The human brain has developed a mechanism that increases its resilience to depression called the transcription factor for DeltaFosB. If this system does not work, an individual becomes depressed, according to researchers reporting in the May 2010 issue of Natural Neuroscience. Another team from Harvard University found abnormal mitochondrial energy metabolism in bipolar disorder, evidence that bipolar disorder, too, is a physiologically based disorder.
Causes of Depression
Since depression decreases functionality, the body has developed several systems to protect the mood. The discovery of one of these protective mechanisms, DeltaFosB, has increased understanding of why resilience to life stressors is easier for some individuals than for others. If a child is born with a high degree of chemically supported resilience to depression, he is able to tolerate frustrations and disappointments without losing hope when facing a crisis.
But other physical factors are also known to induce depression. The lack of exposure to sufficient sunlight, nutrient deficiencies, fibromyalgia, multiple sclerosis, epilepsy, brain injury and chronic pain syndromes are among those most commonly cited.
With the higher incidence of chronic diseases associated with obesity, namely, diabetes, hypertension and arthritis, an increase in depression is expected, and since children are becoming obese at an epidemic rate, the concern is that these same factors may increase their rates of serious depression within a few years.
One physical explanation for an increase in childhood depression is the elevated levels of the stress hormone cortisol that obese children and teens exhibit. At the 2009 meeting of the Endocrine Society, Panagiota Pervanidou, M.D., reported her findings that "the more depressive symptoms that subjects reported, the higher the cortisol level."
Causes of Bipolar Disorder
Christine Konradi, Ph.D., of the Mailman Center in Massachusetts, working with a team at Harvard, reports the discovery of decreased mitochondrial activity in the hippocampus of individuals with bipolar disorder that cannot be otherwise explained.
A strong genetic factor in bipolar disorder has previously been proven in twin and adoption studies, as reviewed by Dr. Jordon Smoller in the 2003 edition of the American Journal of Medical Genetics. Having one relative with bipolar disorder "Increases the risk of developing the disease tenfold" Smoller states.
With this strong genetic predisposition, is there any way to avoid bipolar disorder? The answer is "maybe." Children with anxiety disorders or an episode of severe and prolonged depression, often related to the death of a parent, have a higher-than-expected risk of developing adult onset bipolar disorder. Early treatment of these disorders appears to lower the risk significantly, according to the National Institutes of Mental Health.
In addition, diabetes is diagnosed three times more frequently in people with bipolar disorder. A diet low in carbohydrates and high in alpha-omega-3 fatty acids has been shown to decrease the severity, if not the incidence of bipolar disorder, and the diet is also associated with a low risk of diabetes.
Social Causes of Mood Disorders
Depression and bipolar disorder are not new. But changes in family structures and work environments may lead to both increased severity of the symptoms and an increased incidence of diagnosable levels of disease. Stability leads to predictability, especially for children. In a predictable environment with little change over time, the growing mind has less stimulus for anxiety, which is considered a precursor to bipolar disorder, and may also have greater resilience to depression. Chaotic home lives, where the members of the family change frequently due to divorce, remarriage, deployment, death or incarceration are known risk factors for the development of depression and anxiety disorders, according to the American Pediatric Association.
A study reported in the December 2003 issue of the American Journal of Psychiatry found that "a chaotic family environment in adolescence was the most important factor in predicting depression during the transition to adulthood."
These findings point to the benefits for all children, but especially for those at risk of depression or bipolar disorder, to move through childhood and adolescents in a stable, emotionally and physically safe home environment.
References
- PubMed.gov: Natural Neuroscience; DeltaFosB in Brain Reward Circuits Mediates Resilience to Stress and Antidepressant Responses; V. Vialou, et al.; May 16, 2010
- "Archives of General Psychiatry"; Christine Konradi, Ph.D., Molly Eaton, B.A., Matthew L. MacDonald, B.S., John Walsh, M.S., Francine M. Benes, M.D., Ph.D., Stephan Heckers, M.D.
- Health.am: The Endocrine Society's 91st Annual Meeting in Washington, D.C.; Symptoms of Depression in Obese Children Linked to Elevated Cortisol; Panagiota Pervanidou, M.D., et al.; June 2009
- American Journal of Medical Genetics; Family, Twin and Adoption Studies; Jordon Smoller and Christine Finn; 2003
- American Journal of Psychiatry; Childhood and Adolescent Predictors of Major Depression in the Transition to Adulthood; Helen Z. Reinherz, Sc.D., et al.; December 2003
