The mean (SD) age of the study population was 60.9 (8.8) years. The majority were women (63.9%), Caucasian (64.5%) and highly educated (59.6% with a Bachelor’s or graduate degree). Nearly one-third (31.9%) was currently using medications for hypertension. A total of 112 (13.1%) of the study population fit the expanded NCEP definition for MetS. Of those, 75 (67%) met three criteria, 30 (26.8%) met four, and 7 (6.3%) met all five criteria. Among those with MetS, the most common criterion met was hypertriglyceridemia (n = 90, 80.4%), followed by hypertension (n = 86, 76.8%), abdominal obesity (n = 82, 73.2%), low HDL-C (n = 66, 58.9%) and hyperglycemia (n = 56, 50%). Subjects with MetS were more likely to be Hispanic and, as expected, have higher blood pressure, fasting glucose, TG and BMI and lower HDL-C compared to those without MetS ().
Baseline characteristics for study subjects with cognitive testing (n = 853) by the presence of the metabolic syndrome
Participants with MetS had non-significantly lower scores on the verbal learning factor (β = −.14 [SE(β) = 0.09], p = .15) compared to participants without MetS (). For each additional MetS criterion met, scores decreased by 6% of a SD on the measure of global cognition (β =−.06 [SE(β) = 0.03], p = .01), by 5% of a SD on the verbal learning factor (β = −.05 [SE(β) = 0.03], p = .06), and by 6% of a SD on the semantic factor (β = −.06 [SE(β) = 0.03], p = .04). The MetS was not associated with executive function, logical memory or visual memory ().
Beta coefficients from linear regression models* of associations between the metabolic syndrome and six measures of cognition for 853 study subjects
Increases in SBP and TG were individually associated with lower semantic memory (). Lower global cognitive abilities were correlated with individual increases in TG (β = −.07 [SE(β) = 0.03], p = .02). When mutually adjusted as continuous variables, only increasing SBP was statistically significantly correlated with lower cognitive function (in semantic memory: β = −.08 [SE(β) = 0.04], p = .04).
Beta coefficients from linear regression models* of associations between components of the metabolic syndrome individually modeled as continuous variables and cognitive function for 853 study subjects
Using the NCEP-defined criteria for MetS, hypertension was individually associated with lower verbal learning (β = −.17 [SE(β) = 0.08], p = .04), semantic memory (β = −.28 [SE(β) = 0.08], p = .0006) and global cognition (β = −.15 [SE(β) = 0.07], p = .04). Hypertriglyceridemia and hyperglycemia were individually associated with lower semantic memory, and low HDL-C and hypertriglyceridemia were significantly individually associated with lower global cognition (). When all MetS criteria were mutually adjusted in regression models, hypertension was the only MetS risk factor that was consistently independently inversely associated with verbal learning, semantic memory and global cognition (). MetS criteria (modeled either as continuous or categorical variables) were not associated (either individually or independently) with executive function, logical memory or visual memory (results not shown).
Beta coefficients from linear regression models* of associations between individual NCEP metabolic syndrome characteristics (categorical variables) and cognitive function
We explored whether gender modified the association between the MetS criteria and semantic memory. Mutually adjusted associations were several magnitudes higher in women for abdominal obesity (β = .34 [SE(β) = 0.10], p = .0005) and hyperglycemia (β = −.32 [SE(β) = 0.14], p=.03) than men (β = .05 [SE(β) = 0.14], p = .73, and (β = −.04 [SE(β) = 0.14], p = .78, respectively), but were not appreciably different for hypertension.