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Year : 2014  |  Volume : 35  |  Issue : 3  |  Page : 127-132

Study of olfactory identification and EEG in a sample of schizophrenic patients and their first-degree relatives as an endophenotype for schizophrenia

Neurology and Psychiatry Department, Faculty of Medicine, University of Alexandria, Egypt

Correspondence Address:
Nada A Mohamed
Consultant of Neurology and Psychiatry, Lecturer at University of Alexandria
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1110-1105.144327

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Objective Investigations of the genetic basis for mental disorders have recently focused on Endophenotypes as alternative phenotypes reflecting internal phenomena of organisms that define elements of mental disorders proximal to effects of genes. Olfactory deficits and abnormal resting state electroencephalogram (EEG) are among endophenotypes that have been reported in patients with schizophrenia. This study assessed olfactory function and resting state EEG abnormalities in patients (first episode and chronic schizophrenic patients) and again in the healthy first degree family members of schizophrenic patients to determine genetic liability for the disorder. Method The University Of Pennsylvania Smell Identification Test (UPSIT) was administered birhinally to three groups of subjects aged less than 65 years: 30 schizophrenic patients, 30 healthy first degree family members and 30 age- and sex-matched healthy volunteers. Resting EEG data were also collected from the study groups. Result A high percentage of schizophrenic patients (both first episodes and chronic patients) were microsmic compared with control subject (P = 0,000*). However there was no significant statistical difference between first episode patients and family group (P = 0.915). The family group showed significantly statistical difference in UPSIT score compared to control subjects (P = 0,001*).These group differences could not be accounted for by age, sex, medication exposure, education or smoking habit. Schizophrenic patients had no significantly statistical difference (on the augmented low frequency-delta component than did normal control subjects P = 0.167), and there was no significant difference in scores on the delta component between first episode and chronic schizophrenic patients (P = 713). In the family group no significant difference on the augmented low frequency-delta component than did normal control subjects (P = 176). Conclusions Impairment in olfactory identification ability was present from the onset of psychotic illness which suggests central causes. Olfactory identification deficit aggregates in healthy first-degree family members which may serve as a strong endophenotypic vulnerability marker. The findings of Resting state EEG collected from the study groups suggest that there is EEG abnormalities in schizophrenia patients and their first degree healthy family members, but because small sample size the data wasn't' conclusive and needs to be repeated on larger sample size.

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