[Experimental study on sensory gating in generalized anxiety and obsessive compulsive disorders]

To observe the characteristics of sensory gating P50 in generalized anxiety disorder (GAD) and in obsessive compulsive disorder (OCD) patients.

Auditory evoked potentials P50 were recorded in 41 GAD patients, 69 OCD patients and in 58 normal controls by the conditioning/testing paradigm presented with auditory double clicks stimuli, using American Nicolet Bravo instrument.

(1) No significant differences was found in latencies of S1-P50 and S2-P50 among these three groups (P > 0.05). (2) Significant differences were found in indices of S1-P50 amplitudes (NC: 6 +/- 3, GAD: 3 +/- 2, OCD: 5 +/- 3, P < 0.01), S2-P50 amplitudes (NC: 2 +/- 1, GAD: 4 +/- 1, OCD: 2 +/- 1, P < 0.01), S2/S1, S1-S2 and 100(1-S2/S1). (3) Compared with NC, GAD and OCD patients showed a decreased S1-P50 amplitude and OCD patients also showed an increased S2-P50 amplitude. (4) P50 inhibition significantly decreased in GAD and OCD patients. The values of S2/S1 ratio were 39% +/- 22% in NC, 50% +/- 29% in GAD and 88% +/- 42% in OCD (P < 0.01). (5) Both S1-S2 and 100 (1-S2/S1) decreased in GAD and OCD patients (NC: 3 +/- 2, 61 +/- 22; OCD: 1 +/- 1, 15 +/- 22; GAD: 3 +/- 3, 50 +/- 29. P < 0.01). (6) Compared with GAD, OCD patients showed a lower S2/S1 ratio (P < 0.01) and a higher value of S1-S2 (P < 0.01) and 100 (1-S2/S1) (P < 0.01).

The anxiety disorder patients has sensory gating deficits. The inhibition deficit can be measured by auditory evoked potential P50. And S2/S1 ratio, S1-S2 and 100(1-S2/S1) may be biological markers of GAD and OCD patients.