Association of Hypertension with Depression in Community-Dwelling Elderly Persons: Results from the ZARADEMP Project

National Committee Seventh Report criteria [11] were used for the diagnosis of hypertension. Research psychiatrists individually supervised the standardized interviews of lay interviewers doing the field study, and reassessed the cases considered to be ‘doubtful’ in the elderly homes (n = 159) [12] . A systematic control of the reliability of lay interviewers and psychiatrists was implemented to prevent reliability decay. Psychiatric cases were diagnosed according to GMS-AGECAT criteria. The specific hypothesis of the association of hypertension with depression was tested by means of logistic regression (LR) analysis. Potentially confounding factors ( table 1 ) were selected for the analysis because of their association with depression in previous research and in preliminary, bivariate models calculated here. Standard ethical principles have been maintained, according to Spanish law (article 5, 1992). The analysis of data has been completed in the subjects with full information (n = 4,136), the 667 losses being due to missing data in blood pressure measurements or other variables. Hypertension was documented in 2,523 individuals (61.0%; 41.7% were stage 1 and 19.3% were stage 2 hypertensives), and 314 of them (12.4%) were depressed. Results of LR analysis show, in the unadjusted model, that OR for depression was significantly higher in stage 2 hypertension (OR = 1.46, 95% CI = 1.12–1.90). Potential modifiers/confounders were then included in the model ( table 1 ; models 1–5), the results being similar. Finally, table 1 also shows the results of LR analysis when controlling for all variables (model 5), showing that the estimated risk for depression remains statistically significant for grade 2 hypertension (OR = 1.37, 95% CI = 1.03–1.81). The results support the hypothesized association of hypertension with depression. It might be argued that not all GMS-AGECAT cases of depression fulfill DSM-IV-TR or ICD-10 psychiatric criteria. However, this computerized diagnostic system has been shown to correspond with what psychiatrists recognize as a case for intervention [7] . Subsyndromal depression, which has also been suggested in some reports to be associated with hypertension [1] , was not approached in this study because we were more interested in potential clinical implications. Our findings are rather consistent with the report by Copeland et al. [1] . The British authors used the same GMS-AGECAT standardized diagnostic method and controlled for a number of potential risk factors. However, hypertension was self-reported and cognitive performance was not controlled. Barrett-Connor and Palinkas [4] also found an association with depression scores, but it was limited to DBP, both high and low DBP. However, their paper is not totally comparable to ours, since their sample was limited to men, depression was only assessed by a questionnaire and they only controlled for age and weight loss. The studies by Friedman et al. [2] The empirical literature in population studies does not unequivocally support clinical observations suggesting the association of hypertension with depression. A positive association has been reported in some inquiries [1] but not in others [2, 3] , and the relationship was limited to individuals with diastolic blood pressure (DBP) in some studies [4] . Differences in design make between-study comparisons difficult. Methodological difficulties are observed in previous research: some studies are based on self-reported hypertension, adjustment for potential confounders is not systematic and no studies with the exception of the investigation by Copeland et al. [1] have used a standardized psychiatric diagnosis. This study tests the hypothesis of a positive association between hypertension and depression, and tries to circumvent the described methodological difficulties. It is the baseline, crosssectional study of the ZARADEMP Project, a longitudinal, threewave epidemiological inquiry, the methodology of which has been previously described [5] . A large, stratified random sample of individuals from the census list aged 55 and over was selected. Refusal rate was 20.5%, and 4,803 people were interviewed. Residents of old age homes and other institutions were included in the community sample. An epidemiological screening design was implemented, and standardized Spanish versions of assessment instruments were used, including the Geriatric Mental State (GMS) [6] , its computerized diagnostic program, AGECAT, and the History and Aetiology Schedule [7, 8] . The history of medical diseases was documented by means of the Risk Factor Questionnaire designed by the EURODEM Workgroup [9] . The assessment of blood pressure followed World Health Organization standards, modified by the European Society of Hypertension [10], and Joint Published online: July 25, 2008