The Who, What and Why of Depressive Disorders Part 2

“Some people grumble that roses have thorns; I am grateful that thorns have roses.”

– Alphose Karr


What Causes Depression?

There are many contributing factors to the development of depression. We all have various features that raise our risk, but none independently guarantee a depressive disorder. Once a person starts to feel down, they have a tendency to develop a negative perception, filtering out all positive events. This exacerbates the illness and leads to a self perpetuating cycle where they become more depressed. They may shut themselves off and exhibit behaviors that push others away and worsen their depression. At times, it is obvious to observers that actions such as increased engagement with the world will improve a person’s mood. However, the person suffering is blinded by the illness and is unable to independently take tangible steps to heal.

Biological Model for Depression

Multiple hormones and neurotransmitters are associated with development of depression. 50% of people with severe depression, have abnormal hormones even when not actively depressed. During a depressive episode irregularities are seen in the neurotransmitters serotonin, norpeinephrine, acetylcholine, GABA and glutamate. Many illnesses such as Parkinson’s Disease, abnormal thyroid and cancer can cause depression even before the patient is aware of the condition. Substances such as alcohol, benzodiazepines, marijuana, and opiates have long been known contributors of depression. Furthermore, many medications that are commonly used for high blood pressure, acne, asthma, contraception, smoking cessation or immune disorders have been shown to induce depression. These effects are partially explained by changes in hormone and neurotransmitter levels, but many of the mechanisms are still unexplained.


Brain imaging has shown chronic anatomical changes in people who have suffered from depression. Loss of neurons has been found in the cortex, basal ganglia, thalamus and periventricular regions. During a depressive episode there is less activity in the front left of the brain and increased overall glucose metabolism especially when ruminating on negative events. These effects contribute to recurrent episodes.




If My Parents Have Depression, Will I Have It Too?

There is a strong genetic role in depression. Although a specific gene has not yet been identified, heritabilty is 50%. This means that half the risk of developing depression is attributed to genetic factors. A child of someone with depression has a 2-3 times increased likelihood of developing depression themselves and that doubles when both parents have depression. On the flip side, the majority of people whose parents have depression will not develop a mood disorder.


How Does Stress Impact the Risk of Depression?

Stressful life events often precede a first depressive episode. This can lead to changes in the brain that cause future depressive episodes even when the original stressor is no longer present. The more negatively a person feels that a stressor reflects on their self esteem, the more likely it is to induce a depressive episode. The most significant identified stressful events are losing a parent before the age of 11, or losing a spouse at any age. Those who are unemployed have a 3 times greater risk of developing a depressive disorder. Protective factors include being married, being employed, and affiliating with a religious community.


Does The Way I Was Raised Impact My Risk?

There are multiple psychological theories related to certain childhood environments predisposing to depressive disorders. These surround unmet needs and poor modeling that lead to development of nonconstructive thought patterns and behaviors. Cognitive Theory postulates that depression results from cognitive distortions. more specifically, negative views about oneself, viewing the world as hostile and demanding, and the expectation of future suffering and failure. The theory of learned helplessness explains that early adverse events teach people that they have no control over their environment. This leads to lack of effort and poor social, educational, and occupational functioning with subsequent depressed moods.



The important takeaway is that there are many contributors to depression. When someone is depressed, it is not their fault. Getting out of depression is made more difficult by the affect the illness has on a person’s cognitive processes. It is important to seek help for depression. In the next post we will explore the treatment options.


What do you think? Can you identify any of these contributors in yourself or someone you know. Please post comments and questions below.



Ariel Mintz, MD
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