Impact of Hypertension, Diabetes, and Dyslipidemia Comorbidity on Cognition among Hispanic Mexican Americans: An HABLE Study

Background: Hypertension, hyperlipidemia, and diabetes mellitus are medical diagnoses that occur at high prevalence rates among the Hispanic Mexican American population. Current research shows that each individual diagnosis is linked to cognitive decline, but this assertion is limited in that these studies have been conducted on Non-Hispanic White populations only. Additionally, an insignificant number of studies have investigated the comorbidity of these diagnoses, and how that may impact risk for cognitive impairment. This study seeks to fill this gap in the literature by determining the association between combinations of these diagnoses and cognitive functioning within a Hispanic Mexican-American population. Methods: Data were analyzed from 537 Mexican American participants who met diagnostic criteria for hypertension, dyslipidemia, and diabetes mellitus (Group 1, one diagnosis, n= 148; Group 2, two diagnoses, n=219; Group 3, three diagnoses, n=170) from the Health and Aging Brain study among Latino Elders (HABLE). Information from each participant was obtained via clinical interview (including medical history, current medications, and health behaviors), informant interview, neuropsychological testing, blood draw, and physical examination. Consensus reviews were conducted weekly to review subject data, and to establish cognitive and medical diagnoses according to national guidelines. Linear regressions analyses were utilized to examine cognitive functioning, measured through the domains of memory and verbal fluency as the dependent variable, with the independent variable consisting of the number of medical diagnoses (one, two, or three). Covariates included age, gender, and education. Results: Those in Group 1 displayed poorer performance on measures of immediate (B[SE]= -2.66[1.05], t-test = -2.52, p-value=0.012) and delayed (B[SE]= -1.59[0.77], t-test= -2.04, p-value= 0.041) memory. Differentially, those in Group 2 showed poorer performance on tasks related to verbal fluency (B[SE]=-2.33[0.80], t-test= -2.88, p-value=0.004) and working memory (B[SE]=-0.59[0.24], t-test=-2.42, p-value=0.016). Group 3, which encompassed all three medical diagnoses, was not significantly related to any of the cognitive domains that were examined. Conclusion: These findings suggest that within the Hispanic Mexican American population, domains of cognitive functioning are differentially affected within each group, with Group 3 showing no significant increased risk for cognitive dysfunction. These findings do not support current research, which suggests a higher and more invariable prevalence of cognitive decline, regardless of the comorbidity of these diagnoses. Additional research is needed to investigate the neurological effects of the biological pathways associated with the varying combination of diseases, which may explain the dissimilarity in associated cognitive function.