Sex differences in visual evoked potentials in school-age children: what is the evidence beyond the checkerboard?

Visual evoked potentials (VEPs) are known to be influenced by several biological variables, including sex. In adult populations studies using conventional high-contrast checkerboard have shown that females display larger amplitudes and shorter latencies than males. To date, few studies have been conducted in children; the available data suggests that girls display significantly larger amplitudes than boys but the effect on latency is absent or negligible. We investigated sex-related VEP differences in 149 school-age (11.3 ± 0.6 years) children from Northern Quebec using several VEP protocols: achromatic pattern-reversal VEPs at high (95%) and low contrast (30%, 12% and 4%), as well as motion-onset VEPs and isoluminant pattern-reversal VEPs. Girls showed significantly larger amplitudes in achromatic VEPs for most of the contrast levels as well as in N2 response to motion-onset. No significant difference was found regarding the amplitude of isoluminant VEPs. In addition, girls showed shorter latencies for the achromatic N75 and a trend (p<0.1) for the P100, regardless of the contrast level. Interestingly, this latency effect appeared mostly due to head size, not sex. No differences in latency were found for motion or isoluminant responses. Overall, these findings show that sex-related differences are present in children mostly in VEP amplitude not only for high contrast achromatic pattern-reversal but also for low contrast levels and motion-onset VEPs, suggesting that sex affects VEP responses in a general fashion.