The role of glutamatergic dysfunction in the pathophysiology of OCD has hardly been explored despite recent reports implicating glutamatergic dysfunction in OCD. We decided to investigate CSF glutamate levels in adult OCD probands compared to psychiatrically normal controls. In total, 21 consenting psychotropic drug-naïve adult OCD patients, diagnosed using SCID-IV-CV, and 18 consenting psychiatrically normal controls with age within 10 years of age of the patients, who did not have any history of head injury or neurological illness, were included into the study. Aseptically collected and stored CSF samples obtained from the patients and control subjects were used for glutamate estimation, which was carried out by a modification of the procedure described by Lund (1986). CSF glutamate (mmol/l) level was found to be significantly higher [F(1,31) ¼ 6.846, p ¼ 0.014] in OCD patients (47.1274.25) compared to control subjects (41.3673.63) on analysis of covariance. There was no effect of gender, age, duration of illness, Y-BOCS score, or CGI-S score on CSF glutamate levels. Our study provides preliminary evidence implicating glutamatergic excess in the pathophysiology of OCD, which needs to be further explored by studies from other centers involving larger sample sets from different age groups.

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Although serum autoantibodies directed against basal ganglia (BG) implicate autoimmunity in the pathogenesis of obsessive-compulsive disorder (OCD), it is unclear whether these antibodies can cross the blood-brain barrier to bind against BG or other components of the OCD circuit. It is also unclear how they might lead to hyperactivity in the OCD circuit. We examined this by investigating the presence of autoantibodies directed against the BG or thalamus in the serum as well as CSF of 23 OCD patients compared with 23 matched psychiatrically normal controls using western blot. We further investigated CSF amino acid (glutamate, GABA, taurine, and glycine) levels and also examined the extent to which these levels were related to the presence of autoantibodies. There was evidence of significantly more binding of CSF autoantibodies to homogenate of BG as well as to homogenate of thalamus among OCD patients compared with controls. There was no significant difference in binding between patient and control sera except for a trend toward more bands to BG and thalamic protein corresponding to 43 kD among OCD patients compared with controls. CSF glutamate and glycine levels were also significantly higher in OCD patients compared with controls, and further multivariate analysis of variance showed that CSF glycine levels were higher in those OCD patients who had autoantibodies compared with those without. The results of our study implicate autoimmune mechanisms in the pathogenesis of OCD and also provide preliminary evidence that autoantibodies against BG and thalamus may cause OCD by modulating excitatory neurotransmission.

Although obsessive-compulsive disorder (OCD) is classified as an anxiety disorder in the DSM-IV, recent considerations for a reclassification into an obsessive-compulsive spectrum disorders (OCSDs) cluster are gaining prominence. Similarities in symptomatology, course of illness, patient population, and neurocircuitry of OCD and OCSD are supported by comorbidity, family, and neurological studies, which also offer a critical re-evaluation of the relationship between OCD and anxiety disorders. This review examines potential classifications of OCD among the wider spectrum of affective disorders and at the interface between affective disorders and addiction. In addition, it has been suggested that the categorical diagnostic approach would be enhanced by an additional dimensional approach, including parameters such as stability of mood and ability to sustain attention. With further studies, it is ultimately the goal to define OCD and related disorders based on endophenotypes.Despite efforts in this field, there are several fundamental unresolved issues, including the question of which disorders should be grouped together in this category and which characteristics to include as their shared common features. A reclassification of OCD among the OCSDs would allow for better scrutiny of distinct obsessive-compulsive symptoms, as currently this disorder often goes undetected in patients who complain of a broad symptom of anxiety. Advantages and disadvantages of establishing OCSDs and its implications for diagnosis, treatment, and research are discussed.

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