March 07, 2007

Chemical in Sweat and Inability to Smell it May be Schizophrenia Marker

Some people with chronic schizophrenia characterized by predominantly disorganized and negative symptoms have been found to have an unusual, specific odor to their sweat and they have also been found to have impairment detecting certain odors.

PsychiatryMatters.MD has reported on results from an Australian study, published in journal Psychiatry Research, which examined the link between these two findings.

The chemical exuded in the sweat of these patients with chronic schizophrenia causing the distinct odor is a chemical called trans-3-methyl-2-hexenoic acid (MHA). The study found that the group of patients with chronic schizophrenia could not detect that chemical odor as well as the study group without schizophrenia, nor as well as the study group with just first-episode psychosis.

Further study is needed to determine if the reduced olfactory sensitivity to the chemical (ability to smell it) is due to olfactory habituation effects (we tend to not be as sensitive to a smell which we are constantly exposed to), abnormal chemical processing or a genetic predisposition.

Other scents tried, such as some pheromones and cleaning fluid, could be detected equally by all three groups.

The team noted that:

In patients with chronic schizophrenia, reduced sensitivity to MHA correlated significantly with the severity of disorganized and negative symptoms.

"The results confirm that olfactory identification deficits... occur in the presence of relatively intact acuity for traditionally used substances," the authors conclude.

It is hoped that this chemical in the sweat, as well as the olfactory sensitivity to it may help in early diagnosis, and possibly be another direction for genetic and biological research into the understanding of this type of schizophrenia.

Read the full article: Olfactory sensitivity impaired in chronic schizophrenia

Original Source Abstract: Olfactory sensitivity through the course of psychosis: Relationships to olfactory identification, symptomatology and the schizophrenia odour (Psychiatry Res 2007; 149: 97-104)

Additional Information: A Smell Test for Diagnosing Schizophrenia Before the Onset of Symptoms

Further Reading:
Smell Deficits a possible marker for Schizophrenia susceptibility
Nose Cells Provide Disease Insight
Smell test 'spots schizophrenia'


That abstract claims otherwise. But it is from the 70's, so who knows.

Posted by: CorySchulz at March 7, 2007 11:40 AM

That study from the 70s that did not find it elevated in the sweat of people with schizophrenia might be an example of studying "schizophrenia" as one illness instead of the multitude of illnesses that it apparently is. That study, as far as I can tell, did not separate out types of schizophrenia. The newer studies of this chemical in sweat are studying it in those for whom it possibly is a biomarker - finding that the ones that do have it in abundance are also the ones who have an abundance of negative, as opposed to positive, symptoms, and disorganized thinking.

I actually wish researchers did this sort of studying more - for instance instead of lumping everyone together and saying, "vitamin supplements don't help", figure out why the ones that it does help are helped, why that sub-group needs the supplements, and figure out if they can tell up-front which ones will benefit.

Better yet, I hope that some day medical science will have a different diagnosis for each subgroup currently getting labled "schizophrenia" with distinct treatment protocols for each distinct diagnosis. Right now - the diagnosis is made on a vast set of symptoms. At one time, other endocrinological illnesses had those symptoms, thus were getting lumped into that same bucket. Perhaps someday the subgroup with the elevated excretion of this chemical in their sweat will become a separate diagnosis and have a treatment formulated specifically for their needs.


Posted by: Jeanie at March 7, 2007 01:11 PM

Yes, I think right now any major reality altering malfunction in the brain that is dopamine related is being thrown into the 'schizophrenia bucket' without further organization. It is definitely clear that many schizophrenic patients have distinctly different mental symptoms and have a variety of responses to the medications available.

In the last 30+ years our technology and understanding of mental disease has grown quite a bit, so I have no doubt that these previous studies are outdated or obsolete.

Posted by: Cory Schulz at March 7, 2007 07:27 PM

Sweat,in certain forms of schizophrenia, eg paranoid schizophrenia,can smell fairly awful.This was one of the first complaints of my son who went on to develop paranoid schizophrenia. However, I would recommend to the scientists involved in this research to take a closer look at the near relatives of the patient as they may find a similar set of complaints ie smelly sweat.etc.I, for instance, find it difficult to process certain foods,particularly white fish,without a horrid smell in my sweat and urine the next day. Perhaps there is some genetic malfunction in the way we process certain foods-just a thought.

Posted by: jo newberry at March 14, 2007 01:28 PM

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