Cannabis use and sensorimotor gating in patients with schizophrenia and healthy controls

Schizophrenia patients and healthy cannabis users show different attention-dependant alterations in prepulse inhibition (PPI). It is of interest then to examine PPI in patients with schizophrenia who use cannabis, given the hypothesized association between cannabis use and schizophrenia.

Prepulse inhibition was measured in 34 healthy cannabis users, 32 healthy non-using controls, 20 patients with schizophrenia who were current cannabis users, and 44 non-using patients with schizophrenia. PPI was measured across a range of startling stimulus intensities, during two attention set conditions. Curves of best fit were fitted to the startle magnitudes, across the stimulus intensities. A number of reflex parameters were extracted from these logistic functions.

Similar to healthy cannabis users, cannabis-using patients showed altered PPI of Threshold, only when instructed to sustain attention to the auditory stimuli. Conversely, non-using patients with schizophrenia showed reduced PP of R(MAX) only when instructed to ignore the auditory stimuli.

Cannabis use in patients with schizophrenia is associated with a similar pattern of attention-dependant alterations in PPI to that observed in healthy cannabis users. This is different to those observed in patients with schizophrenia who do not use cannabis and may be as a result of a dysfunction of sustained attention.