The Scientific American Mind article, “Can nurture save you from your own genes? Genes, environment and depression” introduced by David Dobbs speaks of a scientist’s study of examining two different gene variants and the power of each depending on whether a child is abused, nurtured, or both. The article, “Gene- Environment Interactions: When Nurture Wears a White Hat”, written by Charles Glatt describes the research of fellow scientists Joan Kaufman and Joel Gelernter Nicholas Fayed and colleagues ("Brain-Derived Neurotrophic Factor-5-HTTLPR Gene Interactions and Environmental Modifiers of Depression in Children”).
The ongoing debate of “Nature vs. Nurture” has many theologians, philosophers, and biologists pondering its influence on understanding who we are and what we embody. In the article by Kaufman and Gelernter, they propose that both nature and nurture contribute to who we are; mainly that both genetic factors and environmental factors play a key role in depression. Research has begun to identify genetic risk factors for certain behavioral traits. Some risk factors have been posed in court arguing that punishment for convicted felons should be lessened; the reason being that their genetic predisposition made them acquiesce and made them more prone to misbehave again.
In their paper, Kaufman, Gelernter, and colleagues found clear evidence of gene-environment interactions in the possibility for symptoms of depression. As an alternative to examining single genetic and single environmental factors, this study examines a number of interactions among two genetic factors (nature) and two environmental factors (nurture).
The first most accepted polymorphism (genetic difference between individuals) is in the regulatory region of the gene for the serotonin transporter (5-HTTLPR or serotonin (5-hydroxytryptamine, 5-HT) transporter) polymorphism. This is one of the “nature” factors examined by Kaufman and colleagues. This appears to alter expression of the serotonin transporter molecule. This transporter molecule is also the target of many SSRIs (serotonin-selective reuptake inhibitors) or class of antidepressants.
The second polymorphism is the gene for brain derived neurotrophic factor (BDNF). This is another of the “nature” factors examined by Kaufman and colleagues. This appears to promote the growth of new neurons; particularly brain growth and learning. However, this polymorphism in the BDNF gene alters the efficiency of secretion of BDNF. Many studies have shown that in both animals and humans, decreased levels of BDNF during stress causes depression while SSRIs act to normalize the levels of BDNF.
One “nurture” factor, or environment/experience, aspect looked at as a risk for depression was childhood abuse or maltreatment. In a study, 196 children were scored- 109 children where reports of abuse and/or neglect were present and 87 children (control) where no reports of abuse/maltreatment. Each child was scored for depressive-like symptoms; a high score indicated greater depression. These scores were then compared with combinations of the 5-HTTLPR and BDNF polymorphisms.
Results showed that children with one 5-HTTLPR polymorphism had a higher score only if there were records of childhood maltreatment. Overall, depression was more likely to develop in a child who was neglected and the specific 5-HTTLPR was present. They also found that a certain allele of the BDNF gene increased the effects of the 5-HTTLPR gene, making a child greater susceptible to depression if childhood maltreatment occurred.
Another “nurture” factor aspect looked at as a risk for depression was positive social support. Children were scored again but this time on whether they had high or low social support from the people within their lives. The results showed that having a high social support (nurturing) offset the effects of the genetic risk factors more or less.
The research mainly showed that “genes alone were not likely to make a child depressed, but maltreatment alone could.” In the controversial debate of nature vs. nurture, this study shows that in specific 5-HTTLPR and BDNF polymorphisms: “nurture beats nature.”
I found this article to be very interesting! I have always been interested in clinical research especially disease and disorders. I became interested in depression not too long ago mainly because it is a relatively unknown disorder and there is no single cause for depression. Throughout my research, I found that many factors play a role in depression such as genetics involving inheritability, the environment, medical conditions, life events, and certain thinking patterns that can affect an individual’s reaction to events and predispose them to depression. Most biological research seemed to focus on the role of dysregulation and neurotransmitters involved in depression. These chemicals assist in transmitting messages between nerve cells in the brain. Certain neurotransmitters as we know can regulate mood. When they are not available in sufficient quantities, the result can lead to depression. Overall, depression is a devastating, complex, and highly widespread disorder. It affects individuals of all ages and can be brought about by many different factors. BDNF plays an important role in the maintenance, growth, and the ultimate survival of the brain and peripheral neurons. Any defective regulation or change in the amount of BDNF produced could have severe implications and trigger the onset of depressive symptoms.
I found this article to be significant because throughout my study of BDNF in depression, I never came across studies involving the depression of children in relationship to maltreatment or abuse. This article also opened my eyes to the concept of “nature vs. nurture” and that not all disorders are purely genetic but can be due to one’s environment.
http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=16458264&cmd=showdetailview&indexed=google
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