Positive and Negative Schizophrenia Symptoms and the Role of Dopamine

Presumably one function of an hypothesis is to provoke further thought and observation. Therefore, I welcome the critical comments of Ashcroft and colleagues ( Journal , March 1981, 138, 268–9) on my suggestion concerning the relationship between dopaminergic disturbances and the positive and negative symptoms of schizophrenia (Crow, 1980a, b). However, I think they have misunderstood the proposal and have underestimated some of the relevant evidence. I believe the evidence for two processes is more compelling than they have conceded and I note that in their own hypothesis they have introduced two factors to account for phenomena that both Mackay (1980) and I regard as a problem for the simple dopamine theory.