Gender differences in pattern reversal evoked potentials in normal elderly.

Pattern reversal evoked potentials (PREPS) were recorded in 51 normal elderly subjects (27 males, 24 females). Elderly females had shorter PlOO and NlSO latencies, greater P100-N150 amplitudes, and higher noise power than elderly males. The N1SO latency differences were significant even when PlOO latency effects were partialled out statistically. Gender differences in P100-Nl50 amplitude were independent of both noise power and PREP latency measures. These results provide evidence that, in the elderly, 1) gender differences in PREP amplitude reflect factors specific to CNS processing of visual stimuli rather than global CNS anatomic or physiological factors, 2) gender differences in PlOO latency reported in younger groups are also present in the elderly, and 3) there are separable factors underlying gender differences in NlSO and PlOO latencies in the elderly. DESCRIPTORS: Pattern reversal evoked potentials, PlOO, N150, Elderly, Gender differences. Gender is an important inter-subject variable which affects the amplitude and latency of pattern reversal evoked potential (PREP) components. The majority of studies throughout the age span have found both larger PlOO amplitudes and shorter Pl00 latencies in females (Allison, Wood, & Go& 1983; Erwin, 1980; Halliday, 1982; Halliday, Barrett, Carroll, & Kriss, 1982; Snyder, Dustman, & Shearer, 1981; Stockard, Hughes, & Sharbrough, 1979; for review see Shearer, Cohn, Dustman, & LaMarche, 1984). However, there have been some failures to find gender differences for both the amplitude and latency of PlOO (e.& Cohn, Kircher, Emmerson, & Dustman, 1985; Shearer & Dustman, 1980; Verma & Kooi, 1984), and an explanation for the inconsistency of findings has not yet been forthcoming. It has been hypothesized that rather than reflecting functional C N S differences between males and females, gender differences in amplitude result from differences in factors such as skull thickness, and gender differences in latency are a consequence of This research was supported by NIA Grant No. 1R01-AGO3334 and Veterans Administration General Medical Research Funds. We thank Jonathan Raz and Drs. Bruce Turetsky and Bernie Dolan for their assistance with this study. Address requests for reprints to: Dr. G. Fein, VA Medical Center (1 I6R), 41 50 Clement Street, San Francisco, differences in head size, body temperature, pupil size, attention and arousal, or monoamine or hormone levels. There have been consistent reports of longer P 100 latency in the elderly (Allison, Hume, Wood, & GoK 1984; Allison et al., 1983; Celesia & Daly, 1977; Shaw & Cant, 1980; Sokol, Moskowitz, & Towle, 1981). In a recent study, Verma and Kooi (1984) suggested that the increase in PlOO latency in the elderly is due to an increase in latency in females, with no increase in latency in males. In their crosssectional study with relatively small samples in each group, they found a significant difference between males and females in PI00 latency in the young, but no significant gender difference in the elderly. Because of the small sample sizes, their study had limited power to detect gender differences in the elderly and thus, their findings should be taken as tentative until replicated. In this paper, we present PREP data from 51 normal elderly men and women. We examined the latency and amplitude of P100, N150, and P200. We also estimated noise power as a measure of background EEG amplitude.