• What causes depression?
  • What initiates the alteration in brain chemistry?
  • Is a tendency to depression inherited?
Q. What causes depression?

The group of symptoms which doctors and therapists use to diagnose depression ("depressive symptoms"), which includes the important proviso that the symptoms have manifested for more than a few weeks and that they are interfering with normal life, are the result of an alteration in brain chemistry. This alteration is similar to temporary, normal variations in brain chemistry which can be triggered by illness, stress, frustration, or grief, but it differs in that it is self-sustaining and does not resolve itself upon removal of such triggering events (if any such trigger can be found at all, which is not always the case.)

Instead, the alteration continues, producing depressive symptoms and through those symptoms, enormous new stresses on the person:

  • unhappiness

  • sleep disorders

  • lack of concentration

  • difficulty in doing one's job

  • inability to care for one's physical and emotional needs

  • strain on existing relationships with friends and family.

These new stresses may be sufficient to act as triggers for continuing brain chemistry alteration, or they may simply prevent the resolution of the difficulties which may have triggered the initial alteration, or both.

The depressive brain chemistry alteration seems to be self-limiting in most cases: after one to three years, a more normal chemistry reappears, even without medical treatment. However, if the alteration is profound enough to cause suicidal impulses, a majority of untreated depressed people will in fact attempt suicide, and as many as 17% will eventually succeed. Therefore, depression must be thought of as a potentially fatal illness. Friends and relatives may be deceived by the casual way that profoundly depressed people speak of suicide or self-mutilation. They are not casual because they "don't really mean it"; they are casual because these things seem no worse than the mental pain they are already suffering. Any comment such as, "You'd be better off if I were gone," or "I wish I could just jump out a window," is the equivalent of a sudden high fever; the depressed person must be taken to a professional who can monitor their danger. A formulated plan, such as, "I'm going to jump in front of the next car that comes by," is the equivalent of sudden unconsciousness: an immediate medical emergency which may require hospitalization.

Depression can shut down the survival instinct or temporarily suppress it. Therefore, depressed suicidal thinking is not the same as the suicidal thinking of normal people who have reached a crisis point in their lives. Depressive suicides give less warning, need less time to plan, and are willing to attempt more painful and immediate means, such as jumping out of a moving car. They may also fight the impulse to suicide by compromising on self-injury -- cutting themselves with knives, for example, in an attempt to distract themselves from severe mental pain. Again, relatives and friends are likely to be astonished by how quickly such an impulse can appear and be acted upon.

Q. What initiates the alteration in brain chemistry?

It can be either a psychological or a physical event. On the physical side, a hormonal change may provide the initial trigger: some women dip into depression briefly each month during their premenstrual phase; some find that the hormone balance created by oral contraceptives disposes them to depression; pregnancy, the end of pregnancy, and menopause have also been cited. Men's hormone levels fluctuate as deeply but less obviously.

It is well known that certain chronic illnesses have depression as a frequent consequence: some forms of heart disease, for example, and Parkinsonism. This seems to be the result of a chemical effect rather than a purely psychological one, since other, equally traumatic and serious illnesses don't show the same high risk of depression.

Q. Is a tendency to depression inherited?

It seems there are some people whose brain chemistry is predisposed to the depressive response, and others who are at much lower risk of depression even if exposed to the same physical or psychological triggers. The genetic relations of manic-depressives are at a higher risk for unipolar depression than the population at large or their adopted/by marriage relations. There seems to be a link between high creativity and the gene for manic-depression: artists and writers often are not manic-depressive themselves, but have a family member who is. Studies of families in which members of each generation develop manic-depressive illness found that those with the illness have a somewhat different genetic make-up than those who do not get ill. However, the reverse is not true: not everybody with the genetic make-up that causes vulnerability to manic-depressive illness has the disorder. Apparently additional factors, possibly a stressful environment, are involved in its onset.

Major depression also seems to occur, generation after generation, in some families. However, depression can occur in people with no family history of any form of mental illness. And I would be reluctant to suggest that there is any human who is entirely immune to depression under all possible conditions.

Psychological triggers: many, if not most, people with depression can point to some incident or condition which they believe is responsible for their unhappiness. Of course, people with severe depression are prone to astonishingly virulent and inappropriate guilt and self-hatred.

The (genuine) life events that most often appear in connection with depression are various, but there is one distinguishing feature that appears in many cases, over and over:

loss of self-determination, of empowerment, of self-confidence.

a loss of self, of the abilities or activities that a person identifies with herself.

Stereotypically: a man loses the job that had defined him to himself and others, whether that definition was "executive" or "breadwinner"; a woman who had spent her whole life preparing for and living the role of wife, supporter, caretaker, is suddenly left alone by divorce or death. In general, any life change, often caused by events beyond one's control, which damages the structure that gave life meaning.

The ability of a person to respond to such an event will depend on many factors, including genetic predisposition, support from friends, physical health, even the weather. It can also depend on internal psychological factors which may best be explored in talk therapy: why is the person's self-esteem so bound up in the position or state that has been lost? Can she find a new source of self-esteem? Therapy can be immensely helpful here.

Obviously, not everyone to whom this sort of event happens becomes depressed, and not every person who becomes depressed has had this sort of catastrophe befall them. In fact, if a person suffers a loss and then becomes depressed, it may well be that they weathered the loss in fine style and then succumbed to a much less obvious trigger, psychological or physical. Some depressions may well be caused by a spontaneous aberration in brain chemistry, with no trigger that we can currently identify, just as a seizure or migraine may have an obvious trigger or be apparently spontaneous.

However, once the depressive state has set in, both physical and psychological problems will be generated in abundance. What faster way to lose a job or a spouse than to be too depressed to work or to communicate? What worse psychological state for coping with a blow to identity can there be than a chemically promoted, pathological self-hatred? And what can be worse for self-esteem than watching one's appearance and household disintegrate as one loses the motivation to shower, straighten up, wash dishes or laundry, or choose attractive clothes? Health deteriorates as well: some depressed people can't sleep or eat, others sleep constantly (a real help on the job!) and eat incessantly, sometimes in order to stay awake, sometimes because it's the only thing that gives a little pleasure or comfort. (Carbohydrates induce production of serotonin, so there may be an element of self-medication here); almost no one has the impulse to exercise or get fresh air and sunshine. Most if not all of these effects form feedback loops, increasing in magnitude and becoming triggers for further depression.

The question, "Is depression mostly physical or psychological," is rather beside the point. Depression may be triggered by either physical or psychological events. Most commonly, both seem to be involved, though it is often difficult to separate the two when one is talking about psychology and neurochemistry. But however it begins, depression quickly develops into a set of physical and psychological problems which feed on each other and grow. This is why a combination of physical and psychological intervention has been shown to give the best results for most patients, regardless of any classifications that doctors may have tried to impose on their depression and its cause.

For more information, contact:

Your doctor

Your school / university / private practice counsellor

The Mental Health Unit at the hospital