Addictive disorders are frequent in schizophrenia and dual diagnose is the norm rather than the exception. Dopamine transmission is implicated both in addictive disorders as in psychotic diseases. The objective is to know if addiction is one independent dimension in schizophrenia or if it can be included in to the positive, negative or affective syndromes.

We conduct one cross-sectional study on 60 schizophrenia out-patients (43 male; average age: 38.9 years, SD 9.4). The diagnosis were: paranoid schizophrenia 26.7%, schizoaffective disorder 25.0%, residual schizophrenia 21.7%, other schizophrenia subtypes 26.6%. It was applied the PANSS and one addiction composite score (ACS) that reflects the life use of drugs and addiction: tobacco, coffee, alcohol, cannabis, cocaine, amphetamines, hallucinogens, opiates and gambling. For every substance and gambling were scored: first use, frequency, length of use, last time use and harmful consequences. All the scores were transformed in to Z values. Factor analysis using principal components (Varimax rotation) was performed introducing in the model: PANSS positive and negative items, depression item an the ACS.

Five factors were defined, that explains for 78.4 of the variance: negative (N1, N2, N3, N4, N6), disorganized (P2, P4, N5, N7), positive and depressive (P1, P3, G6), hostility (P5, P6, P7) and addictive (ACS).

Addiction is one independent dimension in schizophrenia, differentiated from positive, negative, disorganized and hostility syndromes. We propose the systematic study of addiction as one intrinsic dimension of schizophrenia due to its independence of other dimensions, its high prevalence and its clinical relevance.