Levels of endocannabinoid metabolizing enzymes are not related with BDNF levels in patients with schizophrenia: a case-controlled study

PURPOSE: While the pathogenesis of schizophrenia has yet to be fully clarified, a huge amount of data suggests the involvement of endocannabinoid system and neurotrophic factors in schizophrenia. Nevertheless, only a very limited number of studies have investigated these two systems together. With this disease containing various unknowns, our primary aim was to simultaneously investigate the serum levels of fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes, which play significant roles in endocannabinoid system mechanisms, and brain-derived neurotrophic factor (BDNF) as a frequently investigated and important neurotrophic factor in patients with psychiatric disorders. METHODS: This study comprised a total of 34 (24 men, 10 women) schizophrenia patients and 35 (26 men, 9 women) healthy control groups, aged between 18 and 65 years. PANNS and Clinical Global Impression Scale Severity of Illness (CGI-SI) were used to measure disease severity. Serum FAAH, MAGL and BDNF levels of the patients and controls were measured by conventional methods. FINDINGS: Compared to the healthy control group, patients with schizophrenia had decreased FAAH activity, increased MAGL activity and lower BDNF levels. No correlation was noted between BDNF serum levels with FAAH or MAGL activities. CONCLUSION: The findings of the present study showed that there were changes in the levels of metabolizing enzymes of the endocannabinoid system in schizophrenia patients, and these changes were accompanied by a decrease in BDNF levels. While this study provided important information, primarily investigating endocannabinoids and the neurotrophic factor in schizophrenia, future research should be conducted on better designed patient groups and investigate additional parameters.