Antidepressants are psychiatric medications given to patients with depressive disorders to alleviate symptoms. They correct chemical imbalances of neurotransmitters in the brain which probably cause changes in mood and behavior.
Antidepressants were initially developed in the 1950s. Their use has become progressively more common over the last twenty years.
Antidepressant usage is increasing
In 1996 there were 13.3 million people using antidepressants in the United States. By 2010, the figure stood at 23.3 million people. Researchers from Columbia University Medical Center, the New York State Psychiatric Institute, and the University of Pennsylvania added that rates remained low among racial and ethnic minorities.
They believe antidepressant usage has become more common because:
- There has been a broadening in the concepts of need for mental health treatment
- Campaigns to promote mental health care have become more widespread
- Mental health treatments have become more widely accepted by the public
According to data gathered from public health authorities in Canada, Western Europe and Australasia, increased antidepressant usage has been a progressively common trend in most industrialized countries.
How do antidepressants work?
This YouTube video by Paul Bogdan explains how antidepressants work.
Types of antidepressants
According to the Royal College of Psychiatrists2, England, there are nearly thirty different kinds of antidepressants, which can be divided into five main types:
1) Monoamine oxidase inhibitors (MAOIs)
Also known as monoamine oxidase inhibitors, are a kind of antidepressant that inhibit the action of monoamine oxidase, a brain enzyme. Monoamine oxidase helps break down neurotransmitters, such as serotonin.
If less serotonin is broken down, the patient hopefully has more stabilized moods and less anxiety. Doctors usually use MAOIs if SSRIs have not worked, because MAOIs clash with a considerable number of other medications and some foods.
MAOIs have the following possible side effects: blurred vision, rash, seizures, edema, weight loss, weight gain, sexual dysfunction, diarrhea, nausea, constipation, anxiety, insomnia, drowsiness, headache, dizziness, arrhythmia, fainting, feeling faint when standing up (postural hypotension), and hypertension.
Examples of Monoamine Oxidase Inhibitors are: phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan) and selegiline (EMSAM, Eldepryl).
2) Noradrenaline and Specific Serotoninergic Antidepressants (NASSAs)
These are a class of compounds which are used in the treatment of anxiety disorders, some personality disorders, and depression.
NASSAs have the following possible side effects: constipation, dry mouth, weight gain, drowsiness, sedation, blurred vision and dizziness. More serious adverse reactions include: seizures, white blood cell reduction, fainting, and allergic reactions.
Examples of Noradrenaline and Specific Serotoninergic Antidepressants include: Mianserin (Tolvon) and Mirtazapine (Remeron, Avanza, Zispin)
3) Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs)
SNRIs are a class of drugs used to treat major depression, mood disorders, and possibly but less commonly ADHD (attention deficit hyperactivity disorder), obsessive compulsive disorder, anxiety disorders, menopausal symptoms, fibromyalgia, and chronic neuropathic pain.
SNRIs raise levels of serotonin and norepinephrine, two neurotransmitters in the brain - they both play a key role in stabilizing mood. (See below in side effects for SSRIs, which are very similar)
Examples of Serotonin Norepinephrine Reuptake Inhibitors are: duloxetine (Cymbalta), venlafaxine (Effexor) and desvenlafaxine (Pristiq).
4) Selective Serotonin Reuptake Inhibitors (SSRIs)
Prozac (fluoxetine) is probably the most widely known antidepressant worldwide among lay people.
SSRIs are the most commonly prescribed antidepressants. Experts say that SSRIs are not only very effective in treating depression; they also have fewer side-effects than the other types.
SSRIs block the reuptake (absorption) of serotonin in the brain, thus helping the brain cells receive and send messages, which results in better and more stable moods. They are called "selective" because they seem to mainly affect serotonin, and not the other neurotransmitters.
SSRIs and SNRIs may have the following side effects: hypoglycemia, low sodium, nausea, rash, dry mouth, constipation, diarrhea, weight loss, sweating, tremor, sedation, sexual dysfunction, insomnia, headache, dizziness, anxiety, agitation, and abnormal thinking.
Examples of SSRI antidepressants are: citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac, Sarafem), fluvoxamine (Luvox), paroxetine (Paxil) and sertraline (Zoloft)
Tricyclics are so named because there are three rings in the chemical structure of these medications. This class of medication is used to treat depression, and also some types of anxiety, fibromyalgia, and to control chronic pain.
Tricyclics may have the following side effects: seizures, insomnia, anxiety, arrhythmia, hypertension, rash, nausea, vomiting, abdominal cramps, weight loss, constipation, urinary retention, increased pressure on the eye, and sexual dysfunction.
Examples of tricyclic antidepressants are: amitriptyline (Elavil), amoxapine- clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), imipramine (Tofranil), nortriptyline (Pamelor), protriptyline (Vivactil) and trimipramine (Surmontil)
Antidepressants are not all the same
How the antidepressants affect neurotransmitters, how they are used, and what adverse effects or drug interactions are associated with them differ. One patient may not respond to one type of antidepressant and do better with another, while another person with a similar condition might respond the other way round.
On the next page we look at how long antidepressants take to work, the conditions that they are used to treat and how effective antidepressants are. On the final page we discuss whether you can become addicted to them, the issues with pregnancy and breast feeding, defining the length of antidepressant treatment and how you can reduce the risk of depression coming back.