| Huntington's Disease patients' performances on objective measures of olfactory information processing have not been reported to date. The present study investigated olfactory functioning in HD using such a measure: the olfactory event related potential (OERP). Olfactory and auditory ERPs were recorded monopolarly from Fz, Cz, and Pz electrode sites in eight patients with HD and eight age- and gender-matched control participants. Results demonstrated that individuals with HD were delayed compared to controls on all components of the OERP, especially the P3 component. The effect size for OERP P3 latency (eta2 = .72) was larger than for the auditory P3 (eta 2 = .24), which has been previously shown to be delayed in HD. These findings extend our understanding of the olfactory deficits in HD, and suggest that the OERP may be an important tool for future research with this population.; The present study also used the OERP to attempt to identify olfactory deficits in individuals at risk for Huntington's disease but not yet demonstrating symptoms. Olfactory and auditory ERPs were recorded monopolarly from Fz, Cz, and Pz electrode sites in eight individuals at risk for HD and eight age- and gender-matched control participants. The stimuli were amyl acetate (1492 ppm) and a 500 Hz tone, presented in two separate sessions with a 45-second inter-stimulus interval. The latencies and amplitudes of ERP components N1, P2, N2, and P3, as well as interpeak amplitudes N1-P2, N1-P3, and N2-P3, were assessed. In addition, several neuropsychological and psychophysical measures were obtained on all individuals. Results demonstrated that at-risk individuals are significantly delayed on the P3 component of the OERP. In addition, these individuals identified significantly fewer odors than controls on the San Diego Odor Identification test. No differences between groups were found on the neuropsychological or other psychophysical measures. These findings suggest that the ability to cognitively process olfactory information is deficient prior to the diagnosis of HD in those at risk. |
