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Proponents of the monoamine hypothesis argue that this lag is that the neurotransmitter activity enhancement is the result of auto receptor desensitization, which can take weeks. [59] Intensive investigation has failed to find convincing evidence of a primary dysfunction of a specific monoamine system in people with MDD.
The neurotrophic hypothesis of depression [1] proposes that major depressive disorder (MDD) is caused, at least partly, by impaired neurotrophic support.Neurotrophic factors (also known as neurotrophins) are a family of closely related proteins which regulate the survival, development, and function of neurons in both the central and peripheral nervous systems.
However, the hypothesis is incomplete, as several lines of evidence suggests that depression is more than just a monoamine imbalance. For example, antidepressants usually take several weeks to reduce a patient's depressive symptoms, which is inconsistent with the finding that monoamine levels are affected within hours of using antidepressants. [5]
This article needs to be updated. The reason given is: Many outdated sources and information (older than five years). Please help update this article to reflect recent events or newly available information. (July 2024) Medical condition Major depressive disorder Other names Clinical depression, major depression, unipolar depression, unipolar disorder, recurrent depression Specialty Psychiatry ...
The pharmacology of antidepressants is not entirely clear.. The earliest and probably most widely accepted scientific theory of antidepressant action is the monoamine hypothesis (which can be traced back to the 1950s), which states that depression is due to an imbalance (most often a deficiency) of the monoamine neurotransmitters (namely serotonin, norepinephrine and dopamine). [1]
The onset of major depressive episodes or MDD often occurs in people in their mid-20s and less often in those over 65. The prevalence of depressive symptoms in the elderly is around 1–2%. [ 35 ] Elderly persons in nursing homes may have increased rates, up to 15–25%. [ 35 ]
Monoamine precursors are precursors of monoamines and monoamine neurotransmitters in the body. [ 1 ] [ 2 ] The amino acids L -tryptophan and L -5-hydroxytryptophan (5-HTP; oxitriptan) are precursors of serotonin and melatonin , while the amino acids L -phenylalanine , L -tyrosine , and L -DOPA (levodopa) are precursors of dopamine , epinephrine ...
After release into the synaptic cleft, monoamine neurotransmitter action is ended by reuptake into the presynaptic terminal. There, they can be repackaged into synaptic vesicles or degraded by the enzyme monoamine oxidase (MAO), which is a target of monoamine oxidase inhibitors, a class of antidepressants. [citation needed]