Depression is one of the most commonly talked about mental illnesses, because of which I’m sure we all have a general idea of what it’s about. To put it into simple terms, it is a disorder characterized by prolonged feelings of sadness, worry, guilt, worthlessness or restlessness; and is often accompanied with changes in appetite, libido and loss of interest in activities that were once pleasurable.
The Diagnostic and Statistical Manual of Mental Disorders may help explain depression further. According to this manual which was put together by the American Psychological Association, the broad category of mood disorders (any disorders which have mood disturbances as a predominant feature) come three subheadings, of which depressive disorders (or “unipolar depression”) are one. Under this category, there are three further classifications. These are:
- Major Depressive Disorder – Characterized by at least 2 weeks of depressed mood or loss of interest along with at least 4 symptoms of depression.
- Dysthymic Disorder – Characterized by over 2 years of depressed mood for majority of this time, with signs of depression.
- Depressive Disorder not otherwise classified – Includes those depressive disorders which do not fall under the previously mentioned categories, as well as adjustment or anxiety disorders accompanied with depressed mood.
With a basic idea of what depression is and what it really entails for someone to be diagnosed with a depressive disorder, let’s come to the specifics of it; what actually happens within the body when someone is depressed?
Let’s keep the explanation as simple as possible. For over 4 decades now, scientists have used two words to explain the neurological origin of depression; ‘chemical imbalance’. What they’re referring to is the concentration of certain brain chemicals. It has been found that during major depressive episodes, mood related brain chemicals (neurotransmitters) such as serotonin, norepinephrine and dopamine are low in concentration. At the same time, it has also been found that the enzymes that break down these chemicals are found in higher concentrations. By putting two and two together, they realized that the low concentration of these neurotransmitters (because of their low production or quick break down by enzymes) is directly related to depression. The relative concentrations of these various chemicals and enzymes as well as their transporters thus decide the specific nature of symptoms that an individual would suffer from.
Understanding this chemistry of depression would also explain the working of various types of anti-depressants. While one class of anti-depressants inhibits the functioning of enzymes which break down these brain chemicals responsible for stable moods, others may selectively select which of the chemicals are reused within the brain, thus controlling the amount of these chemicals available in the brain. Based on a person’s individual symptoms and what these say about the state of their mental health, their doctor would prescribe medication as and when they see fit.
References:
- “Mood Disorders”. Diagnostic and Statistical Manual of Mental Disorders: DSM-IV-TR. Washington, DC: American Psychiatric Association, 2000. Pg. 246. Print.
- Nauert, Rick. “Depression’s Chemical Imbalance Explained – Psych Central News.” Psych Central.com. N.p., n.d. Web. 06 July 2014.