''trans''-3-Methyl-2-hexenoic acid (TMHA) is an unsaturated

short-chain fatty acid Short-chain fatty acids (SCFAs) are fatty acids of two to six carbon atoms. The SCFAs' lower limit is interpreted differently, either with one, two, three or four carbon atoms. Derived from intestine, intestinal microbe, microbial fermentation of ...

that occurs in

sweat Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and Apocrine sweat gland, apocrine glands. The eccrine sweat glands are distribu ...

secreted by the

axilla The axilla (: axillae or axillas; also known as the armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm a ...

ry (

underarm The axilla (: axillae or axillas; also known as the armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and ...

)

apocrine Apocrine () is a term used to classify the mode of secretion of exocrine glands. In apocrine secretion, secretory cells accumulate material at their apical ends, often forming blebs or "snouts", and this material then buds off from the cells ...

glands of Caucasians and some Asians.

Hexanoic acid Caproic acid, also known as hexanoic acid, is the carboxylic acid derived from hexane with the chemical formula . It is a colorless oily liquid with a fatty, cheesy, waxy odor resembling that of goats or other barnyard animals. It is a fatty acid ...

s such as TMHA have a hircine odor. Of the

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

s contributing to Caucasian men's underarm odor, TMHA has the most prominent odor.

Schizophrenia odor

It has long been claimed that

schizophrenia Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, f ...

patients exhibit a particular peculiar body odor, and it has been postulated the odor may be caused by underlying metabolic abnormalities associated with the condition, among other factors. Initial studies identified the causal component as TMHA, however, subsequent studies failed to reproduce such results, with subsequent researchers suggesting the initial research may have had misidentified impurities in samples as TMHA due to poor methodology. However, a 2007 study found schizophrenia patients to have reduced olfactory sensitivity to TMHA, possibly indicating sensory

habituation Habituation is a form of non-associative learning in which an organism’s non-reinforced response to an inconsequential stimulus decreases after repeated or prolonged presentations of that stimulus. For example, organisms may habituate to re ...

; the decreased ability to smell the substance due to the presence of the substance as a constant component of subjects' own sweat and body odor. Furthermore, the researchers noted a positive association between reduced ability to smell TMHA and greater severity of disorganised and negative symptoms. An allusion to TMHA and its purported link to the smell of the mentally ill is made in the 1996

David Foster Wallace David Foster Wallace (February 21, 1962 – September 12, 2008) was an American writer and professor who published novels, short stories, and essays. He is best known for his 1996 novel ''Infinite Jest'', which ''Time (magazine), Time'' magazine ...

novel, '' Infinite Jest'', and in the 1988 novel '' The Silence of the Lambs'' by

Thomas Harris William Thomas Harris III (born September 22, 1940) is an American writer. He is the author of a series of suspense novels about Hannibal Lecter. The majority of his works have been adapted into films and television, including '' The Silence o ...

References

{{DEFAULTSORT:Methyl-2-hexenoic acid, trans-3- Fatty acids Enoic acids