The
third version of the Dopamine Hypothesis of Schizophrenia refers to the theory
that schizophrenic symptoms arise due to potential risk factors increasing
presynaptic dopaminergic signalling. Literature agrees that the dopamine
hypothesis has contributed to a significant understanding of the underlying
mechanisms of schizophrenia due dopaminergic dysregulation in specific pre
frontal brain regions (Brisch et al., 2014). Howes and Kapur (2009) acknowledge
that the Dopamine Hypothesis III gravitates towards “psychosis – in –
schizophrenia” (p.556), potentially limiting the extent to which is can be
applied to every aspect of schizophrenia. It should be acknowledged that schizophrenia
is not entirely psychotic and that negative and cognitive deficits need be
taken into account in regards to hyper dopaminergic states.