Quantitative genetic studies not only give an insight. Learn about the depression gene, the serotonin link, and environmental factors that may come into play. One promising avenue for preventing depression and informing its clinical treatment lies in uncovering the genetic and environmental determinants of the disorder. This could mean that in most cases of depression, around 50% of the cause is genetic, and around 50% is unrelated to genes psychological or physical factors. The genetic basis of depression studies, genred and dent, have come close to this sample size and consequently a majority of studies may have been. Although a number of genes have been implicated in depression, a genetic variant that is unequivocally associated with an increased risk of the disease is yet to be identified. Depression is a disorder affecting mood and general outlook. Understanding the genetics of bipolar disorder and other forms of mental illness is an active area of research. Massive study clarifies genetic risks of major depression. According to the world health organization, about 350 million people in the world are affected by this condition. Uncovering the genetic architecture of major depression.
The genetic basis of inbreeding depression genetics. What are the relative contributions of genes and environment. Genetics of depression and major depressive disorder. However, research into the genetics of depression is in its early stages, and very little is known for certain about the genetic basis of the disease. The genetic risk of developing clinical depression is about 40% if a biological parent. It is estimated that 10% to 15% of the general population will experience clinical depression during their lifetime 1, and 5% of men and 9% of women will experience a depressive disorder in a given year, according to the world health organization 2. Bipolar disorder manic depression some people have major mood swings, when periods of depression alternate with periods of mania. Australian genetics of depression study genetics of. Depression is a very common, serious, and misunderstood illness. Kendler2 1wellcome trust centre for human genetics, roosevelt drive, oxford, ox3 7bn 2virginia commonwealth university, department of psychiatry, virginia institute for psychiatric and behavioral genetics, richmond, va 232980126, usa correspondence.
We are now going to have a brief discussion of the many biological, psychological and social factors that have been identified as being related to major depressive disorder. This leaves open the way for a new wave of largescale, genomewide association studies. No single gene is likely to be responsible, but rather a combination of genes. Genetic factors depression often runs in families, which suggests that individuals may inherit genes that make them vulnerable to developing depression. Deleterious mutations probably play a major role in causing inbreeding. The major hurdle that must be overcome in the development of new inbred strains from wild populations is inbreeding depression which occurs most strongly between the f 2 and f 8 generations second through eighth generation of sequential brothersister mating. Genetics play an important part in the development of depression. Is there a genetic relationship between alcoholism and. Major depressive disorder, genetic risk factors, association, linkage, geneenvironment. Bipolar disorder also known as manic depressive illness is a complex genetic disorder in which the core feature is pathological disturbance in mood affect ranging from extreme elation, or mania, to severe depression usually accompanied by disturbances in thinking and behaviour. The genetic basis of inbreeding depression volume 74 issue 3 brian charlesworth, deborah charlesworth. However, one may inherit an increased vulnerability to the illness, but not necessarily the illness itself. In fact, many do not realize that it is classified as a disease.
Depressive disorders dds are one of the most widespread forms of psychiatric pathology. A loss of interest in activities or feeling sad and down are symptoms that characterize this. Based on available data, it is not a single depressive gene that causes depression but is most likely a combination of genes that confers risk, says sumner. Genes that produce moodenhancing neurotransmitters are. Or it could mean that in some cases, the tendency to become depressed is almost completely genetic, and in other cases it is not really genetic at all. Family and twin studies have demonstrated that the contribution of genetic factors to the risk of the onset of dds is quite large.
Depression is one of the most prevalent, disabling, and costly mental health conditions in the united states. Genetic factorsmen with a family history of depression may be more likely to develop it than those whose family members do not have the illness. Biology of depression neurotransmitters depression. The genetics of major depression jonathan flint1, and kenneth s. The genetic basis of inbreeding depression and of the related phenomenon, heterosis, has been a puzzle for many decades. Genetics of depression hodgson major reference works. Frontiers genetics factors in major depression disease. It is estimated that approximately 10% of the population will experience clinical depression at some point in their lifetime, and depression can exist in many forms making it even harder to. In the mid1990s, the life time risk for depression was estimated as 3% to 4% worldwide blazer et al 1994. Hyman1 many of the comfortable and relatively simple models of the nature of mental disorders, their causes and their neural substrates now appear quite frayed. You may have heard that depression is the result of a simple imbalance of brain chemicals.
Studies suggest that nongenetic environmental factors also contribute to a persons risk of developing bipolar disorder. Major depression and genetics genetics of brain function. Major depressive disorder mdd is a common psychiatric illness with high levels of morbidity and mortality. Other factors are known to contribute to the development of all forms of depression and other mental health conditions. The predisposition to develop depression can be inherited. These authors have combined the data from the three largest genetic analyses of depression. Moreover, understanding the genetics of depression may offer a starting point for the development of novel, and potentially more efficacious treatments for patients. The genetics of depression and manicdepressive disorder. As for the specific genetic markers that are definitively linked to depression, thats a little trickier. Based on recent studies in many species, the authors argue that both. The lifetime prevalence of 1% is similar in males and females and family, twin. Despite intensive research during the past several decades, the neurobiological basis and pathophysiology of depressive disorders remain unknown.
Thus, strategies to enhance the genetic homogeneity of mdd samples may be needed to advance our understanding of the genetic basis of depression. It is estimated that 10% to 15% of the general population will experience clinical depression during their lifetime, and 5% of men and 9% of women will experience a depressive disorder in a given year, according to the world health organization. Inbreeding depression an overview sciencedirect topics. Depression is known to run in families, suggesting that genetic factors contribute to the risk of developing this disease.
Depression tends to run in families, suggesting that it is largely hereditary. Major depression is the commonest psychiatric disorder and in the u. Depression is one of the most common mental disorders in the u. Depressive disorders are more common in the relatives of depressed probands than in the population at large, and there is compelling evidence that the familial aggregation of bipolar disorder and severe unipolar depression is at least partly due to genetic factors. Men and depression national institute of mental health.
Family and twin studies have provided strong evidence for the contribution of genetic factors to the risk of depression. Depression can occur along with other serious illnesses, such as diabetes, cancer, heart disease, and parkinsons disease. Genetic factors play important roles in the development of mdd, as indicated by family, twin, and. One promising avenue for preventing depression and informing its clinical treatment lies in uncovering both the genetic and environmental determinants of the disorder as well as their interaction i.
Postnatal depression is a much more serious problem and can occur any time between two weeks and two years after the birth. A deeper understanding of the etiology of depression, including its genetic and environmental determinants as well as their interplay e. Genetic disorders f goes, section editor genetics of depression. Along the way, we identify pertinent open questions that, when addressed, will advance the field. Research suggests that a combination of genetic, biological, environmental, and psychological factors play a role in depression. Webmd explains what research has discovered about the causes of depression from genetics to illnesses and medications to major life events. Major depressive disorder and the neuroticism personality trait have overlapping genetic susceptibilities. In a landmark paper on the genetics of major depression, published in nature genetics 2018, a large consortium of researchers analyzed genetic. Although brain chemicals are certainly part of the cause, this explanation is too simplistic. Understanding the possible causes can help you better understand depression, but remember that depression can also develop in the absence of a clear cause. Genetics of bipolar disorder journal of medical genetics. Even just considering the biological dimension of depression, the brain has multiple layers of complexity. Major depressive disorder, genetic risk factors, association, linkage, gene environment. You may have a higher likelihood of experiencing a depressive disorder at some point in your life if you have a family member with depression.
Genetics is not the only potential cause of depression. Thus, some genetic studies incorporate depressive and anxiety symptoms into a single phenotype, either with trait scores such as neuroticism or. Of the precipitating factors that cause anxiety and depression, chemical imbalances in the brain is a big problem. Preliminary molecular genetic studies performed over the past several decades have implicated only a modest number of specific candidate genes in major depression, thus far offering little insight into its pathophysiological basis. Since the publication of the working draft of the human genome just over a decade ago, there have been dramatic advances in our understanding of the role genetics play in both normal human functioning as well as in disease. Gone is the idea that symptom clusters, course of illness, family history and. Heritability is probably 4050%, and might be higher for severe depression. Pdf major depression is the commonest psychiatric disorder and in the u. Stressful events in a persons life, such as a death in the family, can trigger disease symptoms. Depression can make these conditions worse and vice versa. Overview of the genetics of major depressive disorder. Studies suggest that variations in many genes, each with a small effect, combine to increase the risk of developing. The cause of this depression is the load of deleterious. Studies were identified by searching medline and reference lists of.