing data was related to cognitive test performance and DIF group membership, there was systematic error in DIF detection. Given this missing data pattern, the median DIF detection error associated with 10%, 30%, and 50% missingness was -0.03, -0.08, and -0.14 standard deviation (SD) units without imputation, but this decreased to -0.02, -0.04, and -0.08 SD units with multiple imputation.

Conclusions

Incorrect inferences in DIF testing have downstream consequences for the use of cognitive tests in research. It is therefore crucial to consider the effect and reasons behind missing data when evaluating bias in cognitive testing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01572-2.

Cholesteryl ester transfer protein genotype modifies the effect of apolipoprotein ε4 on memory decline in older adults

Apolipoprotein ε4 (ApoE4) is a strong genetic risk factor for sporadic Alzheimer's disease and memory decline in older adults. A single-nucleotide polymorphism in the cholesteryl ester transfer protein (CETP) gene (isoleucine to valine; V405) is associated with slower memory decline and a lower risk of Alzheimer's disease. As both genes regulate cholesterol, we hypothesized that the favorable CETPV405 allele may buffer the effect of ApoE4 on memory decline in older adults. Using linear regression, we examined the interactive effect of ApoE4 by CETPV405 on memory decline among 909 community-dwelling, nondemented, older adults (≥70 years) from the Einstein Aging Study. Episodic memory was measured using the picture version of the Free and Cued Selective Reminding Test with immediate recall (pFCSRT+IR). There was a significant ApoE × CETP interaction on decline in pFCSRT+IR scores (p = 0.01). ApoE4 carriers experienced faster decline than noncarriers among CETPI405I homozygotes (p = 0.007) and in CETPI405V heterozygotes (p = 0.015) but not in CETPV405V homozygotes (p = 0.614). Results suggest that the CETPV405 allele buffers ApoE4-associated memory decline in a gene dose-dependent manner.