BACKGROUND:
Classic risk factors for coronary heart disease (CHD) do not yet predict the majority of new
cases. Of the novel risk factors recently explored, elevated depressive symptoms have been
found in a number of prospective studies to predict new CHD cases, as have inflammatory
markers, including high sensitivity C-Reactive Protein (CRP), interleukin-6 (IL-6), and
intercellular adhesion molecule. Interestingly, depression and inflammatory markers have high
covariation, and intervention studies indicate that reducing depression may reduce peripheral
inflammation, while successfully treating inflammation may ameliorate depressive symptoms. It
becomes critical then to know if these candidate CHD risk factors are independent or
dependent of the other in the prediction of CHD incidence.
DESIGN NARRATIVE:
The study will determine if depressive symptoms and inflammatory markers are independent or
dependent CHD risk factors, when controlling for the other known CAD risk factors. A
population-based prospective study (the Nova Scotia Health Survey; NSHS95) was conducted
almost 10 years ago, in which participants were randomly selected from the socialized medical
registry, which includes all citizens. All classic CHD risk factors were obtained at baseline
(age, sex, race, fasting lipids, diabetic status, family CHD history, resting blood pressure,
exercise levels, body mass index, smoking status, and socioeconomic status). Depressive
symptoms as assessed by the Center for Epidemiological Studies Depression scale were also
obtained at baseline. Plasma blood samples were obtained and maintained in a -80 degree
(Celsius) freezer. Participants gave permission for medical registry records to be linked to
their survey data, so that objectively documented previous and future CAD events could be
detected. The study will assay plasma samples for CRP, IL-6 and ICAM-1 and then statistically
model the associations among depression, inflammation and CHD incidence.
