CHANGES OF NITRIC OXIDE SERUM LEVELS WITH SSRI USE IN GERIATRIC OBSESSIVE COMPULSIVE DISORDER

Abstract

Nitic oxide (NO) is an inflammatory mediator, shown to have a possible role in pathophysiology of some psychiatric disorders such as obsessive compulsive disorder (OCD). Some studies on animal models have shown that increased NO production could lead to reversed effect of selective serotonin reuptake inhibitors (SSRIs). This study tries to assess the correlation of NO serum levels with the use of SSRIs in geriatric OCD. Patients aged 60 and older, diagnosed with OCD and candidates of receiving an SSRI drug; entered this study voluntarily. For assessing NO serum levels, blood samples were drawn from subjects before starting drug therapy and when the patient had shown signs of response to the drug. NO concentrations were measured by Nitrate/nitrite colorimetric assay kit (Griess method). 27 patients met our inclusion criteria. Mean serum concentration of NO prior to drug therapy was 29.94 ± 18.9 µmol/L. This value was 17.55 ± 2.75 µmol/L when the symptoms showed signs of improvement. With a p-value of 0.041, there was a significant correlation between NO levels and the use of SSRIs. Mean duration of therapy for these cases was 4.03 ± 0.5 months. Type of the SSRI, duration of disease, gender and severity of OCD did not have any relationship with NO levels. Our results show that geriatric patients on SSRI drugs had lower NO serum concentrations when their OCD symptoms started to resolve. Such data can be helpful in finding a predictive factor of response to therapy, and augmentation therapy with future drugs that target NO synthesis.