Genetic predisposition to Depression, an urban myth or a clinical possibility?
Is it possible that our genes make us susceptible to depression?
Written by Thakkarvidhi
What is depression?
Depression is a disorder affecting one’s mood and general outlook. A loss of interest in activities or feeling sad and down are symptoms that characterize this condition. Even though most people feel sad or down for brief periods, clinical depression is more than just feeling sad. It is a serious medical condition and people usually cannot just get over their depressed state.
How does depression affect a person?
Untreated depression can cause lasting issues that include: Employment problems, Strain on relationships, Drug and alcohol abuse, Suicidal thoughts or attempts
Many people who receive effective treatment for depression often go on to live healthy and happy lives. For some, depression may be a lifelong challenge that requires treatment on a long-term basis.
What causes depression?
While several causes can trigger depression, a few of them include the following:
Biochemical causes: Neurotransmitters in the brain — specifically serotonin, dopamine, or norepinephrine — affect feelings of happiness and pleasure and may be out of balance in people with depression. Antidepressants work to balance these neurotransmitters, especially in cases of serotonin imbalance.
Hormonal causes: Changes in hormone production or functioning can also lead to the onset of depressive states. Any changes in hormone states — including menopause, childbirth, thyroid problems, or other disorders — often causes depression.
With postpartum depression, mothers develop symptoms of depression after giving birth. It’s normal to be emotional because of the changing hormones, but postpartum depression poses a serious condition to both the health of the mother and that of the child.
Situational causes: Trauma, a big change, or struggle in life can trigger a case of depression. Losing a loved one, being fired, having financial troubles, or undergoing a serious change can have a big impact on people.
Seasonal causes: As daylight hours get shorter in the winter, many people develop feelings of lethargy, tiredness, and a loss of interest in everyday activities. This condition was called seasonal affective disorder (SAD). Now it’s known as major depressive disorder with seasonal pattern. This condition is treated with medication, talk therapy or photo-therapy, based on the intensity. The condition also usually goes away once the days get longer.
How to identify a case of depression?
While the symptoms of depression can vary depending on the severity, there are some standard symptoms to watch for. Depression not only affects your thought and feelings, it can also impact how you act, what you say, and your relationships with others.
Common symptoms include sadness, tiredness, trouble focusing or concentrating, unhappiness, anger, irritability, frustration, loss of interest in pleasurable or fun activities, sleep issues (too much or too little), no energy, craving unhealthy foods, anxiety, isolation, restlessness, worrying, trouble thinking clearly or making decisions, poor performance at work or school, dropping out of activities, guilt, suicidal thoughts or tendencies, pain, like headaches or muscle aches, drug or alcohol abuse
Some people also show signs of mania, psychotic episodes, or changes in motor abilities.
What are the neurological causes/effects of depression?
Amygdala: The amygdala is part of the limbic system, a group of structures deep in the brain that’s associated with emotions such as anger, pleasure, sorrow, fear, and sexual arousal. The amygdala is activated when a person recalls emotionally charged memories, such as a frightening situation. Activity in the amygdala is higher when a person is sad or clinically depressed. This increased activity continues even after recovery from depression.
Thalamus: The thalamus receives most sensory information and relays it to the appropriate part of the cerebral cortex, which directs high-level functions such as speech, behavioral reactions, movement, thinking, and learning. Some research suggests that bipolar disorder may result from problems in the thalamus, which helps link sensory input to pleasant and unpleasant feelings.
Hippocampus: The hippocampus is part of the limbic system and has a central role in processing long-term memory and recollection. Interplay between the hippocampus and the amygdala might account for the adage “once bitten, twice shy.” It is this part of the brain that registers fear when you are confronted by a barking, aggressive dog, and the memory of such an experience may make you wary of dogs you come across later in life. The hippocampus is smaller in some depressed people, and research suggests that ongoing exposure to stress hormone impairs the growth of nerve cells in this part of the brain.
What role do genes play in depression?
It’s often said that depression results from a chemical imbalance, but that figure of speech doesn’t capture how complex the disease is.
To be sure, chemicals are involved in this process, but it is not a simple matter of one chemical being too low and another too high. Rather, many chemicals are involved, working both inside and outside nerve cells. There are millions, even billions, of chemical reactions that make up the dynamic system that is responsible for your mood, perceptions, and how you experience life.
With this level of complexity, you can see how two people might have similar symptoms of depression, but the problem on the inside, and therefore what treatments will work best, may be entirely different.
Researchers have learned much about the biology of depression. They’ve identified genes that make individuals more vulnerable to low moods and influence how an individual responds to drug therapy.
All parts of the body, including the brain, are controlled and regulated by one’s genes. Genes make proteins that are involved in the various biological processes that make life possible. Throughout life, different genes turn on and off, so that — in the best case — they make the right proteins at the right time. But when incorrect genetic expression takes place, it results in destabilizing one’s mood. In a person who is genetically vulnerable to depression, any stress (a missed deadline at work or a medical illness, for example) can then push this system off balance.
Mood is affected by dozens of genes, and as our genetic endowments differ, so do our depressions. The hope is that as researchers pinpoint the genes involved in mood disorders and better understand their functions, depression treatment can become more individualized and more successful. Patients would receive the best medication for their type of depression.
Another goal of genetic research, of course, is to understand how, exactly, a person’s biology makes them vulnerable to depression. For example, several genes influence the stress response, leaving us more or less likely to become depressed in response to trouble.
Perhaps the easiest way to grasp the power of genetics is to look at families. It is well known that depression and bipolar disorder run in families. The strongest evidence for this comes from the research on bipolar disorder. Half of those with bipolar disorder have a relative with a similar pattern of mood fluctuations. Studies of identical twins, who share a genetic blueprint, show that if one twin has bipolar disorder, the other has a 60% — 80% chance of developing it, too. These numbers don’t apply to fraternal twins, who — like other biological siblings — share only about half of their genes. If one fraternal twin has bipolar disorder, the other has a 20% chance of developing it.
The evidence for other types of depression is more subtle, but it is real. A person who has a first-degree relative who suffered major depression has an increase in risk for the condition of 1.5% to 3% over normal.
An important goal of genetics research is to learn the specific function of each gene and its position (gene-mapping). This kind of information can help figure out how the interaction of biology and environment leads to depression in some people but not others.
Temperament shapes behavior. Genetics provides one perspective on how resilient you are in the face of difficult life events. But one need not be a geneticist to understand that. Perhaps a more intuitive way to look at resilience is by understanding temperament. Temperament — for example, how excitable you are or whether you tend to withdraw from or engage in social situations — is determined by your genetic inheritance and by the experiences you’ve had during the course of your life. Some people are able to make better choices in life once they appreciate their habitual reactions to people and to life events.
Cognitive psychologists point out that one’s view of the world and, in particular, one’s unacknowledged assumptions about how the world works also influences how one feels. A perspective or standpoint is defined early on and provides a fall back method in cases of rejection, failure or stress, etc. For example, some people view themselves as unworthy of love, so they avoid getting involved with people rather than risk losing a relationship. Or in other cases, they may be so self-critical that they can’t bear the slightest criticism from others, which can slow or block their career progress.
Yet while temperament or world view may have a hand in depression, neither is unchangeable. Therapy and medications can shift thoughts and attitudes that have developed over time.
Reference: www.healthline.com
