A depression, if it is not primarily a reaction to a life event, is called in psychiatry a major depressive disorder (MDD). It is a condition characterized by at least two weeks of low mood that is present across most situations. It is often accompanied by low self-esteem, loss of interest in normally enjoyable activities, low energy, and psychological pain without a clear cause. There may also be false beliefs and – in the more severe cases – acoustic or visual hallucinations. Major depression needs to be differentiated from sadness. Depression often actually means the subjective absence of feelings, such as sadness. Those afflicted with depression often cannot feel themselves anymore as before, which can cause additional anxiety.
Major depressive disorder affected approximately 253 million (3.6%) of people in 2013.  The percentage of people who are affected at one point in their life varies from 7% in Japan to 21% in France.  Lifetime rates are higher in the developed world (15%) compared to the developing world (11%).  Depression causes the second most years lived with a disability after low back pain.  The most common time of onset is in a person in their 20s and 30s. Females are affected about twice as often as males.
The many forms of depression
Depression can come in many forms and guises. A mental health professional can help you to identify more closely if you are suffering from depression and form which form. Some ups and downs are a normal part of life. Life does not come in a straight line, which is actually good news, because a straight line would mean that we miss out on the excitement, the feeling alive, that life also offers. However, if the lows, or the highs in those suffering from a bipolar condition, take on intensity or frequency that reduces your quality of life or ability to perform everyday tasks, you should consult a mental health professional.
Melancholia is sometimes seen as a mild form. The cliche image is sitting curled up by a window on a rainy day. Dysthymia is usually the term for episodes of depression that stay just below the clinical threshold. While major forms of depression can occur in one episode or in multiple episodes. Still, however intense it feels, talking to someone about it is usually a good idea, even in milder cases. The view from the outside can be helpful. We may be caught so much by our feeling low that it begins to feel normal. Good indications for depression are not just the feelings one experiences, which in severe forms of depression can be almost absent, but also one’s daily activities and interactions with others. This is where the view from the outside can be helpful. Some people have only one episode of depression in their life, some have episodes of depression separated by years in which they feel normal, while others have symptoms almost constantly. But in all these different forms, from the single case to the recurring depression, treatment is usually effective.
DSM-5 Diagnostic Criteria
The DSM-V, the Diagnostic and Statistical Manual of Mental Disorders in its 5th edition, published by the American Psychiatric Association outlines the following criteria for a diagnosis of depression. The individual must be experiencing five or more symptoms during the same 2-week period and at least one of the symptoms should be either (1) depressed mood or (2) loss of interest or pleasure.
- Depressed mood most of the day, nearly every day.
- Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day.
- Significant weight loss when not dieting or weight gain, or decrease or increase in appetite nearly every day.
- A slowing down of thought and a reduction of physical movement (observable by others, not merely subjective feelings of restlessness or being slowed down).
- Fatigue or loss of energy nearly every day.
- Feelings of worthlessness or excessive or inappropriate guilt nearly every day.
- Diminished ability to think or concentrate, or indecisiveness, nearly every day.
- Recurrent thoughts of death, without a specific plan, or a suicide attempt or a specific plan for committing suicide.
A diagnosis always needs to be carried out by a trained mental health professional.
Another form of depression is reactive depression, which occurs as part of a number of conditions, such as post-traumatic stress disorder (PTSD). I discuss these forms of depression within the articles on these conditions. For PTSD, for example, you may want to look at one of my articles on PTSD:
Suicidal thoughts can be quite common when one feels low or helpless. However, it should always be taken seriously and a mental health professional should be consulted. It does not automatically one has to stay in a hospital. Rather, it should be seen as a sign that something needs to be done quickly to address the mental health condition and raise the quality of life. Between 2-7% of adults with major depression die by suicide  and up to 60% of people who die by suicide had depression or another mood disorder . With the right treatment early enough most of these suicides could have been prevented. Unfortunately, access to healthcare, particularly in the mental health area, is not the same everywhere. But in any case, if you experience suicidal thoughts, you should consult a healthcare professional right away. You can always call and go to an A&E. If none is available quickly, then you should contact a suicide hotline while making arrangements to see a mental health professional in person as soon as possible. Many people have experienced suicidal thoughts in their life, and it can be a strong starting point for very successful therapy.
A Vicious Cycle
Many people with milder forms of depression eventually come out of an episode, either spontaneously or because they have a good support network, are able to manage their stress in life, look after their sleep hygiene, exercise (in healthy moderation), and meditate, for example. However, psychotherapy or counselling is helpful at all levels of depression, and it can help prevent another episode. The problem is that depression can lead to a vicious cycle. The consequences of depression on one’s social life, for example, can make it more difficult to get out of the depression. Major depressive disorder can negatively affect a person’s family, work or school life, sleeping or eating habits, and general health, which distances us from an important resource for better mental health, other people.
The cause is believed to be a combination of genetic, environmental, and psychological factors.  Risk factors include a family history of the condition, major life changes, certain medications, chronic health problems, and substance abuse.   About 40% of the risk appears to be related to genetics. 
Some other common symptoms of depression
Major depression significantly affects a person’s family and personal relationships, work or school life, sleeping and eating habits, and general health.  Its impact on functioning and well-being has been compared to that of other chronic medical conditions such as diabetes. A person having a major depressive episode usually exhibits a very low mood, which pervades all aspects of life, and unhedonia, the inability to experience pleasure in activities that were formerly enjoyed. Depressed people may be preoccupied with, or ruminate over, thoughts and feelings of worthlessness, inappropriate guilt or regret, helplessness, hopelessness, and self-hatred.  In severe cases, depressed people may have symptoms of psychosis. These symptoms include delusions or, less commonly, hallucinations, usually unpleasant.
Other symptoms of depression include
- poor concentration and memory
- withdrawal from social situations and activities
- reduced sex drive, irritability,
- and thoughts of death or suicide (which requires immediate professional help).
Insomnia is a common symptom. In the typical pattern, a person wakes very early and cannot get back to sleep. Hypersomnia, or oversleeping, can also happen. Some antidepressants may also cause insomnia due to their stimulating effect.
A depressed person may report multiple physical symptoms such as
- headaches, or
- digestive problems.
Appetite often decreases, with resulting weight loss, although increased appetite and weight gain occasionally occur. Family and friends may notice that the person’s behavior is either agitated or lethargic.
The biopsychosocial model proposes that biological, psychological, and social factors all play a role in causing depression.
On the biological side, the monoamine hypothesis is still the predominant biological explanation of depression. The monoamines are serotonine, norepinephrine, and dopamine. The antidepressants act on the neurotransmitter levels or on the receptors.
Serotonin is hypothesized to regulate other neurotransmitter systems; decreased serotonin activity may allow these systems to act in unusual and erratic ways. According to this “permissive hypothesis”, depression arises when low serotonin levels promote low levels of norepinephrine, another monoamine neurotransmitter. Some antidepressants enhance the levels of norepinephrine directly, whereas others raise the levels of dopamine, a third monoamine neurotransmitter. These observations gave rise to the monoamine hypothesis of depression. In its contemporary formulation, the monoamine hypothesis postulates that a deficiency of certain neurotransmitters is responsible for the corresponding features of depression.
For further articles on depression on this site:
 “Depression”. NIMH. May 2016.
 American Psychiatric Association (2013), Diagnostic and Statistical Manual of Mental Disorders (5th ed.), Arlington: American Psychiatric Publishing, pp. 160–168, ISBN 978-0-89042-555-8
 Global Burden of Disease Study 2013, Collaborators (22 August 2015). “Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.”. Lancet (London, England). 386 (9995): 743–800. doi:10.1016/S0140-6736(15)60692-4. PMID 26063472.
 Kessler, RC; Bromet, EJ (2013). “The epidemiology of depression across cultures.”. Annual review of public health. 34: 119–38. doi:10.1146/annurev-publhealth-031912-114409. PMC 4100461. PMID 23514317.
 American Psychiatric Association 2000a, p. 349
 American Psychiatric Association 2000a, p. 412
© 2012, 2016 Dr Christian Jonathan Haverkampf. All rights reserved.
Psychotherapy & Counselling, Communication, Medicine (Psychiatry); Dublin, Ireland
This article is solely a basis for academic discussion and no medical advice can be given in this article, nor should anything herein be construed as advice. Always consult a professional if you believe you might suffer from a physical or mental health condition.
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