What is a reasonable conclusion about the relationship between depression and mortality in cardiac disease?

What is a reasonable conclusion about the relationship between depression and mortality in cardiac disease?

• A. Depression causes death in cardiac disease
• B. Depression is associated with higher mortality but causation cannot be concluded
• C. There is no association
• D. Depression reduces mortality

Answer: (B)

The key idea here is that depression and mortality in cardiac disease are linked, but this does not prove that depression causes death. Observational research often shows that patients with depression have higher death rates after cardiac events, yet such studies can’t fully separate cause from correlation. Factors like how severe the heart condition is, other illnesses, health behaviors (smoking, exercise, medication adherence), and access to care can influence both depression and mortality. There’s also the possibility of reverse causation, where a worsening cardiac condition leads to more depressive symptoms. While there are plausible pathways—depression can affect adherence and lifestyle, and it may involve physiological changes like inflammation or autonomic dysfunction—these don’t, on their own, establish that depression directly causes death. That’s why the best conclusion from the evidence is that depression is associated with higher mortality, but causation cannot be concluded from the available data. It’s important to recognize the difference between association and causation. The other statements are not supported: there isn’t proven causation that depression directly causes death, there is an observed association, and there’s no consistent evidence that depression reduces mortality.

The key idea here is that depression and mortality in cardiac disease are linked, but this does not prove that depression causes death. Observational research often shows that patients with depression have higher death rates after cardiac events, yet such studies can’t fully separate cause from correlation. Factors like how severe the heart condition is, other illnesses, health behaviors (smoking, exercise, medication adherence), and access to care can influence both depression and mortality. There’s also the possibility of reverse causation, where a worsening cardiac condition leads to more depressive symptoms. While there are plausible pathways—depression can affect adherence and lifestyle, and it may involve physiological changes like inflammation or autonomic dysfunction—these don’t, on their own, establish that depression directly causes death.

That’s why the best conclusion from the evidence is that depression is associated with higher mortality, but causation cannot be concluded from the available data. It’s important to recognize the difference between association and causation.

The other statements are not supported: there isn’t proven causation that depression directly causes death, there is an observed association, and there’s no consistent evidence that depression reduces mortality.