Brainstem auditory evoked potentials in experimental autoimmune dementia

Cognitive dysfunction may be induced in rats by immunization with cholinergic neuronal antigens and is associated with degeneration of nuclei in the septum and hippocampus and white matter tracts in the forebrain. Such rats are a putative model of Alzheimer's disease named experimental autoimmune dementia (EAD). The aim of the present study was to investigate brainstem auditory evoked potentials (BAEP) in EAD rats in order to define the extent of white matter tract involvement in this model. Clear reproducible evoked potentials were obtained and the normal range of BAEP in rats was established in adjuvant immunized controls. Measurements of inter peak latencies (IPL) I-IV in 9 EAD rats revealed that they were not significantly prolonged (3.00 +/- 0.22 ms, mean +/- S.E.M.) compared to 9 controls (2.80 +/- 0.08 ms), (P > 0.2, Student's t-test). The lack of significant change in IPL I-IV is compatible with preliminary histological findings and indicates that brainstem structures are generally unaffected in EAD.