Depression biological hypotheses

To understand the biological basis of depression, including the monoamine hypothesis, the neurotransmitter receptor hypothesis and the hypothesis of reduced activation of brain neurotrophic factors. 

As with the antidepressants discus.sed earlier, the major biological theory regarding mania concerns the monoamine ncurotransmitters. In depression, undcractivin of neurotransmitters is hypothesized, and the hypothesis for mania is increased flinctional... 

MAO inhibitors were at the center of interest. Both as experimental tools and as therapeutic agents MAO inhibitors had an important influence on the development of the widely accepted hypothesis that 1. depression is associated with diminished monoaminergic tone in the brain, and 2. depressed patients treated with antidepressants become elated because of enhanced biological activity of monoamine transmitters in the central nervous system. 

Traditional explanations of the biologic basis of depressive disorders have focused largely on NE and 5-HT however, most of the evidence that coalesced into the biogenic amine hypothesis of depression does not clearly distinguish between NE and DA. ... 

An association between cannabis use and neuropsychiatrie conditions is of major importance because of the potential for the use of caimabis as a recreational drug or medicine and also for understanding the biological mechanisms by which catmabinoids act on brain structure and function. In this chapter we review evidence for a number of hypotheses which have been proposed to describe the putative role of caimabis use in the precipitation of psychosis. The majority of studies support the vulnerability hypothesis, especially with respect to schizophrenia. The hypothesis that the consumption of cannabis is a form of self-medication for the symptoms of schizophrenia and depression has also gained support. 

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