Cognitive Decline in Type 2 Diabetes Mellitus and the Relation with Vascular Risk Factors: A Longitudinal Population-Based Study
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Background/Aims Type 2 diabetes mellitus (T2DM) and co-morbid vascular risk factors (e.g. HbA1c, hypertension, obesity) are associated with decrements in cognitive functioning, especially in the elderly. We hypothesized that these cognitive decrements increase over time with advancing age. The current longitudinal study examined the development in cognitive functioning in T2DM over a 4-year interval. Methods An extensive neuropsychological assessment and vascular and metabolic risk factor profiles were obtained from 47 T2DM patients (mean age: 66.9 ± 5.6) and 26 matched-control participants (mean age: 63.4 ± 5.4). Cognitive test scores divided into five cognitive domains (Abstract Reasoning, Memory, Information Processing Speed, Attention and Executive Functioning and Visuoconstruction) and expressed as standardised z-scores, adjusted for age. Results T2DM patients performed worse than controls on the domains Abstract Reasoning (effect size (ES): -.07 to -.07), Memory (ES: -.21 to -.16), Information Processing Speed (ES: -.33 to -.54) and Attention and Executive Functioning (ES: -.16 to -.26), but this difference was only significant for the domain Information Processing Speed. No Time and GroupxTime interaction effects were observed in cognitive functioning. However, a trend for interaction was observed on the domain Information Processing Speed (p=.066). Body Mass Index was a predictor for cognitive decline on the domain Visuoconstruction (>BMI predicts better performance on Visuoconstruction) (p<.05). Conclusion Even though we did find changes in cognitive performance, contrary to our hypothesis accelerated cognitive decline was not observed in T2DM patients. Co-morbid vascular risk factors associated with T2DM, did not consistently predict worse cognitive performance. In this study sample BMI was related to performance on the domain Visuoconstruction.