ABSTRACT
BACKGROUND: Depression is known to be associated with altered cardiovascular variability and increased cardiovascular comorbidity, yet it is unknown whether altered cardiac autonomic function in depression is associated with insomnia, a common symptom comorbid with depression. This study aimed to investigate the long-term diurnal profile of autonomic function as measured by heart rate variability (HRV) in both major depression and primary insomnia patients. METHOD: A total of 52 non-medicated patients with major depression, 47 non-medicated patients with primary insomnia, and 88 matched controls without insomnia were recruited. Each subject was assessed by means of sleep and mood questionnaires and underwent twenty-four-hour ambulatory electrocardiogram monitoring. Standard HRV analysis and a well-validated complexity measure, multiscale entropy, were applied to comprehensively assess the diurnal profiles of autonomic function and physiologic complexity in our study sample. RESULTS: Compared with the controls, the patients with major depression and those with primary insomnia exhibited significant reductions in parasympathetic-related HRV indices, and this association was mainly driven by the presence of poor sleep. Both groups of patients also exhibited significant reductions in physiologic complexity during the sleep period as compared with the healthy controls. Alterations in HRV indices were correlated with perceived sleep questionnaire scores but not with depression scales. CONCLUSIONS: Our findings suggest a pivotal role of sleep disturbance in regulating cardiovascular variability in major depression and primary insomnia patients. These findings could highlight the importance of treating insomnia as an independent disease rather than a symptom.
Subject(s)
Depressive Disorder, Major/complications , Sleep Initiation and Maintenance Disorders/complications , Adult , Chi-Square Distribution , Circadian Rhythm/physiology , Depressive Disorder, Major/physiopathology , Electrocardiography , Female , Heart Rate/physiology , Humans , Linear Models , Male , Middle Aged , Monitoring, Physiologic , Psychiatric Status Rating Scales , Sleep Initiation and Maintenance Disorders/physiopathology , Sleep Initiation and Maintenance Disorders/psychology , Surveys and Questionnaires , Young AdultABSTRACT
Sleep disruption is an important aspect of major depressive disorder but lacks an objective and inexpensive means of assessment. We evaluated the utility of electrocardiogram (ECG)-based cardiopulmonary coupling analysis to quantify physiologic sleep stability in patients with major depression. Relative to controls, unmedicated depressed patients had a reduction in high-frequency coupling, an index of stable sleep, an increase in low-frequency coupling, an index of unstable sleep, and an increase in very-low-frequency coupling, an index of wakefulness/REM sleep. The medicated depressed group showed a restoration of stable sleep to a level comparable with that of the control group. ECG-based cardiopulmonary coupling analysis may provide a simple, cost-efficient point-of-care method to quantify sleep quality/stability and to objectively evaluate the severity of insomnia in patients with major depression.
Subject(s)
Depressive Disorder, Major/physiopathology , Electrocardiography, Ambulatory/methods , Heart Rate/physiology , Respiration , Sleep Initiation and Maintenance Disorders/diagnosis , Sleep/physiology , Adult , Depressive Disorder, Major/complications , Female , Humans , Male , Middle Aged , Sleep Initiation and Maintenance Disorders/etiologyABSTRACT
A common polymorphism of the brain-derived neurotrophic factor (BDNF) gene (Val66Met) has been implicated in anxiety, which is associated with lower vagal activity. We hypothesize that the BDNF Val66Met polymorphism may have a modulatory effect on the cardiac sympathovagal balance. A total of 211 healthy Chinese-Han adults (58 male, 153 female, aged 33.3 +/- 10.3 years) were recruited with three BDNF genotypes: Val/Val (47, 22.3%), Val/Met (108, 51.2%), and Met/Met (56, 26.5%). Autonomic function was assessed via an analysis of heart rate variability. Reductions in high-frequency power, an index for parasympathetic activity, and increases in the low-frequency/high-frequency ratio, an index for sympathovagal balance, were found in subjects bearing the Met/Met genotype as compared to the Val/Val group. These results suggest that an altered sympathovagal balance with relatively decreased parasympathetic activity is associated with the Met/Met genotype, suggesting a potential role for the studied BDNF polymorphism in modulating cardiac autonomic functions.
