What causes depression?

At the most basic level, nobody really knows what causes depression. The dominant theory is that it is a result of low levels of certain neurotransmitters (messenger chemicals that carry signals from one nerve cell to the next) in the brain. This is called the ‘monoamine theory’ of depression – monoamines being the group of chemicals that these neurotransmitters belong to.

At the most basic level, nobody really knows what causes depression. The dominant theory is that it is a result of low levels of certain neurotransmitters (messenger chemicals that carry signals from one nerve cell to the next) in the brain. This is called the ‘monoamine theory’ of depression – monoamines being the group of chemicals that these neurotransmitters belong to. The neurotransmitters thought to be involved are serotonin (which helps regulate emotion, sleep and appetite), noradrenaline (which is linked to arousal and alertness), and dopamine (which is associated with pleasure and reward). People with depression are known to have lower brain levels of these chemicals, and drugs that elevate them can help lift mood. So the theory makes sense. But it is not known for sure whether monoamines are the primary cause of depression, or whether other factors are causing both the lowered neurotransmitter levels and the depression. “The brain is such a complex organ,” says Dr Petros Markou. “Lowered amine levels could be the problem, or they could be an indicator of some other problem. What we do know is that raising these levels (using antidepressant drugs) has an effect in 60 to 70 per cent of people.” Who’s at risk? You’re more likely to experience depression if you: have a family history of depression. If someone in your immediate family has depression or bipolar disorder (manic depression), you are two to three times more likely to do so. This may indicate a genetic vulnerability.are female. Women have nearly twice the risk, though the reasons aren’t clear. It’s often been thought that women are more likely to admit or talk about their depression, while men are more likely to use alcohol or drugs to help them cope. But a recent study found that women’s increased rates of depression could largely be attributed to their higher risk of anxiety which in turn, puts them at higher risk of depression. are under stress. Ending a relationship, losing a family member or close friend, or losing a job can trigger depression in some people. Under such circumstances, nearly everyone will, of course, be sad – but not everyone will be depressed. A predisposition to depression, and/or low levels of social support, make some people more vulnerable.are a perfectionist. Certain kinds of perfectionism – not just striving to excel, but having unrealistically high expectations of oneself, being unable to accept fault or failure, and a constant lack of satisfaction, irrespective of performance – have been associated with an increased risk of depression, particularly in the face of work- or school-related stress. have another medical condition such as an under-active thyroid, which can either contribute to depression on its own, or through the stress that comes with being ill. People who’ve had a heart attack, stroke, cancer, or diabetes, for example, have higher than average rates of depression. Some prescription medications can also increase your risk. (Source: ABC, 23 June 2003)