The effect of behavior therapy on caudate N-acetyl-l-aspartic acid in adults with obsessive-compulsive disorder.

Previous studies suggest that baseline differences in neuronal markers between patients with obsessive-compulsive disorder (OCD) and healthy controls no longer exist following successful pharmacotherapy. The current study used proton magnetic resonance spectroscopy (MRS) to investigate differences in absolute concentrations of neurochemicals (i.e., N-acetyl-l-aspartic; NAA) in the head of the caudate nucleus (HOC) and orbital frontal white matter (OFWM) between 15 adults with OCD and a sex- and age-matched control group, as well as the effects of behavior therapy on these chemicals. Behavior therapy was associated with a significant increase in left HOC NAA. When the analyses were restricted to only pairings with complete data (OCD patient, control, post-treatment), the levels of left HOC NAA were significantly lower in patients compared to controls, and increased significantly with treatment. Exploratory analyses suggested that levels of NAA and Cr (creatine) in the right OFWM may be significantly lower in the OCD group than the control group. The results raise the possibility that successful behavioral treatment may be associated with increases in markers of neuronal viability, although other associations found in the literature were not replicated.