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While we all have our own criteria for deciding whether or not a particular behavior is "crazy," it's not so easy to put an accurate label on an individual. The determination of schizophrenia is a task that can only be accomplished by medical professionals, and there are many other conditions that create similar symptoms and have to be eliminated through a process called differential diagnosis:
- A person whose behaviors and communications suggest schizophrenia could be just experiencing a severe vitamin deficiency, particularly a deficiency of vitamin B1 (thiamine), which results in Korsakoff's psychosis.
- A person whose behaviors and communications suggest schizophrenia could have a congenital defect in the brain's ability to use an enzyme called methylenetetrahydrofolate reductase, which keeps it from being able to use certain B vitamins.
- This same person might have experienced damage to the brain, or infections in the brain, or various kinds of psychiatric illnesses that do not involve the delusions that are characteristic of schizophrenia. For instance, someone can be paranoid, distrustful of the world, but not a paranoid schizophrenic, distrustful of the world on the basis of a false belief. Or someone can suffer bipolar disorder, a condition that used to be known as manic-depressive disorder, without maintaining bizarre, unfounded beliefs about the world. Or a person can experience hallucinations, seeing, hearing, tasting, smelling, or feeling objects or people that aren't physically there, but realize they are hallucinations, and so not act on the sensory input.
Determining whether someone has schizophrenia or some other disorder can be a tedious, time-consuming, and expensive process.
The Israeli researchers took tissues samples from seven patients who had been diagnosed with schizophrenia and seven volunteers who did not have the disease. When the scientists cultured the nose cells in the lab, they found a specific kind of RNA in the cells grown from the tissue taken from the noses of schizophrenics that did not appear in the tissue taken from the noses of the volunteers who did not have schizophrenia.
The researchers took nose swabs because many neurological conditions, notably Alzheimer's disease, involve changes in the sense of smell, and it seemed plausible that nose tissue might undergo the same kinds of changes as brain tissue. The results of this study suggest that it is not really necessary to take samples specifically from the nose.
Called micro-RNA, or miRNA, this tiny snippet of genetic material only appears when someone has the disease. But why should the nose know that someone has schizophrenia?