Mood disorders and Major Depressive Disorder, in particular, appear to be some of the most
common psychiatric disorders with a high rate of comorbidity most frequently of anxiety or substance
abuse disorders (alcohol use disorder). In both cases – MDD and AUD, a number of immunological disturbances
are observed, such as chronic mild inflammation response, increased level of cytokines, hypercortisolaemia,
which lead to specific changes in brain neurotransmitter functions.
Some of the contemporary brain imaging techniques are functional magnetic resonance imaging (fMRI)
and magnetic spectroscopy which are most commonly used to assess the brain metabolism and functional
connectivity changes such as altered responses to emotional stimuli in MDD or overactivation of
ventromedial prefrontal areas during delayed and underactivation of dorsolateral prefrontal regions during
impulsive reward decisions in AUD and dysfunction of gamma-aminobutyric acid (GABA) and/or
glutamate neurotransmitter systems, low NAA and myo-Inositol in both MDD and AUD.