This is a complex mental health disorder that affects millions of individuals all across the globe. Life experiences as well as environmental definitely may contribute to the outbreak of the disease, however the biological causes are not negligible. The information towards the biological causes may facilitate scrutiny into more effective treatments and in turn increase understanding of such a crippling condition. This essay details the major biological causes: genetics, brain chemistry, hormonal imbalance, and other major factors that are causing depression.
Genetic Links of Depression
Genetic factors play a very important role in predisposing one to depression. In fact, a number of studies have proven the genetic nature of the disorder. Thus, it is inherited. On a number of occasions, it has been evidenced that depression tends to run in some families. Thus, if one has a first-hand relative who is suffering from depression, his or her chances of becoming depressed also increase.
Key Genes Associated with Depression
Of all genes focused on for the light of major depression, the serotonin transporter gene naturally intensively received the most study. It is involved in trafficking the neurotransmitter serotonin in the brain, and this trafficking is of even more paramount importance in mood regulation. Carrying certain variants of this gene would predispose to depression more than under any stressful condition this would apparently be the cause of it.
Apart from the gene for the serotonin transporter, other genes that are likely to affect the activities of the hypothalamic-pituitary-adrenal axis have been identified; it is through this axis that there is major regulation of the response of an individual to stress. Variants of these genes will, therefore, lead to the excessive activities of the stress response and hence predispose somebody to depression.
Brain chemistry and depression
Neurotransmitters refer to brain chemicals that help transmit signals across nerve cells. An imbalance in these neurotransmitters has been linked to depression. There are three main neurotransmitters that are believed to play a role in depression: these include serotonin, dopamine, and norepinephrine.
Serotonin: The Mood Stabilizer
Serotonin: This “feel-good” chemical functions in the regulation of moods. The basic mechanism of an individual with depression centers on low levels of serotonin. In a deficient state, one would experience more sadness, anxiety, and other symptoms related to sleep disorders. Most of the antidepressants, such as selective serotonin reuptake inhibitors, work on increasing the amount of serotonin in the brain.
Dopamine: The Reward Chemical
Another neurotransmitter very much associated with depression is dopamine. It is part of the reward system in the brain, dealing with feelings of pleasure and motivation. A reduction in dopamine can result in anhedonia, that is, a least ability to experience pleasure in life.
Norepinephrine is a ‘stress hormone’ capable of changing alertness and energy levels. Low quantities of norepinephrine result in high quantities of fatigue and disinterest in patients with depression. This is very common in terms of depressive symptoms. SNRIs, then, adjust the treatment so that they keep into consideration not only the level of the abovementioned serotonin but also the level of norepinephrine in an attempt to positively enhance the level of alertness and focus of patients suffering from depression.
Hormonal Imbalance
Depression can result from hormonal imbalances. The following paragraphs explain in details how major depression results from major imbalances in these hormones.
Cortisol: The Stress Hormone
Cortisol, sometimes referred to as the “stress hormone,” is a hormone the adrenal glands release when one is under stress. In regulation, cortisol is bad for one’s mental health when overproduced continuously. In patients who are currently depressed, ranging from anxiety, to irritability and an inability to concentrate entails some of the symptoms of depression.
Estrogen and Progesterone: Female Hormones and Depression
In women, significant disturbances of mood can easily be associated with hormonal fluctuations. Fluctuations in estrogen and progesterone levels occur during the menstrual cycle, during pregnancy, and at menopause, and may also cause depression. Postpartum depression is considered related to the rapid fall of these hormones post-delivery.
Thyroid Hormones: The Metabolism Regulators
Hormones that regulate metabolic activity are secreted by the thyroid gland. A hyposecretion from this gland results in hypothyroidism, which produces fatigue, slight weight gain, and depression. Mood disturbance may also occur as anxiety and excessive irritability in hyperthyroidism, a condition where the thyroid gland is overactive.
Anatomical and Functional Changes in the Brain in Depression
Advanced neuroimaging techniques, such as functional magnetic resonance imaging and positron emission tomography, have shown the relation of alteration in the structure and function of certain parts of the brain with depression.
The Prefrontal Cortex
The prefrontal cortex thing performs cognitive, problem‐solving, and decision‐making functions; it also helps in checking on and controlling emotions. In general, it has been observed that the prefrontal cortex is underactive in people with depression. This can well explain one of the most common difficulties experienced by them: the inability to concentrate, to make decisions, and to control their emotions.
The Amygdala
The amygdala is a small structure in the brain that is responsible for the processing of emotions. In depressed people, this often becomes overactive; in other cases, the over-activation might be responsible for multiple enhanced emotional responses to stimuli, thus increasing sensitivity to negative events.
The hippocampus is related to processing memory and emotional regulation. Superficially, it is related to depressive patients. To simplify, the hippocampus is smaller in depressed patients. This can help explain memory dysfunction, problems with stress, or both as very common in depression.
The new developments regarding depression come from new research pointing to the fact that inflammation in the body may actually be the linchpin to depression. In most of the people who have depression, the markers for inflammation are usually high. These markers are usually in the forms of C-reactive proteins and cytokines. The chronic inflammation may bring about symptoms such as fatigue, cognitive impairment, and apathy—symptoms that are also some of the standard depression-related symptoms pointing to impairment in the brain.
In other words, it’s a very complex and probably bidirectional relationship—while inflammation may now lead to causes of depressive symptoms; in another way, causes of depression may, in turn, be related to increased inflammation. These factors may form a vicious cycle.
Bidirectional communication between the gastrointestinal tract and the brain takes place via the gut-brain axis. A part of the mental health component resides in the gut, which is called the gut microbiome, consisting of trillions of microorganisms. Furthermore, a connection has been made between bacteria in the gut and depression, where an imbalance in gut bacteria is found, also termed dysbiosis.
It synthesizes neurotransmitters like serotonin on which the body’s immune system is dependent. It is, therefore, extremely critical to maintaining good mental health for the gut microbiome. The population of the various microorganism in the gut can be skewed as a consequence of disturbances and may, overtime give rise to the clinical symptoms of depression. Every attempt, therefore, must be made to optimize gut health.
Conclusion
Depression is a multi-factorial illness with the biological factors as the predisposing genetics, brain biochemistry, and hormonal function. Understanding the roots of such a malady is essential to develop in order to effectively treat them and better the lives of those living with depression. With every new piece of research that illuminates the complex interplay between genetics, brain function, and environmental pressures, new and likely more pointed therapies afford hope to well up.
Awareness of the biology of depression can run realization closer to the individual and effective application of interventions, generally refining the results for a patient with mental diseases.
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