In their study, Maziade et al1 presented
challenging data concerning a possible early brainstem auditory evoked potential
response marker for an autistic phenotype. The authors demonstrated that the
I-III interpeak latency (IPL) of brainstem auditory-evoked potentials (BAEP)
was prolonged not only in persons with autism, but also in their unaffected
first-degree relatives compared with age-matched controls. By providing a
neurophysiological marker of the autistic phenotype, this finding could be
very important to our understanding of autism. However, the authors reported
that in 52% of families, neither the proband nor the relatives showed an abnormally
prolonged IPL. This finding suggests that BAEP-impaired and -nonimpaired subjects
might represent subgroups, and that they should be separated for analysis.
If prolonged ILP is not a continuous but a dichotomous variable, and thus
indicates subgroups rather than a continuous spectrum, then neither a correlation
with autistic symptoms for the whole sample nor the average IPL is likely
to be informative in revealing the exact nature of this phenomenon.
Nagy E, Loveland KA. Prolonged Brainstem Auditory Evoked Potentials: An Autism-Specific or Autism-Nonspecific Marker. Arch Gen Psychiatry. 2002;59(3):288-289. doi: