| Lifetime prevalence associated with depressive symptoms and major depressive disorder: | About 13%-20% for significant depressive symptoms represents
the lifetime prevalence rate. For major depressive disorder the lifetime prevalence rate is about 3.7%-6.7%. |
| Comparative likelihood of
major depressive disorder as a function of gender: | Major depressive disorder occurs about 2 to 3 times more frequently in adolescent and adult females compared to adolescent and adult males. With respect to prepubertal children, boys and girls are equally susceptible. Rates of these symptom occurrences and major depressive disorder
are highest in the 25-44 year-old age group. |
| Factors that appear involved in causing major depressive disorder: | Although the specific cause of major depressive disorder remains to be elucidated, several etiologic factors appear important; these include: psychodynamic, socioenvironmental, genetic, and biochemical factors. |
| Relationship between a significant personal loss and the subsequent development of depression: | Probably less than 20% of individuals experiencing death or loss of a loved one become clinically depressed. |
| Biological theories of depression-neurotransmitter involvement: | Clinically effective antidepressant agents influence postsynaptic signaling of serotonin, norepinephrine or both. This finding suggested a hypothesis that depression stems from a neurotransmitter deficiency,
with this imbalance being corrected by the drug. More recent findings focus on
integration of several intracellular signaling pathway elements regulating
neuronal responses. |
| Intracellular signals that may affect neuronal responses important for understanding antidepressant drug mechanism of actions: | Changes in G protein, alterations in cAMP (cyclic adenosine monophosphate), alterations in protein kinase enzyme activity, changes in gene transcription. |
| Physiology of depression: underlying mechanism(s) responsible- | Depression may result from abnormal intracellular signal transduction and/or gene expression. |
| Other than serotonin and norepinephrine, other neurotransmitters which may be important in affecting mood: | GABA, histamine, glycine, acetylcholine, melatonin |
|
Neuropeptides that may be important in affecting or regulating mood: |
Endorphins, enkephalins, corticotropin-releasing hormone, vasopressin, substance P, cholecystokinin. |
|
Hormones that may play an important role and move modulation: |
Thyroid, adrenal hormones |
| Biological theory of depression: neuroendocrine factors: | Emotional trauma may precede depression onset. Furthermore, emotional trauma may proceed onset of endocrine disorders including hyperthyroidism and Cushing's disease. Both of these syndromes are frequently associated with psychological changes often involving mood and cognition. The precise relationship between endocrine changes and psychological disturbance remains to be elucidated. |
| The two endocrine systems most substantively studied in psychiatry: | Hypothalamic-pituitary-thyroid (HPT) axis and the hypothalamic-pituitary-adrenal (HPA) axis. |
| Major depression and cortisol secretion: | About 50% of patients diagnosed with major depression also present with
a cortisol hypersecretion that normalizes after the depression results. |
| Biological theory of depression and early life stress: | Early childhood trauma which include physical or emotional abuse, parental loss or neglect
may result in long-lasting changes in neuroendocrine, neurochemical and psychophysiological systems. These effects
may represent a biological basis for increased risk of depression. |
| Family history and risk factors for major depressive disorder: | High-risk in families with a history of alcoholism (8%) or depression (7%). |
| Menopause as a risk factor for major depressive disorder: | No relationship |
| Social network as a risk factor for depression: | Likely risk factor associated with a relative lack of interpersonal relationships. |
| Personality aspects-risk factors for major depressive disorder: | Traits that may predispose to depression include insecurity, introvertedness., stress sensitivity, unassertive, obsessive, dependent |
| Race as a risk factor for major depressive disorder: | Major depressive disorder may be less common in African-Americans. |
| Social class as a risk factor for major depressive disorder: | No apparent relationship |