7. • The prevalence rate of mood disorders is 1.5
percent, and it is uniform throughout the world
8. Etiology
The etiology of mood disorders is currently
unknown. However, several theories have been
propounded which include:
9. BIOLOGICAL THEORIES
Genetic hypothessis
Geneticfactorsare very important
in predisposing an individual to mood
disorders. The lifetime risk for the first-degree
relatives of patients with bipolar mood disorder
is 25%and of normal controls is 7%.
10. The lifetime risk for the children of one parent
with mood disorder is 27%and of both parents
with mood disorder is 74%. The concordance
rate for monozygotic twins is65%and for
dizygotic twins is 15%.
11. Biochemical theories
A deficiency of norepinephrine
and serotonin has been found in depressed
patients and they are elevated in mania.
Dopamine, GABA and acetylcholine are also
presumably involved.
12. Psychosocial Theories
• Psychoanalytic theory
According to Freud (1957)
depression results due to loss of a "loved object",
and fixation in the oral sadistic phase of
development. In this model, mania is viewed as a
denial of depression.
13. • Behavioral theory
This theory of depression Connects depressive
phenomena to the experience of uncontrollable
events. According to this model, depression is
conditioned by repeated losses in the past.
14. Cognitive theory
According to this theory depression
is due to negative cognitions which includes:
• Negative expectations of the environment
• Negative expectations of the self
• Negative expectations of the future
These cognitive distortions arise out of a defect
in cognitive development and cause the individual
to feel inadequate, worthless and rejected by
others.
