contrast to the normal emotional experiences of sadness,
loss, or passing mood states, clinical depression is persistent
and can interfere significantly with an individual's ability
to function. There are three main types of depressive disorders:
major depressive disorder, dysthymic disorder, and bipolar
disorder (manic-depressive illness).
and Types of Depression
Symptoms of depression include sad mood, loss of interest
or pleasure in activities that were once enjoyed, change
in appetite or weight, difficulty sleeping or oversleeping,
physical slowing or agitation, energy loss, feelings of
worthlessness or inappropriate guilt, difficulty thinking
or concentrating, and recurrent thoughts of death or suicide.
A diagnosis of major depressive disorder is made if a person
has 5 or more of these symptoms and impairment in usual
functioning nearly every day during the same two-week period.
Major depression often begins between ages 15 to 30 but
also can appear in children. Episodes typically recur.
people have a chronic but less severe form of depression,
called dysthymic disorder, which is diagnosed when depressed
mood persists for at least 2 years (1 year in children)
and is accompanied by at least 2 other symptoms of depression.
Many people with dysthymia develop major depressive episodes.
of depression also occur in people with bipolar disorder.
In this disorder, depression alternates with mania, which
is characterised by abnormally and persistently elevated
mood or irritability and symptoms including overly-inflated
self-esteem, decreased need for sleep, increased talkativeness,
racing thoughts, distractibility, physical agitation, and
excessive risk taking. Because bipolar disorder requires
different treatment than major depressive disorder or dysthymia,
obtaining an accurate diagnosis is extremely important.
Depression can be devastating to family relationships, friendships,
and the ability to work or go to school. Many people still
believe that the emotional symptoms caused by depression
are "not real," and that a person should be able
to shake off the symptoms. Because of these inaccurate beliefs,
people with depression either may not recognise that they
have a treatable disorder or may be discouraged from seeking
or staying on treatment due to feelings of shame and stigma.
Too often, untreated or inadequately treated depression
is associated with suicide.
situations where medication, psychotherapy, and the combination
of these interventions prove ineffective, or work too slowly
to relieve severe symptoms such as psychosis (e.g., hallucinations,
delusional thinking) or suicidality, electroconvulsive therapy
(ECT) may be considered. ECT is a highly effective treatment
for severe depressive episodes. The possibility of long-lasting
memory problems, although a concern in the past, has been
significantly reduced with modern ECT techniques. However,
the potential benefits and risks of ECT, and of available
alternative interventions, should be carefully reviewed
and discussed with individuals considering this treatment
and, where appropriate, with family or friends.
Brain imaging research is revealing that in depression,
neural circuits responsible for moods, thinking, sleep,
appetite, and behaviour fail to function properly, and that
the regulation of critical neurotransmitters is impaired.
research, including studies of twins, indicates that genes
play a role in depression. Vulnerability to depression appears
to result from the influence of multiple genes acting together
with environmental factors.
research has shown that stressful life events, particularly
in the form of loss such as the death of a close family
member, may trigger major depression in susceptible individuals.
hypothalamic-pituitary-adrenal (HPA) axis, the hormonal
system that regulates the body's response to stress, is
overactive in many people with depression. Research findings
suggest that persistent over activation of this system may
lay the groundwork for depression.
of brain chemistry, mechanisms of action of antidepressant
medications, and the cognitive distortions and disturbed
interpersonal relationships commonly associated with depression,
continue to inform the development of new and better treatments.