Introduction: Coronary artery disease (CAD) has been associated with depressive symptoms and deficits in cognitive performance, both of which have been associated with poorer medical prognoses and poorer psychosocial outcomes. Physical activity can improve cognitive and depressive symptoms, and, for those with CAD, improve medical prognoses. It was hypothesized that depressive symptoms and poorer cognitive performance would be associated with poorer cardiopulmonary fitness in patients with CAD, and that these sequelae would be associated prospectively with noncompletion of cardiac rehabilitation (CR). The benefits of physical activity are thought to result, in part, from decreased inflammatory activity and increased adaptive neural plasticity, to which the ratio of kynurenine to tryptophan (K/T) and brain derived neurotrophic factor (BDNF), respectively, in peripheral blood may pertain. Methods and Results: In a cohort study of patients entering CR, depressive symptoms (Center for Epidemiological Studies Depression scale; CES-D scores) were associated with cardiopulmonary fitness (peak volume of oxygen uptake; VO2Peak) during an exercise stress test (B=-.404, p=.001, n=366). The VO2Peak was also associated with performance across multiple cognitive domains, but most strongly with performance on tests involving executive function, attention and psychomotor processing speed (β=.322, p=.002 for composite score, n=81) in a cohort of patients entering CR. In prospective cohort studies, Major Depressive Disorder (adjusted hazard ratio [HR] 2.5, 95% confidence interval [CI] 1.3–4.7, n=195) and poorer performance on a verbal memory test (HR 0.86, 95% CI 0.77-0.96, p=.009, n=131) predicted non-completion of CR. In patients undertaking CR, higher serum K/T ratios were associated with CES-D scores (β=.322, p=.002, n=95) and with VO2Peak (β=-.391, p<.001, n=95), and in a cohort of patients entering CR (n=88), serum concentrations of BDNF were associated with psychomotor processing speed (F1,87=9.620, p=.003), overall cognitive status (Mini Mental Status Exam) scores (F1,87=15.406, p<.0005) and VO2Peak (β=.305, p=.013). Conclusions: Depressive symptoms and poorer cognitive performance are clinically important in patients with CAD entering CR and they are both associated with poorer cardiopulmonary fitness. Poorer cardiopulmonary fitness was also associated with higher K/T ratios and with lower BDNF concentrations in serum, which predicted depressive symptoms and poorer cognitive performance, respectively.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/32324 |
| Date | 26 March 2012 |
| Creators | Swardfager, Walter |
| Contributors | Lanctôt, Krista |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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