A new study has linked symptoms of depression and anxiety with severity of illness in children with asthma; also uncovering the mechanisms behind the association.
The research was carried out at the University of Buffalo School of Medicine and Biomedical Sciences by Bruce D. Miller, M.D. and Beatrice L. Wood, Ph.D., whose specialities are pediatrics and psychiatry. The primary findings of the study are that depressed children with asthma consistently show a dysregulation of the autonomic nervous system which is associated with increased airway adjustment.
The study is believed to be the first connecting emotional stress, depressive symptoms, autonomic nervous system dysregulation and airway function in childhood asthma.
To give some background information Dr. Miller, Chief of the UB Division of Child & Adolescent Psychiatry and senior psychiatrist at Women & Children's Hospital of Buffalo, explained "The autonomic nervous system, or ANS, is composed of two opposing divisions the sympathetic and parasympathetic nerves, which check one another and thus control critical body functions outside of conscious awareness. The ANS is influenced by stress and emotions."
To go a little further with this, it is worth noting that the sympathetic division is predominantly activated when the body is in a state of arousal. In a stressful situation its activation prepares the body for "fight-or-flight" by increasing the heart rate and breathing rate to provide the muscles and specific organs with oxygen and fuel. The parasympathetic division opposes these actions and is more active during times of relaxation, relaxing muscles and directing activities such as digestiion.
Ninety children with asthma between the ages of 7 and 17 years participated in the study. A comparison was made between forty-five asthmatic children with symptoms of depression and forty-five asthmatic children with no history of depression.
During the study all children viewed the movie E.T. which includes frightening, sad, and happy scenes. To collect data on the childrens' heart and respiratory function, they were required to wear electrodes while viewing the movie so that the researchers could monitor their sympathetic and parasympathetic responses to various stimuli. The research team also evaluated airway function before the movie, after the scene in which E.T. apparently dies, and after the movie.
"The depressed group consistently showed greater parasympathetic activation along with decreased sympathetic activation in response to the emotional provocations; a pattern that would have a detrimental effect on the airways," Miller said.
Adding that, "In contrast, the group without symptoms of depression showed consistent activation of the sympathetic pathway, which would support better airway function under stress. To our knowledge, this is the first report in the literature to demonstrate an association linking stress, depression and increased airway resistance in asthmatic children."
The results of the study also demonstrated that parasympathetic reactivity was most pronounced in children during scenes depicting family distress or loss, death and dying.
These findings reinforce previous results from our laboratory that associated relational stress within the family with child depression and increased asthma activity, says Wood. Although these findings are promising and support our hypotheses. We need further studies to replicate and extend these findings, and to examine whether treatment for depression reduces shift to the parasympathetic and improves lung function in children with asthma.
The authors conclude these findings signify the importance of screening asthmatic children for depressive symptoms.
The study provides intriguing information that could aid the management of asthma from multiple angles. It highlights the importance of happy home and social lives in children with asthma and points to appropriate treatments for depressive symptoms being of potential therapeutic value. Ensuring a healthy home environment is present, encouraging socializing, counseling, and nutritional interventions may all be of value, although only future research can confirm the best approach. Psychoactive drugs (i.e. antidepressants) have repeatedly been shown to be unsafe in children and adolescents.
Source: Miller BD Wood BL Lim J Ballow M Hsu C (2009) Depressed children with asthma evidence increased airway resistance: "vagal bias" as a mechanism? Journal of Allergy and Clinical Immunology 124(1):66-73