The Evaluation of Olfactory Function in Patients With Schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Sensory Science

Background:

• Olfactory dysfunction is increasingly recognized as a potential biomarker in schizophrenia.
• Previous research indicates varied olfactory deficits in schizophrenia, but specific appraisal of odor pleasantness requires further investigation.

Purpose of the Study:

• To compare olfactory function (threshold, identification, intensity, pleasantness) between schizophrenia patients and healthy controls.
• To explore correlations between olfactory measures and schizophrenia illness characteristics, including duration, symptom severity (PANSS), and sex.

Main Methods:

• Utilized olfactory n-butanol threshold test, Iran smell identification test (Ir-SIT), and amyl acetate odor intensity/pleasantness rating test.
• Assessed 31 schizophrenia patients and 31 controls, performing all tasks unirhinally.
• Correlated olfactory performance with illness duration and Positive and Negative Syndrome Scale (PANSS) scores.

Main Results:

• Schizophrenia patients demonstrated significant olfactory impairments across all tested measures compared to controls.
• Longer schizophrenia duration correlated with poorer olfactory threshold and identification (Ir-SIT).
• Male schizophrenia patients showed disrupted odor pleasantness ratings compared to females and controls, which was associated with positive symptom severity.

Conclusions:

• Schizophrenia is associated with widespread olfactory deficits, including threshold and identification.
• Odor pleasantness appraisal is particularly disrupted in male patients with schizophrenia.
• Olfactory function may serve as a potential indicator of illness duration and symptom presentation in schizophrenia.