Genetic Factors And Depression
Depression can run in families. But having a parent or a sibling with depression doesnt necessarily mean youll have it, too.
If depression runs in your family, you have about a 30% chance of developing it, compared to the typical 10% chance in the general population.
However, recurrent depression may carry a higher genetic risk.
For example, if your parent or sibling has experienced a depressive episode more than once, especially starting earlier in life , your risk may be 4 or 5 times greater than the average persons.
Many people experience more than one depressive episode. Nearly 3 in 4 people with depression will experience a relapse at some point in their lives.
Some disorders, such as cystic fibrosis and sickle cell anemia, are caused by a single gene. But similar to other common genetic conditions like diabetes, depression is not caused by one gene.
Instead, depression is influenced by a complex interplay of genes, biological factors, and environmental causes.
So while depression does run in families, you dont simply inherit this mental health condition from your mom or dad. Your parents contribute certain combinations of genes that can make you more likely to develop the illness.
Other factors such as trauma, substance use, and family environment can also affect your odds.
Clinical Indices Of Familial Aggregation
summarizes data from studies of the clinical indices that predict familial aggregation of major depression . Given the biases possible with clinical ascertainment , it is notable that only a few of these studies were based on community samples . Several of these reports are based on partially or wholly overlapping samples .
Given the diversity of these studies and of the analytic methods used, we are limited to qualitative comparisons. The most widely studied clinical feature is early-onset major depression, although there are two critical conceptual difficulties. First, comparison across studies is problematic, as early onset has been defined in many different ways . Second, only a few studies controlled for confounding between age at onset and age cohort effects for major depression , without which the analyses are difficult to interpret. Among the community-based studies we reviewed, a study of one twin cohort found that age at onset of major depression did not predict familial aggregation , but another twin study found that age at onset was related to increased heritability . Early onset of major depression predicted increased familial risk in four other studies , but not in two others .
If Its Genetic Does That Mean We Can Cure It
Not yet.
Theres no doubt that somewhere out there, right now, researchers are trying to think up ways to end depression forever.
But while theres not yet a cure, treatment is absolutely possible. Treating depression can require both prescribed medication and significant lifestyle changes.
Theres no guarantee we can get rid of the condition permanently, though recurrent depression is common.
According to some research, as many as 50 percent of those who recover from their first depressive episode will go on to have a second.
One day we may fully understand the underlying genetic causes of clinical depression and find a cure. In the meantime, medical treatment and community support are available to help folks living with the condition.
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Common Triggers For Depression
There are as many depression triggers as there are people living with depression. What triggers your depression will be unique to you.
But there are some consistent patterns among people who have depression that make identifying potential triggers a little easier .
Trauma is a common contributing factor to depression. The trauma may come from childhood events or experiences in adulthood. Abuse is a common form of trauma that leads to depression, as are difficult life events like divorce, loss of loved ones, serious illness, or injury.
Reminders of traumatic events can be a trigger for depressive episodes.
Childbirth can also be a depression trigger. According to the CDC, as many as 1 in 5 women may experience depression after giving birth. This is known as postpartum depression.
And its not unique to women 8 to 10 percent of men may also experience baby blues after becoming a parent.
There are many, many other triggers. Illnesses like diabetes and cancer can lead to depression, as can substance misuse. As far as genetic triggers go, a whole bunch of research is happening right now to figure out exactly what they may be.
The Circadian Rhythm Theory
Circadian rhythms oscillate with ~24-h periodicity and are responsible for regulating a wide variety of physiological and behavioral processes. Endogenous cyclic oscillations are regulated in humans and other mammals by the circadian pacemakerthe suprachiasmatic nucleus neurons of the anterior hypothalamus . The circadian pacemaker can change its pattern so that the circadian rhythm may be advanced, delayed, or remain constant in various pathological states or when affected by different pharmacological preparations and hormones for instance, melatonin regulates the function of the biological clock through melatoninergic receptors residing in the hypothalamic SCN . At the cellular level, the molecular clock refers to a network of clock genes, which are transcriptional regulators organized in a feedback-sustained transcriptiontranslation network. This mechanism helps maintain the rhythmic expression of target genes during a 24-h cycle . The basis of the molecular clock is the negative feedback loop, in which the expression of PER and CRY proteins is inhibited by their interactions with the transcriptional factors CLOCK and BMAL1 and by blocking their binding to E-box regulatory elements in the promoters of the genes for PER and CRY protein family members. Posttranslational modifications of the molecular clock system components by signal molecules such as casein kinase / and glycogen synthase kinase 3-beta play important roles in the maintenance of circadian rhythms .
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How Do Genetics Play A Role In Major Depressive Disorder
Scientists have determined the genetic risk factor for major depressive disorder by looking at the patterns of illness in families. This has allowed researchers to understand and estimate the diseases heritability, or roughly what percentage of the disorder is due to genetic factors or other factors. The most reliable prediction of depression as an inheritable disorder have been found through twin studies.
In twin studies, researchers will identify a twin who has been diagnosed with major depressive disorder. An identical twin will share 100% of their genes with their other twin, while non-identical twins share half of their genes. If genes are the most significant cause of depression, then it stands to reason that an identical twin would have a higher risk factor for depression than a non-identical twin with a sibling with the disorder. In twin studies, researchers have found that heritability for depression is somewhere between 40% and 50%.
Adoption studies have also found that an adopted persons risk of depression is more significant if one or both biological parents had depression. The current consensus on parental risk factors is that someone with a parent or non-twin sibling is anywhere between 20% and 30% at risk of developing depression than someone whose parents and siblings do not have the disorder. A person with no known genetic risk factors has about a 10% risk of becoming depressed.
Roots Of Major Depression Revealed In All Their Genetic Complexity
A massive genome-wide association study of genetic and health records of 1.2 million people from four separate data banks has identified 178 gene variants linked to major depression, a disorder that will affect as many as one in every five people during their lifetimes.
The results of the study, led by the U.S. Department of Veterans Affairs researchers at Yale University School of Medicine and University of California-San Diego , may one day help identify people most at risk of depression and related psychiatric disorders and help doctors prescribe drugs best suited to treat the disorder.
The study was published May 27 in the journal Nature Neuroscience.
For the study, the research team analyzed medical records and genomes collected from more than 300,000 participants in the V.A.s Million Veteran Program , one of the largest and most diverse databanks of genetic and medical information in the world.
These new data were combined in a meta-analysis with genetic and health records from the UK Biobank, FinnGen , and results from the consumer genetics company 23andMe. This part of the study included 1.2 million participants. The researchers crosschecked their findings from that analysis with an entirely separate sample of 1.3 million volunteers from 23andMe customers.
When the two sets of data from the different sources were compared, genetic variants linked to depression replicated with statistical significance for most of the markers tested.
Daniel Levey
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Your Chances Of Becoming Depressed
The risk factors that can lead to a diagnosis of major depressive disorder can include:
- Mental health issues in blood relatives. The risk is higher though it is not always possible to know if a diagnosis of depression is truly due to genetics.
- Alcohol and other substance abuse.
- Financial problems.
- The weather. Long, unrelenting winters can causeseasonal affective disorder, which is also known as SAD. This can affect family members or just one person.
Serotonin Transporter And Serotonin Receptor 2a
The serotonin transporter gene and genes involved in the serotonergic system are candidate genes for susceptibility to depression given that many antidepressant medications act on these systems. Several studies have implicated the serotonin transporter gene in MDD . A 44-bp repeat polymorphism in the promoter region of the gene has been shown to influence expression levels of the serotonin transporter in vitro , thus making this functional variant a logical candidate for investigation in MDD. This polymorphism is the most studied genetic variant in psychiatric genetics to date. Similar to candidate gene studies in other complex psychiatric disorders, there have been some positive reports and some negative findings additional studies are needed to dissect the exact role of this gene variant in the etiology of depressive disorders .
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Is Depression Genetic Or Environmental
Yes. No. Maybe?
It depends on who you ask and whose depression youre talking about. There are multiple kinds of depression, and some have stronger ties to genetics than others.
Genetic factors
Science has found some strong links between depression and genetics.
Major depression, or clinical depression, may be as much as five times more likely to occur in people who have relatives with depression than in those who dont.
Heritability rates of major diagnosable depression could be as high as 31 to 40 percent, according to some studies.
Environmental factors
Its also possible to develop clinical depression without any external trigger.
Situational depression is the result of environmental factors. This is the kind of depression many of us experience in the worst moments of life, like getting dumped or losing a job.
So FFS, Greatist, do genetics cause depression or not?!
This question is a massive oversimplification of environmental vs. genetic depression. Theres no simple answer. Clinical depression can develop as a result of untreated situational depression.
A genetic predisposition to low moods could make environmental factors far more likely to trigger depressive episodes. But a loving home can break an intergenerational cycle of parental suicide.
In short, we still dont know 100 percent whether genetics is the be-all and end-all of depression. We do know theres a link in many cases.
Get ready to explore the genetic links and causes of clinical depression.
Major Depression And Genetics
How common is major depression? At least 10% of people in the U.S. will experience major depressive disorder at some point in their lives. Two times as many women as men experience major depression.
How do we know that genes play a role in causing depression? Scientists look at patterns of illness in families to estimate their heritability, or roughly what percentage of their cause is due to genes. To do this we find people with the disease who have a twin, and then find out whether the twin is also ill. Identical twins share 100% of their genes, while non-identical twins share 50% of their genes. If genes are part of the cause, we expect a patients identical twin to have a much higher risk of disease than a patients non-identical twin. That is the case for major depression. Heritability is probably 40-50%, and might be higher for severe depression.
This could mean that in most cases of depression, around 50% of the cause is genetic, and around 50% is unrelated to genes . 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. We dont know the answer yet.
We can also look at adoption studies, to see whether an adopted persons risk of depression is greater if a biological parent had depression. This also seems to be the case.
However, many people who develop major depression did not have this type of personality before their depression started.
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Twin And Family Studies
Evidence for a genetic component to mood disorders has been documented consistently using family, twin, and adoption studies. The first genetic studies of mood disorders were conducted more than 70 years ago and included assessment of concordance rates for monozygotic and dizygotic twins with mood disorders . These early studies did not distinguish between bipolar depression and MDD-recurrent unipolar . A recent review of twin studies in MDD-RU estimated heritability at 37%, with a substantial component of unique individual environmental risk but little shared environmental risk .
Family studies of MDD-RU have shown that first-degree relatives of MDD-RU probands are at increased risk of MDD-RU disorders compared with first-degree relatives of control probands . There was a twofold to fourfold increased risk of MDD-RU among the first-degree relatives of MDD-RU probands. Characteristics of MDD-RU disorders that yield a more heritable phenotype include early onset and a high degree of recurrence. A third characteristic that may identify a separate group of disorders is the presence of psychosis. Additional genetic subtypes of MDD-RU may be identified through examination of comorbidities with panic disorder, other anxiety disorders, and alcoholism.
Study Yields Positive Results On Accurate Medication Dosing
“I do think the results favoring a positive effect on treatment, although small, will encourage providers to test patients and get this genetic information.”
A new VA study found that pharmacogenomic testing can help providers avoid prescribing antidepressant medications that may have undesirable outcomes. Pharmacogenomics is the study of how genes affect the bodys response to drugs.
The researchers also found that the patients who underwent genetic testing had more positive outcomes, compared with patients in usual care. Over 24 weeks of treatment, the group with genetic testing had in a drop in depression symptomswith a peak effect at 12 weeks. Each patient in the study had major depressive disorder. Symptoms of that health condition include insomnia, loss of appetite, feelings of sadness and depression, and thoughts of dying by suicide.
The study results appeared in July 2022 in the Journal of the American Medical Association.
Dr. David Oslin
Dr. David Oslin, director of VAs VISN 4 Mental Illness, Research, Education, and Clinical Center , led the study. He thinks the results will encourage providers to consider using pharmacogenomic testing, with patient consent, to help drive treatment decisions.
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What This Means For The Future Of Treatment
Studying genetics and the environment together will only improve our understanding of depression, better predict risk factors, and help us more effectively treat the illness.
The development of new treatments for depression has been relatively slow, Breen tells us. People have been measuring depression and genetics. Or theyve been measuring depression and environment, but they havent been putting all three things together in one study.It may be that by combining genetic data with environmental data, we can speed that up.
The genetics of depression are complex, adds Sumner. Allowing greater precision in identification in risk and estimates of risk allows improved screening.
With increased study and a better understanding of the genetic, environmental, and genetic-environment correlations, theres hope that in the future well have even better tools for treating one of the worlds most debilitating mental illnesses.
Reviewed On: January 11, 2022
Seeking Treatment For Depression
Mild depression may improve on its own, but if left untreated, symptoms can linger and worsen over time. Most people who treat their depression can recover and regain feelings of happiness and hope for the future. Seeking help is essential, however, especially if your symptoms dont get better. Here are a few simple ways to get started with depression treatment.
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Family Environment And Risk Factors
While many things can factor into the risk of developing depression, researchers found that family environment may play a key role.
According to a Swedish adoption study, family environment could be a protective factor for people who have high-risk genes for major depression.
The study defines a high-quality family environment as one not affected by divorce or parental death before the child turned 15 years old.
Low levels of psychiatric drug or substance use, high educational status, and economic security in the adoptive parents were also considered positive for providing a stable home environment, according to researchers.
Families can come in many different types. A healthy, high-quality family environment can be whatever home environment or family structure that feels most comfortable and right for you and your loved ones.
Researchers looked at a sample of 2,596 half-sibling pairs who had at least one biological parent with major depression, putting them at high risk for major depression. They also looked at more than 660 high-risk full-sibling pairs.
Each sibling pair involved at least one adopted-away sibling and one home-reared sibling.
After controlling for important factors, the researchers found that high-risk half-siblings whod been adopted into healthy family environments were 19% less likely to develop major depression, compared to the home-reared sibling.