The P50 auditory event-evoked potential in adult attention-deficit disorder: comparison with schizophrenia.
BACKGROUND
Attention-deficit/hyperactivity disorder (ADHD) and schizophrenia are both conceptualized as disorders of attention. Failure to inhibit the P50 auditory event-evoked response, extensively studied in schizophrenia, could also occur in ADHD patients, if these two illnesses have common underlying neurobiological substrates.


METHODS
This study examined the inhibition of the P50 auditory event-evoked potential in 16 unmedicated adults with ADHD, 16 schizophrenic outpatients, and 16 normal control subjects. Auditory stimuli were presented in a paired stimulus, conditioning-testing paradigm.


RESULTS
The amplitude of initial or conditioning P50 response did not differ between the three groups; however, significant effects of psychiatric diagnosis on the amplitude of the test response and the ratio of the test to the conditioning response amplitudes were observed. Schizophrenic patients' P50 ratios and test amplitudes were higher than both the ADHD and normal groups.


CONCLUSIONS
Adults with ADHD do not have the inhibitory deficit seen in patients with schizophrenia, suggesting that the mechanism of attentional disturbance in the two illnesses may be fundamentally different.
Olincy
A
A
Department of Psychiatry, University of Colorado Health Sciences Center, Denver 80262, USA.
Ross
R G
RG
Harris
J G
JG
Young
D A
DA
McAndrews
M A
MA
Cawthra
E
E
McRae
K A
KA
Sullivan
B
B
Adler
L E
LE
Freedman
R
R
D000328:Adult; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D016022:Case-Control Studies; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009433:Neural Inhibition; D009538:Nicotine / Q000494:pharmacology; D012559:Schizophrenia / Q000503:physiopathology*
D009538:Nicotine