Anticholinergic-neuroleptic antagonism in terms of positive and negative symptoms of schizophrenia: implications for psychobiological subtyping.

In three studies of comparable design, 47 schizophrenics received anticholinergic anti-Parkinsonism (AP) medications for two to four weeks along the course of neuroleptic treatment. Clinical ratings during the AP phase were contrasted against the preceding and following two-week periods on neuroleptic alone, and these changes were analysed for a total of 27 psychopathology dimensions and for clusters of seven positive and seven negative symptoms. Schizophrenics overall exhibited significant exacerbation of total psychopathology, and positive but not negative symptoms. Only those with a predominantly positive syndrome when drug-free were susceptible to AP therapeutic reversal. However, other subgroup analyses revealed worsening of total psychopathology and positive symptoms among catatonic, schizophreniform, chronic, and good outcome cases, but negative symptoms alone were significantly increased among paranoids. The results were not supportive of a positive-negative dichotomy of schizophrenia, but instead suggested a tripartite model: a distinct paranoid group and a division of the non-paranoids into a positive and a negative type.