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Inflammation could be shared mechanism for depression, heart disease
Using Mendelian randomization, researchers found that depression and coronary heart disease shared common underlying biological mechanisms.
The study, published in Molecular Psychiatry, indicated that certain risk factors for coronary heart disease (CHD) — triglycerides and inflammation-related proteins interleukin-6 and C-reactive protein — were causally linked with depression.
“[Prior] findings indicate that CHD and depression may have shared mechanisms. However, common illnesses such as depression and CHD tend to cluster at population and individual levels, so to what extent this comorbidity is attributable to shared environmental or shared genetic factors is an outstanding question,” Golam Khandaker, PhD, from the department of psychiatry, University of Cambridge, England, and colleagues wrote.
The researchers examined whether comorbidity with depression and CHD was mostly attributable to genetic or environmental factors in 367,703 middle-aged adults of European ancestry from a population-based cohort study (UK Biobank). They also assessed whether a causal link existed between cardiovascular risk factors/CHD and depression using Mendelian randomization.
Khandaker and colleagues found that family history of heart disease was linked to 20% greater risk for depression (95% CI, 16-24); however, they did not find a strong connection between the genetic predisposition for CHD and the likelihood of experiencing depression. The results showed that an increase of 1 standard deviation in the heart disease genetic risk score was related to a 71% higher risk for CHD, but only a 1% higher risk for depression (95% CI, 0-3).
Mendelian randomization analyses indicated that the only CHD/cardiovascular risk factor to show evidence of a causal effect on depression risk was triglycerides (OR = 1.18; 95% CI, 1.09-1.27 per standard deviation increase). The inflammatory biomarkers interleukin-6 (OR = 0.74; 95% CI, 0.62-0.89 per unit increase) and C-reactive protein (OR = 1.18; 95% CI, 1.07-1.29 per increase) were also causal risk factors for depression.
"It is possible that heart disease and depression share common underlying biological mechanisms, which manifest as two different conditions in two different organs — the cardiovascular system and the brain," Khandaker said in a press release. "Our work suggests that inflammation could be a shared mechanism for these conditions."
To inform strategies for treatment and prevention, future research should better examine causal risk factors for depression, Khandaker and colleagues explained in the full study.
“Lifestyle modifications targeting ‘inflammogenic’ risk factors such as physical inactivity, obesity, smoking and alcohol use could improve risks for both CHD and depression,” they wrote. “Inflammation is associated with antidepressant resistance, so anti-inflammatory drugs may be helpful for patients with depression who show evidence of immune activation. Anti-cytokine drugs that inhibit IL-6 or TNF-alpha signaling improve depressive symptoms in patients with chronic inflammatory illness, independently of improvement in physical illness.” – by Savannah Demko
Disclosure: The authors report no relevant financial disclosures.