What is the Relationship between Depression, Hypertension, and Mortality in an Elderly Population?

This post will discuss a 2019 article titled, ““Association of depression with mortality in an elderly treated hypertensive population” written by Chowdhury, Berk, Nelson, Wing, & Reid. This study broadly aimed to examine the association between depression and mortality among an elderly sample afflicted with and being treated for hypertension. The authors of this article also sought to examine and determine possible predictors of “incident depression” (i.e., depression that was developed during enrollment in the study).

What did they do?

Data from elderly patients (65-84 years old) enrolled in the Second Australian National Blood Pressure Study (N = 6,083) were examined. Specifically, the authors of this creative study examined several pre-trial variables (e.g., health history, educational history, geographic location, etc.) as well as in-trial variables (e.g., use of hypertensive medication, new onset diabetes, development of depression, etc.) to broadly determine how these factors are related to mortality rates in their sample.

Why did they do it?

The authors of this article honed in on elevated blood pressure as one of the leading risk factors for cardiovascular disease, which contributes greatly to mortality. When hypertension is coupled with depression (i.e., the presence of comorbidity), the risk of cardiovascular disease and consequently mortality is greatly increased. Due to the limited and inconsistent research on the specifics regarding the association between hypertension and depression in elderly patients (a group that is certainly at high risk for both illnesses), the authors of this article deemed it important to explore the association of both newly developed and pre-existing depression with mortality over an 11 year follow up. The authors also sought to explore predictors of incident depression in the same population.

How did they do it?

As mentioned previously, data from the Second Australian National Blood Pressure Study were examined. Blood pressure of participants was recorded annually, as well as at each patient visit to their family practitioner. Within this study, participants were classified as having depression based on receipt of a diagnosis of depression and/or having an antidepressant prescription. Participants with depression were then sub-classified into “pre-existing depression” (i.e., depression existed prior to enrollment in the study) or “incident depression” (i.e., depression developed during the study). Rates of all-cause and cardiovascular mortality were then compared between groups. Additionally, predictors of incident depression were analyzed.

What did they find?

Approximately 5% of participants were identified as having pre-existing depression at baseline. Another 15% of participants were identified as developing depression during the follow up period of the study. There were a total of 1,830 all-cause deaths over the course of the study period, 940 of which were strictly cardiovascular related. Both categories of mortality (all-cause and cardiovascular) were higher among participants with any lifetime depression when compared to those with no history of depression.

With regard to the development of depression during the trial period, the following variables emerged as significant predictors: age (>75 years), female gender, smoking regularly at study onset, and developing diabetes during the trial period.

What does it all mean (our take)?

This article creatively used data from a longitudinal dataset to examine if there is a relationship between depression and mortality in this particular population. The emphasis of this study is clearly on the unique and complex relationship between physical and mental health in elderly individuals - an area of work that is certainly growing and arising as quite important to evaluate.

Do results from this study indicate that depression causes mortality? No (the authors never state that this is the case, either!). But, do the results seem to indicate that there appears to be at least some relationship between complex chronic physical health problems and mental health that may actually increase the risk of mortality? Yes.

The elderly population is at an elevated risk for a laundry list of physical health problems - this is fairly well-established. What we cannot forget is that this same group of individuals is also at risk for mental health difficulties, and based on results from this study clinicians should prioritize evaluating the mental well-being of their elderly patients. This would be a small task that could lead to valuable positive effects.