Dopamine Hypothesis of Schizophrenia

The dopamine hypothesis is an explanation for schizophrenia, which believes that the disease is caused by increased levels of the neurotransmitter. However, it has been revised and added to multiple times, as scientific advancements have been made. The first version stated that increased dopamine activity was the cause of schizophrenia and noted that the D2 receptor was the most significant in responding to it, however it failed to identify any specific brain areas that this would occur in and neglected the fact that differences in dopamine abnormalities could cause either positive or negative symptoms.

The simplistic nature of version one of the dopamine hypothesis led to Davis’ version two in 1991, which had newer and more credible evidence. This evidence identified that schizophrenia habitually presents itself after an increase in sub-cortical dopamine, especially in the striatum and specifically with the D2 receptor. This suggested that abnormalities in in the prefrontal cortex may have been causing the abnormalities in the limbic system and identified how abnormalities can cause different symptoms. Nonetheless, this version was still deemed to be over simplified and biologically reductionist.

Further advancements led to a third version of the dopamine hypothesis, which is our most accurate and scientifically credible explanation to date. It identified that most schizophrenics have abnormally high presynaptic dopamine production in their striatum due to also tending to have 10-20% higher levels…