Trillian's Depression Page
All people experience periods of sadness. Usually these last for only one to
several hours or days. Often the cause of this lowered mood is obvious;
sometimes it occurs for no reason. Some people experience more prolonged
periods of sadness following the loss of a friend or family member. This is
usually described as grief or bereavement. A depressive illness is a persistent
lowering of mood lasting for several weeks at a time, and accompanied by a
specific group of physical and psychological symptoms. This may cause serious
physical, psychological and social problems, and requires specific treatment.
Any of the following may be part of a depressive illness:
 feeling sad, crying easily
sleep disturbance
changes in appetite and weight
loss of interest and motivation
loss of energy and becoming easily fatigued
physical aches and pains, especially headache or abdominal pain
loss of sexual interest, impotence
feeling that life is not worth living
feelings of helplessness
guilt, and self reproachful thoughts
pessimism regarding the future
irritability
anxiety
confusion, poor memory
alcohol or drug abuse
Major depression is a one-episode illness for about half the people who
suffer from it, but for the other half, it is a recurring illness. For most
people with recurrent depression, the symptoms disappear completely between
episodes but for a third of people with depression, there are lingering
symptoms between episodes.
Although about 25% of all individuals experience some form of affective
disturbance, the lifetime risk for clinically identifiable mood disorder is 8
to 9%. One third develop a chronic course and, of the remaining 5 to 6%, at
least 2/3 experience recurrent episodes. This means that for most sufferers,
the illness will recur or pursue a protracted course. The rates are higher in
women in a 2:1 ratio for the predominantly depressive forms of illness, and
nearly even in bipolar disorder.
Bipolar conditions, for which 1% of the population is at risk, usually begin
in the teens, 20s, and 30s; unipolar conditions begin, on average, a decade
later than their bipolar counterparts. Recent epidemiologic findings in the USA
suggest a cohort effect, whereby those born in the latter part of this century
have higher rates of depression and suicide, often associated with higher rates
of substance abuse. Although some of this increase is probably due to easier
ascertainment of depression in younger individuals, the comorbid substance
abuse and poorly understood environmental factors may have contributed to the
younger age shift.
Depression is among the most prevalent psychiatric conditions,
varying from about 25% in public mental institutions to nearly 50% in
outpatient and private psychiatric practice, and it may account for as much as
10% of all patients seen in non psychiatric medical settings. Culture, social
class, and race have not been shown to make significant differential
contributions to the incidence of mood disorders. However, sociocultural
factors seem to modify the clinical manifestations; e.g., somatic complaints,
worry, tension, and irritability are more common in the lower socioeconomic
classes; guilty ruminations and self-reproach are more characteristic of
depressions in Anglo-Saxon cultures; and in some Mediterranean and African
countries, as well as in American blacks, mania tends to manifest itself more
floridly.
Major depression can have many causes. Psychological factors that increase
the risk of depression include difficulty expressing anger effectively,
experiencing losses, poor self-esteem, strong dependency needs, poor
interpersonal skills and a pessimistic view of oneself and the world.
Genetic inheritance is an important factor for many people, as is a high
level of stress.
In recent years, it has become abundantly clear that depression also
involves a very specific chemical imbalance in the areas of the brain that are
responsible for mood and emotion.
A recent study of adult twins and their families suggests that depressive
symptoms are influenced modestly by heredity and hardly at all by common
childhood environment. One group of twins, with an average age of 60, was
recruited with the help of the American Association of Retired People; another
group, with an average age of 30, was drawn from the Virginia Twin Registry.
About 15,000 twins and 15,000 members of their families answered a mailed
questionnaire, rating themselves for typical depressive symptoms (such as
sadness, physical complaints, apathy, and insomnia). Scores on this
questionnaire were known to be highly correlated with a standard test for
clinical depression, a psychiatric diagnosis of major depression, and a risk of
future depression.
The correlation for depressive symptoms was highest among identical twins.
It indicated a heritability (proportion of the variance, or individual
differences, explained by heredity) of 37% in the AARP and 30% in the Virginia
Twin Registry group. The correlation among fraternal twins was about half as
strong. Heritability estimates based on twins alone were confirmed by the
responses of other genetically related family members. The results for
genetically unrelated family members were also revealing. In-laws were entirely
uncorrelated for depressive symptoms, but husbands and wives were about as
highly correlated as fraternal twins. Since this similarity did not become
greater with more years of marriage, the authors believe it resulted not from
mutual influence but from assortative mating-the tendency to marry someone
similar to oneself. A smaller sample of 4,500 twins answered the questionnaire
again 14 months later. When both sets of answers were counted, heritability
rose to 56% in the AARP group of twins and 52% in the Twin Registry group. That
is, symptoms appeared more highly heritable when they persisted and therefore
implied a stable predisposition or temperament.
By contrast, childhood environment apparently contributed nothing to
individual variation. Despite the large number of people studied and the
variety of family relationships, there was no evidence that having grown up at
the same time in the same home with the same parents, having lived in the same
neighborhood, or having attended the same schools caused adults to report
similar symptoms of depression. Whatever effects parents, school, and
neighborhoods may have had, they were either quite different in different
children of the same family or did not persist until the children grew up.
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