According to a study published online in the journal Psychiatry Research, individuals with bipolar disorder who used cannabis showed higher neurocognitive performance than patients who did not use cannabis.
Researchers at The Zucker Hillside Hospital in Long Island, NY, in collaboration with a team at the Mount Sinai School of Medicine and the Albert Einstein College of Medicine in New York City, examined the difference in cognitive performance among 50 individuals with bipolar disorder who had a history of cannabis use, with 150 bipolar patients who had no history of cannabis use.
Both groups of patients were similar in age at bipolar onset. In addition, the groups did not differ in racial background, age, or highest education level achieved.
The team discovered that patients who used cannabis showed superior neurocognitive performance than those who did not. However, patients who used cannabis did not differ considerably on estimates of premorbid IQ.
The researchers explained:
"Results from our analysis suggest that subjects with bipolar disorder and history of (cannabis use) demonstrate significantly better neurocognitive performance, particularly on measures of attention, processing speed, and working memory.
These findings are consistent with a previous study that demonstrated that bipolar subjects with history of cannabis use had superior verbal fluency performance as compared to bipolar patients without a history of cannabis use. Similar results have also been found in schizophrenia in several studies."
They concluded, "These data could be interpreted to suggest that cannabis use may have a beneficial effect on cognitive functioning in patients with severe psychiatric disorders. However, it is also possible that these findings may be due to the requirement for a certain level of cognitive function and related social skills in the acquisition of illicit drugs."