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Table 1 Studies of dyslipidemia and cognitive function in type 2 diabetes

From: The impact of diabetes on cognitive decline: potential vascular, metabolic, and psychosocial risk factors

Study Sample Design Number Baseline mean age Lipids Cognitive measures Adjustment variables Association with cognitive function
Bruce et al. [14] (2008) Patients with type 2 diabetes participating in the Fremantle Diabetes Study; Australia 8-year retrospective, observational 302 Mean 76 ± 5 years Total cholesterol and HDL at baseline and 8 years earlier Dementia and MCI identified from screening instruments/clinical interview Waist-hip ratio No associations in unadjusted cross-sectional or prospective analyses. Higher total cholesterol 8 years earlier protective of cognitive impairment short of dementia (but not dementia or all cognitive impairment) at baseline (finding independent of waist-hip ratio)
Chen et al. [9] (2011) Patients with type 2 diabetes; China Cross-sectional, observational 101 Mean 63 ± 8 years Total cholesterol, LDL, and HDL MCI identified on the basis of cognitive screening instrument None Higher triglycerides, total cholesterol, and LDL in MCI group compared with group free of MCI. Negative correlation of total cholesterol with scores on cognitive screening instrument in patients with MCI. No finding for HDL.
Chen et al. [11] (2012) Patients with type 2 diabetes; China Cross-sectional, observational 157 Mean 55 ± 7 years Triglycerides, total cholesterol, LDL, and HDL MCI identified on the basis of cognitive screening instrument None No association
Cukierman-Yaffe et al. [13] (2009) Patients with type 2 diabetes participating in ACCORD-MIND; North America Cross-sectional analysis of trial on blood pressure, lipids, and glycemic control 2,977 Mean 63 ± 6 years Hyperlipidemia defined as use of lipid-lowering medication or untreated LDL cholesterol Digit Symbol Coding (primary outcome), MMSE, Rey Auditory Verbal Learning, and Stroop (secondary outcomes) Age Association of hyperlipidemia with better performance on Digit Symbol Coding. No findings for other cognitive tests.
Perlmutter et al. [10] (1988) Patients with type 2 diabetes; USA Cross-sectional, observational 246 Range 55-74 years Triglycerides and total cholesterol Digit Symbol Coding, Digit Span, and simple reaction time Plasma glucose, HbA1c, body mass index, and history of hypertension Lower cognitive function in ‘high’ compared with ‘low’ triglyceride groups (fully adjusted analysis); association of cholesterol with triglyceride (unadjusted analysis).
Umegaki et al. [16] (2014) Patients with type 2 diabetes; Japan Six-year prospective, observational 79 Mean 74 ± 5 years Mean of HDL and LDL measured at baseline and annual follow-ups Composite score from MMSE, Digit Symbol Coding, Stroop, and word recall. Analyses of ‘decliners’ versus ‘non-decliners’ on the basis of composite score and individual cognitive tests. Age, education, estimated glomerular filtration rate, renin-angiotensin system inhibitor use, paraventricular hyperintensities, and deep white matter hyperintensities Lower mean 6-year HDL in ‘decliners’ compared with ‘non-decliners’ on composite score and Stroop (unadjusted analysis). No finding for LDL. Mean 6-year HDL significant predictor in model of risk of decline on composite score (fully adjusted analysis).
Williamson et al. [17] (2014) Patients with type 2 diabetes participating in ACCORD-MIND lipid arm, receiving simvastatin + fenofibrate or simvastatin + placebo; North America 40-month trial on blood pressure, lipids, and glycemic control 1,538 Mean 62 ± 6 years Successful manipulation of cholesterol levels (groups differed on cholesterol following intervention). Total brain volume at baseline and 40 months, Digit Symbol Coding (primary outcome), MMSE, Rey Auditory Verbal Learning, and Stroop (secondary outcomes) at baseline and 20 and 40 months Glycemia treatment arm, visit effect, clinical center, and history of cardiovascular disease No difference in 20- or 40-month cognitive decline or 40-month change in total brain volume between intervention and control groups of lipid trial
Van Harten et al. [12] (2007) Patients with type 2 diabetes; The Netherlands Cross-sectional, observational 92 Mean 73 ± 6 years Total cholesterol/HDL ratio Cognitive screening instruments, composite scores of four cognitive domains derived from scores on battery of 10 cognitive tests Duration of diabetes, HbA1c, insulin use, hypertension, and polyneuropathy No association
Yanagawa et al. [15] (2011) Patients with diabetes receiving exercise program four times per week versus none; Japan 12-week trial on physical exercise intervention 16 Mean 71 ± 4 years HDL and LDL (no intervention effect on HDL and LDL) MMSE, word recall, Digit Symbol Coding, Stroop, and Trail-Making Test Age, education, and body mass index No difference in cognitive function between treatment groups following intervention
  1. ACCORD-MIND, Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes; HDL, high-density lipoprotein; LDL, low-density lipoprotein; MCI, mild cognitive impairment; MMSE, Mini-Mental State Examination