Odor Perception and Neuropathology in Neurodegenerative Diseases and Schizophrenia

This chapter is a review of what is known about the olfactory function of a range of neurodegenerative diseases and schizophrenia (SZ). It deals with diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis, down syndrome, essential tremor, Huntington's disease (HD), and idiopathic rapid eye movement sleep behavior disorder. Some of the other diseases discussed here include Lewy body disease (LBD), Parkinson's disease (PD), progressive supranuclear palsy, pure autonomic failure, schizophrenia, spinocerebellar ataxias, temporal lobe epilepsy, and vascular dementia. It is noteworthy that a number of neurological disorders are accompanied by no, or only modest, alterations in smell function. It is important to note that several studies of AD and SZ patients have reported lack of significant effects on odor detection threshold tests, in contrast to highly significant effects on such tests as the University of Pennsylvania Smell Identification Test (UPSIT).