Amplitudes and latencies of N2 and P2 peaks of Aδ- (Aδ-LEP) and C-fibre- (C-LEP) related LEPs were evaluated.
Depressed patients showed significantly decreased Aδ-LEP amplitudes (N2 peak: P=0.019; P2 peak: P=0.024) and delayed C-LEP latencies (P2 peak: P=0.0495; N2 peak: P=0.0556). In contrast, C-LEP amplitudes and Aδ-LEP latencies were unaffected.
Our results might be suggestive of the differential impact of physiological changes on pain processing in depression. Thus, Aδ-LEP might reflect the physiological correlate of the augmented superficial pain thresholds during depression.
On the contrary, the C-fibre component mediates the facets of pain processing, outlasting the stimulation period, and has been shown to be exaggerated in chronic pain states. Therefore, the functional over-representation of the C-fibre component found in our study might be a possible link between depression and associated pain complaints.