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Table 2 Studies of hypertension 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 Blood pressure Cognitive measures Adjustment variables Association with cognitive function
Chen et al. [11] (2012) Patients with type 2 diabetes; China Cross-sectional, observational 157 Mean 55 ± 7 years Hypertension defined on the basis of systolic blood pressure and diastolic blood pressure MCI identified on the basis of cognitive screening instrument None Higher prevalence of hypertension in group with MCI compared with group free of MCI. Negative correlation of presence with hypertension with cognitive scores. No findings for blood pressure as continuous measure.
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 Systolic blood pressure and diastolic blood pressure at baseline and 8 years earlier Dementia and MCI identified from screening instruments/clinical interview Age and duration of diabetes Prospective analyses: higher diastolic blood pressure 8 years earlier associated with increased risk of AD (but not MCI or any dementia) at follow-up. No findings in cross-sectional analyses.
Bruce et al. [21] (2008) Patients with type 2 diabetes participating in the Fremantle Diabetes Study; Australia 8-year retrospective, 2-year prospective, observational 205 Mean 75 ± 4 years Systolic blood pressure and diastolic blood pressure measured 8 years prior to baseline cognitive assessment Dementia and MCI identified from screening instruments/clinical interview at baseline and 2-year follow-up. ‘Cognitive decline’ defined as downward conversion between ‘normal’, MCI, and dementia. 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 Hypertension defined as use of anti-hypertensive medication or self-report of hypertension Digit Symbol Coding (primary outcome), MMSE, Rey Auditory Verbal Learning, and Stroop (secondary outcomes) Age Association of hypertension with poorer performance on Digit Symbol Coding. No findings for other cognitive tests.
Hassing et al. [19] (2004) OCTO-Twin Study of people without diabetes/hypertension, diabetes or hypertension alone, or co-morbid diabetes/hypertension; Sweden 6-year prospective, observational 258 Mean 83 ± 2 years Hypertension defined as use of anti-hypertensive medication or on the basis of systolic blood pressure and diastolic blood pressure from medical records MMSE administered at baseline and at 2-year intervals, dementia diagnosis prevalent at baseline, and incident dementia diagnosis Age, sex, education, smoking, angina, MI, CHF, stroke, and TIA Co-morbid diabetes/hypertension associated with steeper decline on MMSE (compared with group free of both conditions).
Statistically non-significant trend for higher prevalence and incidence of dementia in co-morbid diabetes/hypertension group than in remaining groups.
Johnson et al. [22] (2012) National cohort of veterans with diabetes; USA 2-year retrospective, observational study of hospital records 377,838 Mean 76 ± 6 years ICD codes for hypertension at baseline (2 years before analysis of incident dementia) ICD codes for incident dementia diagnosis Age, ethnicity, geographic area, duration of diabetes, co-morbidity according to HCC scores, and medication use 8 % increased risk of developing dementia during follow-up in patients with co-morbid hypertension at baseline.
Decreased risk in patients on anti-hypertensive medication (effect size dependent on medication), except for increased risk in patients receiving α-adrenoceptor blockers.
Manschot et al. [20] (2006) Patients with type 2 diabetes participating in the Utrecht Diabetic Encephalopathy Study; The Netherlands Cross-sectional, observational 122 Mean 66 ± 6 years Hypertension defined on the basis of systolic blood pressure and diastolic blood pressure or use of anti-hypertensive medication Composite scores on five cognitive domains from 11 cognitive tests, estimate of pre-morbid ability, cortical atrophy, and white matter lesions Age, sex, and estimated pre-morbid ability Statistically non-significant trend for lower scores on all cognitive domains except memory in patients with hypertension. Higher blood pressure associated with higher scores on memory domain and with greater severity of white matter lesions.
Manschot et al. [25] (2007) Patients with type 2 diabetes participating in the Utrecht Diabetic Encephalopathy Study; The Netherlands Cross-sectional, observational 122 Mean 66 ± 6 years Hypertension defined on the basis of systolic blood pressure and diastolic blood pressure or use of anti-hypertensive medication Composite score from 11 cognitive tests, estimate of pre-morbid ability, cortical atrophy, and white matter lesions Age, sex, and estimated pre-morbid ability Statistically non-significant trend for lower cognitive function in patients with hypertension (reaches statistical significance in final model including age, estimated pre-morbid ability, lipid-lowering drugs, and history of any vascular event). Higher blood pressure associated with greater severity of white matter lesions.
Umegaki et al. [16] (2014) Patients with type 2 diabetes; Japan 6-year prospective, observational 79 Mean 74 ± 5 years Mean of systolic blood pressure and diastolic blood pressure 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 bases of composite score and individual cognitive tests. None No association
Williamson et al. [17] (2014) Patients with type 2 diabetes participating in ACCORD-MIND blood pressure arm, with systolic blood pressure goal of 120 versus 140 mmHg; North America 40-month trial on blood pressure, lipids, and glycemic control 1,439 Mean 62 ± 6 years Successful manipulation of blood pressure (groups differed on blood pressure 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 treatment and control groups. Greater reduction in total brain volume in intervention than in control group.
  1. ACCORD-MIND, Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes; AD, Alzheimer’s dementia; CHF, congestive heart failure; HCC, Centers for Medicare and Medicaid Services’ Hierarchical Condition Categories; ICD, International Classification of Diseases; MCI, mild cognitive impairment; MI, myocardial infarction; MMSE, Mini-Mental State Examination; OCTO-Twin Study, Origin of Variance in the Old Old Study: Octogenarian Twins; TIA, transient ischemic attack