Saturday, March 29, 2014
Increased Prevalence of Childhood Asthma
My position is that the increased prevalence of asthma is a result of extrinsic environmental factors that include higher levels of environmental toxins, and intrinsic environmental factors such as the individuals' psychological environment, as well as their diet, level of stress and the health of their immune system. I would not, however, rule out medical practices and more efficient diagnostics as at least minimally contributory to the increase.
An abundance of research as well as traditional wisdom acknowledges environmental triggers or allergens as a cause of asthmatic symptoms (Parker et al., 2008; Priftis, Mantzouranis, & Anthracopoulos, 2009). However, a number of epidemiological studies demonstrate a relationship between diet and asthma. For example, the Mediterranean diet has been associated with a lower prevalence of asthma in school age children (Arvaniti et al., 2011; Batille, Garcia-Aymerich, Barraza-Villarreal, Antó, & Romieu, 2008; Chatzi & Kogevinas, 2009; Garcia-Marcos et al., 2007). This supports the idea that diet may be an important factor in the increase of asthma in children.
Asthma has been referred to as a psychosomatic illness, and stress has been shown to be a factor in its development. In mice, neonatal stress has been shown to permanently alter the immune system of offspring (Vig, Gordon, Thébaud, Befus, & Vliagoftis, 2010). Maternal stress during pregnancy causes changes in the unborn child's immune system (Wright, 2012). In particular, prenatal stress alters the child's antigen response, which is an underlying issue in asthma. Wright (2011) postulated "biological, psychological, and social processes interact throughout the life course to influence disease expression" (p. 1), and that stress, especially psychosocial stress in early life, contribute to lung diseases, such as asthma. The idea of psychological stress and the epigenetic mechanisms of gene expression as contributory in the development of asthma should not be overlooked. Perhaps children are under increased stress which would contribute to the increase in childhood asthma.
Regarding the immune response and the immune system in general, Marshall and Agarwal (2000) found that chronic psychological stress is associated with the proliferation of hyperactive cytokines, which creates cell mediated immune responses. Stress does not simply suppress the immune system, but alters it in a way that creates the inflammatory environment that is characteristic of allergic reactions and asthma (Marshall & Agarwal, 2000). This, of course, is not a process that takes place in every individual under stress, but these immune imbalances may favor an inflammatory response, such as asthma, in susceptible individuals. It may be possible that modern day living puts additional stress on the immune system, or causes its dysfunction, which may lead to an increase in childhood asthma.
Although the exact underlying mechanisms of the onset of asthma remain unclear, it has been well-established that cytokines and immune cells play a central role in the onset of asthma (Zhang et al., 2013). This lack of clarity as well as the individual variables in triggers, symptom severity, and effective treatments make asthma a challenging, albeit common childhood illness.
Arvaniti, F., Priftis, K., Papadimitriou, A., Papadopoulos, M., Roma, E., Kapsokefalou, M., & ... Panagiotakos, D. (2011). Adherence to the Mediterranean type of diet is associated with lower prevalence of asthma symptoms, among 10-12 years old children: the PANACEA study. Pediatric Allergy And Immunology: Official Publication Of The European Society Of Pediatric Allergy And Immunology, 22(3), 283-289. doi:10.1111/j.1399-3038.2010.01113.x
Batlle, J. D., Garcia-Aymerich, J., Barraza-Villarreal, A., Antó, J. M., & Romieu, I. (2008). Mediterranean diet is associated with reduced asthma and rhinitis in Mexican children. Allergy, 63(10), 1310-1316. doi: 10.1111/j.1398-9995.2008.01722.x
Chatzi, L., & Kogevinas, M. (2009). Prenatal and childhood Mediterranean diet and the development of asthma and allergies in children. Public Health Nutrition, 12(9A), 1629. doi: 10.1017/S1368980009990474
Garcia-Marcos, L., Canflanca I. M., Garrido, J.B., Varela, A. L., Garcia-Hernandez, G., Guillen Grima, F., ...Blanco-Quiros, A. Relationship of asthma and rhinoconjunctivities with obesity, exercise and mediaterranean diet in Spanish schoolchildren. (2007). Thorax, 62(6), 503-8.
Laureate Education, Inc. (Executive Producer). (2012). Child and adolescent health: Living with asthma. Baltimore, MD: Author.
Marshall, G., & Agarwal, S. (2000). Stress, immune regulation, and immunity: applications for asthma. Allergy And Asthma Proceedings: The Official Journal Of Regional And State Allergy Societies, 21(4), 241-246.
Priftis, K. N., Mantzouranis, E. C., & Anthracopoulos, M. B. (2009). Asthma symptoms and airway narrowing in children growing up in an urban versus rural environment. Journal of Asthma, 46(3), 244–251.
Vig, R., Gordon, J., Thébaud, B., Befus, A., & Vliagoftis, H. (2010). The effect of early-life stress on airway inflammation in adult mice. Neuroimmunomodulation, 17(4), 229-239. doi:10.1159/000290039
Wright, R. (2011). Epidemiology of stress and asthma: from constricting communities and fragile families to epigenetics. Immunology & Allergy Clinics Of North America, 31(1), 19-39. doi:10.1016/j.iac.2010.09.011
Zhang, Y., Luan, B., Wang, X., Qiao, J., Song, L., Lei, R., & ... Liu, Y. (2013). Peripheral Blood MDSCs, IL-10 and IL-12 in Children with Asthma and Their Importance in Asthma Development. Plos ONE, 8(5), 1-9. doi:10.1371/journal.pone.0063775