A recent study examining the relationship between neuropsychological performance and three different indices of cannabis use in schizophrenia has revealed that use of cannabis is linked with enhanced cognitive functioning in schizophrenia.
The indices were DSM-IV lifetime abuse/dependence, frequency of use, and recency of use. Sixty males suffering from schizophrenia/schizoaffective disorder and 17 healthy males were recruited as part of the study. The two groups were matched for age, education years, and premorbid IQ and the researchers assessed medical history, substance use, and psychiatric symptoms of the recruits. A neuropsychological battery was also administered for assessing attention/processing speed, executive functions, memory, and perceptual organization. Substance use within twenty-four hours of cognitive assessment was screened by urine analysis, and a range of confounds were controlled.
It was revealed that 44 participants met DSM-IV criteria for lifetime cannabis abuse/dependence in the schizophrenia group and there were three mutually exclusive frequency-of-cannabis-use subgroups comprising “high” frequency users (n=11), “medium” frequency users (n=7), and “low” frequency users (n=34) over the preceding year. There were also four mutually exclusive recency-of-cannabis-use categories comprising “cannabis abuse/dependence in the past week” (n=11 users), “non-dependent cannabis use in the past week” (n=7 users), “non-dependent cannabis use in the past month, but prior to the past week” (n=7 users), and “non-dependent cannabis use prior to the past month” (n=9 users).
Moreover, the control group fared better than the schizophrenia group in all cognitive domains. A larger proportion of participants, within the schizophrenia group, with lifetime cannabis abuse/dependence demonstrated better performance than those without lifetime abuse/dependence on a component of psychomotor speed.
Recency and frequency of cannabis use were also linked with improved neuropsychological performance, predominantly in the domains of attention/processing speed and executive functions. In conclusion, the use of cannabis was found to be associated with improved cognitive functioning in schizophrenia.
National Center for Biotechnology Information