Olfaction--a window to the mind.

Although our knowledge of the brain, the olfactory sense and autoimmunity continues to evolve, examining the olfaction ability is not yet routinely applied by clinicians in the process of diagnosis and treatment. Moreover, assessment of the sense of smell and olfactory impairments is usually overlooked by patients and their clinicians. Given the clinical data reviewed here, clinicians should be encouraged to screen for olfactory impairments, which can help in the early diagnosis of CNS diseases such as Parkinson, dementia and schizophrenia, as well as CNS-autoimmune diseases such as neuropsychiatric lupus.