Depressive Disorder

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RISK AND PROGNOSTIC FACTORS

Till date, there is no single causative factor that can be implicated in the development of depression, various genetic, biological (changes in neurotransmitters level) and psycho-social factors interact to play a role in the etiology of the illness, combining in various ways leading to its precipitation.

Genetic Factors: Because depression often runs in families, it appears that a genetic component is involved. Studies have found that close relatives of patients with major depressive disorder have a risk for major depressive disorder two to fourfold more likely to develop the condition than individuals without a family history. Heritability is approximately 40%, and the personality trait neuroticism ac­counts for a substantial portion of this genetic liability.

Biologic Factors: The basic biologic causes of depression are strongly linked to abnormalities in the delivery of certain key neurotransmitters (chemical messengers in the brain). These neurotransmitters include:

- Serotonin. Perhaps the most important neurotransmitter in depression is serotonin. Among other functions, it is important for feelings of well being. An Imbalance in regulation of a neurotransmitter in the brain’s serotonin levels can trigger depression and other mood disorders.

- Other Neurotransmitters. Other neurotransmitters possibly involved in depression include acetylcholine and catecholamines, a group of neurotransmitters that consists of dopamine, norepinephrine, and epinephrine (also called adrenaline).

- Reproductive Hormones. In women, the female hormones estrogen and progesterone may play a role in depression.

Psycho-social factors: Furthermore, many psychological and social stressors like trauma, adverse childhood experiences, loss of a dear one, difficulties in relationships, life-challenges can be a trigger for a depressive episode. Repeated stressful experiences tend to compromise the individual’s ability to cope with the situations as they emerge, which is exacerbated if the individual does not have adequate support mechanisms in the environment.

In addition, various environmental and psycho-social factors could be hypothesized to increase our vulnerability towards depression especially in today’s times, including the hectic lifestyles leading to a neglect of time and space for our own self. With a shifting in family structures, and an increasing dependence on the media and technology, most of us tend to lose out on adequate support systems, leading to social isolation and loneliness. However, it is important to note that these factors are hypothesized to increase the vulnerability towards depression, and are in no way direct causes of depression. In other words, although stressful life events are well recognized as précipitants of major depressive epi­sodes, but the presence or absence of adverse life events near the onset of episodes does not appear to provide a useful guide to prognosis or treatment selection.

Who is at risk for Major Depressive Disorder?

Depressive disorder is not a selective illness; it affects children, teenagers, adults, and senior citizens.Between ten and fifteen percent of the population will have a major depressive episode during their lifetime. The last study conducted in the United States found that the chance of someone having major depression in their lifetime is about one in six (Wolpert, 1999). Some people are at higher risk of depression than others; risk factors include:

- Life events - for example, bereavement, divorce, and poverty

- Personality - less successful coping strategies, for instance

- Genetic factors - first-degree relatives of depressed patients are at higher risk

- Childhood trauma

- Some prescription drugs - including corticosteroids, some beta-blockers, interferon, and reserpine

- Abuse of recreational drugs (including alcohol and amphetamines) - can accompany depression or result in it. There are strong links between drug abuse and depression

- A past head injury

- People who have had an episode of major depression are at higher risk of a subsequent one

- Chronic pain syndromes in particular, but also other chronic conditions, such as diabetes, chronic obstructive pulmonary disease, and cardiovascular disease.

COMORBIDITY

Other disorders with which major depressive disorder frequently co-occurs are substance- related disorders, panic disorder, obsessive-compulsive disorder, anorexia nervosa, buli­ mia nervosa, and borderline personality disorder.

GENDER RELATED-DIAGNOSTIC ISSUES

Although the most reproducible finding in the epidemiology of major depressive disorder has been a higher prevalence in females, there are no clear differences between genders in symptoms, course, treatment response, or functional consequences. In women, the risk for suicide attempts is higher, and the risk for suicide completion is lower. The disparity in suicide rate by gender is not as great among those with depressive disorders as it is in the population as a whole.

Despite consistent differences between genders in prevalence rates for depressive disorders, there appear to be no clear differences by gender in phenomenology, course, or treat­ ment response. Similarly, there are no clear effects of current age on the course or treatment response of major depressive disorder. Some symptom differences exist, though, such that hypersomnia and hyperphagia are more likely in younger individuals, and melancholic symptoms, particularly psychomotor disturbances, are more common in older individuals. The likelihood of suicide attempts lessens in middle and late life, although the risk of com­ pleted suicide does not. Depressions with earlier ages at onset are more familial and more likely to involve personality disturbances. The course of major depressive disorder within individuals does not generally change with aging. Mean times to recovery appear to be sta­ ble over long periods, and the likelihood of being in an episode does not generally increase or decrease with time.

TREATMENT

Depressive disorder is a treatable illness, with many therapeutic options available including psychotherapy, antidepressants, and for more severe cases, electroconvulsive therapy (ECT). In general, the treatment choice depends on