Ventilatory inefficiency in major depressive disorder: a potential adjunct for cardiac risk stratification in depressive disorders?

Physical Health Impairment and Exercise as Medicine in Severe Mental Disorders: A Narrative Review

BACKGROUND

Individuals with severe mental disorders (SMDs; schizophrenia spectrum disorders, bipolar disorder, and major depressive disorder) are not only suffering from their mental conditions; they also have an attenuated physical health, augmenting their overall critical condition.

OBJECTIVES

We review and critically appraise the evidence based on (1) key physiological factors relating to aerobic endurance and skeletal muscle strength; (2) implications for physical function and health; and (3) effects of training interventions with different intensities evaluated in individuals with SMDs.

FINDINGS

Reductions in aerobic endurance factors, peak oxygen uptake (VO_2peak) and walking work efficiency, are paralleled by reductions in maximal skeletal muscle strength and power. In turn, the poor aerobic endurance and muscle strength lead to impaired physical function, increased risk of lifestyle-related diseases, and ultimately early death. Exercise has the potential to counteract the attenuated physical health in people with SMDs. While aerobic endurance training is shown to increase VO_2peak due to plasticity of the oxygen transport system, strength training is documented to improve maximal muscle strength, power, and walking work efficiency as a result of adaptations in neuromuscular force developing factors.

CONCLUSIONS

In conclusion, improvements in these key determinants for physical health appear to be achievable in people with SMDs despite many being challenged by motivational difficulties with attending regular exercise and have beneficial implications for physical function during activities of daily living, lifestyle-related diseases, and early death.

Prevalence and Outcomes of Major Psychiatric Disorders Preceding Index Surgery for Degenerative Thoracic/Lumbar Spine Disease

The relationship between preexisting major psychiatric disorders and outcomes of spine surgery for degenerative thoracic/lumbar disease remains unclear. A 5% subset of inpatients was randomly selected from the Taiwan National Health Insurance Research Database. A total of 10,109 inpatients aged 18 years or over with degenerative thoracic/lumbar disease and underwent spine surgery met inclusion criteria. Major psychiatric disorders diagnosed by psychiatrists preceding index surgery, including anxiety disorder, depression disorder, bipolar disorder, schizophrenia and dementia, were identified. The prevalence of psychiatric disorders, and their differential risks on in-hospital and post-discharge outcomes were examined. 10.4% had major psychiatric disorders, of which depression (6.6%) and anxiety (4.9%) were most common. Logistic regression revealed increased risks of ventilator use in depression (OR = 1.62, 95% CI = 1.04-2.54, p < 0.05), extended hospitalization length in bipolar (OR = 1.77, 95% CI = 1.08-2.89, p < 0.05), and higher rehabilitation utilization in depression (OR = 1.25, 95% CI = 1.06-1.47, p < 0.01) and bipolar (OR = 1.69, 95% CI = 1.04-2.76, p < 0.05). Those patients with anxiety had a decreased risk of longer hospitalization duration (OR = 0.77, 95% CI = 0.60-0.98, p < 0.05), while those with dementia and schizophrenia had no change in risks. Preoperative recognition of major psychiatric disorders for risk and treatment assessment is suggested as people with preexisting depression or bipolar disorder have worse outcomes after spine surgery.

Effects of Endurance Exercise Modalities on Arterial Stiffness in Patients Suffering from Unipolar Depression: A Randomized Controlled Trial

BACKGROUND

Psychiatric disorders are associated with a higher prevalence of cardiovascular disease and mortality. Regular exercise has been shown to reduce depressive symptoms and improve arterial stiffness as a biomarker of cardiovascular risk. We aimed to investigate the effects of different exercise modalities on depression severity index and arterial stiffness in patients suffering from unipolar depression.

METHODS

34 patients suffering from unipolar depression [female: 25, male: 9, age: 37.8, Beck-Depression-Inventory-II (BDI-II) score: 31.0] were enrolled in this two-armed randomized controlled trial. Central hemodynamics, augmentation index at heart rate 75/min (AIx@75) and aortic pulse wave velocity (PWV) were obtained by an oscillometric monitoring device. Maximal bicycle ergometer exercise testing yielded maximal fitness parameters. Patients were assigned to either high-intensity low volume (HILV) or moderate continuous aerobic training (MCT). Both intervention groups trained three times a week during a 4-week intervention period. BDI-II were filled out by the patients before and after the intervention period.

RESULTS

We found moderate interaction effects on depression severity reduction [Formula: see text]. HILV showed a 85% beneficial effect in lowering BDI-II scores compared to MCT (HILV: pre: 28.8 (9.5), post: 15.5 (8.5), SMD = 1.48), MCT: (pre: 33.8 (8.5), post: 22.6 (7.5), SMD = 1.40). Reduction of AIx@75 was more pronounced after MCT (SMD = 0.61) compared to HILV (SMD = 0.08), showing 37% possibly beneficial effects of MCT over HILV. PWV remained unchanged in both training groups.

CONCLUSION

Both training regimes showed large effects on the reduction of depressive symptoms. While HILV was more effective in lowering depression severity, MCT was more effective in additionally lowering peripheral arterial stiffness. Exercise should be considered an important strategy for preventive as well as rehabilitative treatment in depression.

Relationship Between Reverse Remodeling and Cardiopulmonary Exercise Capacity in Heart Failure Patients Undergoing Cardiac Resynchronization Therapy

BACKGROUND

Studies on the relationship between left ventricular reverse remodeling and cardiopulmonary exercise capacity in heart failure patients undergoing cardiac resynchronization therapy (CRT) are scarce and inconclusive.

METHODS AND RESULTS

Eighty-four patients with a 1st-time CRT-defibrillator (mean age 65 ± 11; 73% male) underwent echocardiography and cardiopulmonary exercise testing (CPX) before implantation (baseline) and 6 months after implantation. At baseline, patients also completed a set of questionnaires measuring mental and physical health. The association between echocardiographic response (left ventricular end-systolic volume decrease ≥15%) and a comprehensive set of CPX results was examined. Echocardiographic responders (54%) demonstrated higher peak oxygen consumption and better exercise performance than nonresponders at baseline and at 6-month follow-up. Furthermore, only echocardiographic responders showed improvements in ventilatory efficiency during follow-up. Multivariable repeated measures analyses revealed that, besides reverse remodeling, New York Heart Association functional class II and good patient-reported health status before implantation were the most important correlates of higher average oxygen consumption during exercise, and that nonischemic etiology and smaller pre-implantation QRS width were associated with better ventilatory efficiency over time.

CONCLUSIONS

During the first 6 months of CRT there was a significant positive association between reverse remodeling and cardiopulmonary exercise capacity.

The relation of autonomic function to physical fitness in patients suffering from alcohol dependence

BACKGROUND

Reduced cardio-vascular health has been found in patients suffering from alcohol dependence. Low cardio-respiratory fitness is an independent predictor of cardio-vascular disease.

METHODS

We investigated physical fitness in 22 alcohol-dependent patients 10 days after acute alcohol withdrawal and compared results with matched controls. The standardized 6-min walk test (6 MWT) was used to analyze the relationship of autonomic dysfunction and physical fitness. Ventilatory indices and gas exchanges were assessed using a portable spiroergometric system while heart rate recordings were obtained separately. We calculated walking distance, indices of heart rate variability and efficiency parameters of heart rate and breathing. In addition, levels of exhaled carbon monoxide were measured in all participants to account for differences in smoking behaviour. Multivariate analyses of variance (MANOVA) were performed to investigate differences between patients and controls with regard to autonomic and efficiency parameters.

RESULTS

Patients walked a significantly shorter distance in comparison to healthy subjects during the 6 MWT. Significantly decreased heart rate variability was observed before and after the test in patients when compared to controls, while no such difference was observed during exercise. The efficiency parameters indicated significantly reduced efficiency in physiological regulation when the obtained parameters were normalized to the distance.

DISCUSSION

The 6 MWT is an easily applied instrument to measure physical fitness in alcohol dependent patients. It can also be used during exercise interventions. Reduced physical fitness, as observed in our study, might partly be caused by autonomic dysfunction, leading to less efficient regulation of physiological processes during exercise.

Autonomic modulation in healthy first-degree relatives of patients with major depressive disorder

BACKGROUND

Cardiac mortality is known to be increased in patients with major depression. Several studies have reported an imbalance within the autonomic nervous system (ANS) of patients with major depressive disorder (MDD) as one putative cause. Since a heritability of autonomic modulation was demonstrated in healthy subjects, we aimed to investigate autonomic modulation in first-degree relatives of patients with MDD to find potential autonomic imbalances.

METHODS

We included 30 patients with MDD, 30 of their first-degree relatives (siblings or offspring) and 30 matched healthy controls in our study. We obtained a high resolution electrocardiogram and beat to beat blood pressure measurements for 30 min at rest. Linear and nonlinear parameters of heart rate variability (HRV) and baroreflex sensitivity (BRS) were calculated.

RESULTS

Parameters of HRV and BRS did not differ significantly between relatives and controls. We found significant differences between patients and controls for some HRV and BRS parameters confirming results of previous studies.

DISCUSSION

Findings of our study suggest that an imbalance of autonomic function is related to patients with depression and not to first-degree relatives. Thus, a genetic background for autonomic dysfunction is rather unlikely.

Gender-dependent impact of major depression on autonomic cardiovascular modulation

Depression has been shown to increase the risk for cardiovascular disease (CVD) more strongly in women than in men. Although the underlying mechanisms are unknown, a putative role of increased sympathetic modulation has been suggested for the association of CVD and depression. The aim of this study was to investigate possible gender-associated differences of autonomic function in healthy volunteers and patients suffering from major depressive disorder (MDD). Linear as well as non-linear measures of heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity (BRS) were obtained in each 18 male and 18 female unmedicated patients and respective control subjects. Gender differences were detectable in healthy subjects showing predominant sympathetic modulation in males. This was most obvious in BPV analysis. These gender differences were abolished in patients suffering from MDD, mainly due to altered autonomic modulation in female patients. Our results indicate that BPV is more sensitive to reveal depression-associated changes of autonomic function as compared to HRV. Moreover, female patients contribute most to the overall difference between patients and controls. The shift in the balance of autonomic function in women might account for the increased prevalence of CVD in these patients.