Somatosensory amplification and its relationship to somatosensory, auditory, and visual evoked and event-related potentials (P300)

Somatosensory amplification refers to the tendency to experience benign and ambiguous somatic sensation as intense, noxious, and disturbing. The construct is helpful in assessing the perceptual style of a variety of somatizing conditions, but there is no human study clarifying the effects of neurological function on somatosensory amplification. The present study examines the relationship between somatosensory amplification and different types of evoked potentials. In 33 healthy volunteers (mean age 24 years, 18 men), latencies and amplitudes were recorded using the following parameters: short-latency somatosensory, brainstem-auditory, and visual evoked potentials (SSEP, BAEP, and VEP, respectively) and auditory event-related potentials (ERP). All subjects completed questionnaires for the Somatosensory Amplification Scale (SSAS), 20-item Toronto Alexithymia Scale (TAS-20), and Profile of Mood State (POMS). The SSAS scores were significantly associated with the P200 latency (p=0.020) and P300 amplitude of ERP (p=0.041), controlling for the significant effect of the TAS and POMS depression and tension-anxiety scales. The SSEP, BAEP, and VEP latencies or amplitudes were not statistically significant (all p>0.05). When the subjects were divided into high and low SSAS groups based on the median of the SSAS scores, the P300 amplitude of ERP significantly discriminated the two groups (p=0.023) by multiple logistic regression analysis. Although the findings should be viewed as preliminary because of the small sample size, somatosensory amplification appears to reflect some aspects of long-latency cognitive processing rather than short-latency interceptive sensitivity from the viewpoint of encephalography.