Impaired P50 sensory gating in Machado-Joseph disease.
OBJECTIVE
Machado-Joseph disease (MJD), an autosomal dominant spinocerebellar degeneration caused by an expanded CAG repeat on chromosome 14q32.1, is a disorder with wide range of neurological findings and brain regions involved. Studies evaluating neurophysiological parameters related to sensory gating in MJD are lacking.


METHODS
This study intends to investigate P50 suppression, an auditory mid-latency evoked potential in a test-conditioning paradigm, considered as an index of sensory gating function. Twelve patients with MJD, 24 normal subjects and 12 schizophrenic patients were evaluated.


RESULTS
MJD subjects had higher P50 ratios as compared to normal subjects (76.2 vs. 42.1%, P = 0.001), but similar to the group of schizophrenic patients. The difference from controls was due to greater test amplitudes (3.4 vs. 2.0 microV, P = 0.002), rather than to conditioning amplitudes. Latencies were higher for the MJD subjects than for controls (60.4 vs. 56.1 ms, P = 0.016).


CONCLUSIONS
MJD may present sensory gating dysfunction. However, the pattern of this dysfunction seems to slightly differ from that classically found in schizophrenia, were both test and conditioning amplitudes seem to be implicated.


CONCLUSIONS
These results point out the P50 paradigm as a potential tool for further neurophysiological surveying in MJD.
Ghisolfi
Eduardo S
ES
Departamento de Bioquímica da Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. ghisolfi@pucrs.br
Maegawa
Gustavo H B
GH
Becker
Jefferson
J
Zanardo
Ana Paula
AP
Strimitzer
Ivo M
IM
Prokopiuk
Alexandre S
AS
Pereira
Maria Luiza
ML
Carvalho
Thiago
T
Jardim
Laura B
LB
Lara
Diogo R
DR
D000328:Adult; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D017827:Machado-Joseph Disease / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000503:physiopathology