This is a 380 heavy drinker patient's sample recruited from twelve primary care centers. The patients were screened using The Alcohol Use Disorders Identification Test (AUDIT > 8). Neuropsicological tests done at the base line and after the 4 years of the study were the Continous Performance Test (CPT) and the Barrat Impulsivity scale. The alcohol and cocaine consume accumulated along the four years was also study.

The two variables of the CPT (ommission and commission errors) had a significant correlation with the alcohol and cocaine use accumulated in these four years. The variable that was associated with a greater risk of making more commission and ommission errors was the cocaine risk consumption. The years of study were protective variable.

The most important conclusion of this study is that alcohol and cocaine use produces a modification in the conductual paradigm of impulsivity characterized by the inhibition difficulties measured by the CPT. Also, the cocaine use effects are added respect to the alcohol ones and finally that cocaine plus alcohol effects over the number of ommission and commission errors are more potent that the ones made only with alcohol.