[Olfactory dysfunctions in patients with schizophrenia]

Olfactory dysfunctions in patients with schizophrenia are becoming the aim of an increased number of studies. Smell identification deficits are well known but also other olfactory processes are examined, eg. sensitivity, discrimination, familiarity and edibility. Smell identification deficits are present in patients with schizophrenia and also in their non-psychotic siblings. Moreover, this dysfunction was reported in a group of children and adolescents with psychosis. Patients have also neuroanatomical abnormalites in brains structures linked with olfaction, e.g. olfactory bulb. Probably, there is no relationship between pathology of olfactory mucosa and olfactory dysfunction. However, correlation between smoking, neuroleptic treatment and olfactory deficits was not found, but it is unclear what is the role of long-term pharmacotherapy. There is a relationship between negative symptoms, IQ and olfactory processing. Smell identification deficits are not specific for schizophrenia. This disorder is well described in Alzheimer's disease. It is possible that olfactory deficits in schizophrenia are induced by pathology in cortical or subcortical regions which cannot be detected in neuropsychological tests. Currently it is difficult to use olfactory deficits as endophenotypical markers of schizophrenia, and further studies are necessary.