RELATIONSHIP BETWEEN AUDITORY P300 AMPLITUDE AND AGE-OF-ONSET OF SCHIZOPHRENIA IN OLDER PATIENTS

Auditory P300 amplitude reductions are well-established in young adult s with schizophrenia. Little is known, however, regarding the P300 in older schizophrenia patients, especially those with late onset. We stu died 28 middle-aged and elderly (mean age = 62.7 years) patients [14 w ith early onset schizophrenia (EOS) and 14 with late onset schizophren ia (LOS)] and 14 normal comparison (NC) participants using an auditory oddball paradigm. Event-related potentials were recorded from 15 scal p electrodes and six non-scalp sites. There were no significant differ ences between EOS and LOS groups in neuroleptic dosage, symptom severi ty, reaction times, target-detection accuracy, or N100 and N200 ERP me asures. The EOS, but not the LOS, group had significantly smaller audi tory oddball P300 amplitudes than the NC group. Twelve of the 14 LOS p atients had P300 amplitudes in the normal range. Smaller P300 amplitud es were associated with earlier age of onset (r = 0.48), longer durati on of illness (r = -0.49) and more severe alogia (r = - 0.50). We conc lude that P300 abnormalities in schizophrenia may be a marker for a di sease subtype with early onset and more severe information-processing deficits. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.