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“Trust hormone” now tied to “mind reading”—and increasingly, autism

An unusual hor­mone has a grow­ing list of doc­u­ment­ed pow­ers, some of them sur­p­ris­ing—and int­ri­guing to sci­ent­ists hunt­ing aut­ism treat­ments.

Dec. 13, 2006
Special to World Science  

Re­search­ers in re­cent years have in­tense­ly stud­ied a hor­mone thought to be re­le­vant to aut­ism, a dis­or­der that has stirred grow­ing alarm. And the longer the scru­ti­ny of the hor­mone, ox­y­to­cin, goes on, the longer grows a list of some­times sur­pris­ing pow­ers at­tri­buted to it. These are prompt­ing sci­ent­ists to pro­pose the chem­i­cal might help treat aut­ism.

The "Read­ing the Mind in the Eyes Test" in­volves view­ing 36 pho­tos of eyes, and judg­ing which emo­tion or men­tal state each pair rep­re­sents. A ver­sion of the test can be tak­en here.

The re­ported im­p­rove­ments touched on a core feature of au­t­ism, dif­ficul­ty in at­tri­but­ing emo­tions and thoughts to others, though the re­search­ers didn’t spe­cu­late as to how much this might help al­le­vi­ate the over­all dys­func­tion.

Among oxy­tocin's doc­u­men­ted func­tions is stim­u­lat­ing the mo­ther-in­fant bond as well as milk ejec­tion dur­ing lac­ta­tion and uter­ine con­trac­tion dur­ing birth. Above, The Bath by Mary Cas­satt (1891.)

Ox­y­to­cin, pro­duced in the brain, con­sists of a type of mol­e­cule called a pep­tide.

Au­tism—brought to wide pub­lic at­ten­tion by the 1988 film “Rain Man” in which Dus­tin Hoff­man plays an au­tis­tic man—is a brain dis­or­der in­volv­ing de­fi­cits in so­cial in­ter­ac­tion and speak­ing; ina­bil­i­ty to treat oth­ers as peo­ple or make friends; un­u­su­al, re­pet­i­tive be­hav­iors; and some­times ex­traor­di­nary skills in spe­cif­ic ar­eas, of­ten in­volv­ing math or rote mem­o­ry.

Au­tism di­ag­noses have mys­te­ri­ous­ly surged in the Unit­ed States, Unit­ed King­dom and some oth­er in­dus­tri­al­ized coun­tries in re­cent years, trig­ger­ing wide­spread con­cern. Treat­ments exist that help some­what, but a cure is elu­sive.

Some ex­pe­rts have at­trib­ut­ed the increase to great­er aware­ness, but oth­ers dis­a­gree. Recent est­i­mates from the U.S. Cen­ters for Dis­ease Con­trol put the prev­a­lence of au­tism at 3.4 per 1,000. 

A mix of poor­ly un­der­stood ge­net­ic and en­vi­ron­men­tal fac­tors are be­lieved to cause the con­di­tion.

The Mount Si­nai re­search­ers worked with 15 peo­ple di­ag­nosed with ei­ther au­tism or Aspe­rger’s Syn­drome, a si­m­i­lar con­di­tion of­ten viewed as a mild form of au­tism. In the stu­dy, the pa­tients re­ceived ox­y­to­cin in­fu­sions and, on a sep­a­rate day, in­fu­sions of an in­ac­tive sub­stance for com­par­i­son.

The sci­en­tists found that both treat­ments led to bet­ter scores on a test that in­volved dis­cern­ing the emo­tional tone of pre-recorded state­ments, but the im­prove­ments lasted long­er with ox­y­to­cin treat­ment. 

A pre­vi­ous stu­dy, pub­lished in the June 2, 2005 is­sue of the re­search jour­nal Na­ture, found that a whiff of ox­y­to­cin made peo­ple more like­ly to trust some­one else to look af­ter their cash. 

Some com­men­ta­tors started to dub ox­y­to­cin the “trust hor­mone” af­ter that. But the new­est find­ings sug­gest that its pow­ers in social func­tion­ing ex­tend well be­yond trust, in­to “mind-reading” abil­i­ty as well, wrote re­search­ers with Ros­tock Uni­ver­si­ty in Ros­tock, Ger­ma­ny, in Bi­o­log­i­cal Psy­chi­a­try’s Nov. 28, 2006 ad­vance on­line edi­tion.

This group tested 30 healthy men on the “Read­ing the Mind in the Eyes Test,” which in­volves judg­ing peo­ple’s emo­tional state based on pho­tographs of their eyes. The par­ti­ci­pants sniffed ei­ther ox­y­to­cin or an in­ac­tive sub­stance, one week apart, and were found to do bet­ter with the ox­y­to­cin. 

Like the two pre­vi­ous stud­ies, it was dou­ble-blind, mean­ing in­ves­ti­ga­tors weren’t aware at any giv­en time of wheth­er par­ti­ci­pants had got­ten the real or the sham treat­ment.

“The abil­i­ty to ‘read the mind’ of oth­er in­di­vid­u­al, that is, to in­fer their men­tal state by in­ter­pret­ing sub­tle so­cial cues, is in­dis­pen­sa­ble in hu­man so­cial in­ter­ac­tion,” the re­search­ers wrote. Be­cause au­tism is char­ac­ter­ized both by low ox­y­to­cin and “by dis­tinct im­pair­ments in mind-read­ing,” they added, “ox­y­to­cin should be con­sid­ered a sig­nif­i­cant fac­tor in the path­o­gen­e­sis [cause] and treat­ment of au­tism.”

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Researchers in recent years have intensely studied a hormone believed to be linked to a disorder that is causing growing alarm, autism. And as they have scrutinized the hormone, oxytocin, they have found that it has a seemingly ever-growing list of surprising powers. Last year, one group identified it as a chemical linked to trust. Now, researchers are saying it helps with “mind reading,” the ability to gauge other people’s emotions based on subtle social cues. Oxytocin has long been known to regulate key aspects of social interactions. And autism, which involves marked difficulties in social interactions, has been linked to low oxytocin levels. Thus, authors of two recent studies have suggested the hormone might be useful in treating autism. One team also reported that oxytocin treatment improved autistic patients’ ability to detect emotion in speech. The findings “provide preliminary support for the use of oxytocin in the treatment of autism,” wrote the researchers, with the Mount Sinai School of Medicine in New York, in the Aug. 10 advance online edition of the research journal Biological Psychiatry. Oxytocin, produced in the brain, consists of a type of molecule called a peptide. Autism—brought to wide public attention by the 1988 film “Rain Man” in which Dustin Hoffman plays an autistic man—is a disorder involving deficits in social interaction and speaking; inability to treat others as people or make friends; unusual, repetitive behaviors; and sometimes extraordinary skills in specific areas, typically feats of math or rote memory. Autism diagnoses have mysteriously surged in the United States, United Kingdom and several other industrialized countries in recent years, triggering widespread alarm. Some experts have attributed the trend to greater awareness, but others disagree. The U.S. Centers for Disease Control has estimated the prevalence of autism at 3.4 per 1,000. A mix of poorly understood genetic and environmental factors are believed to contribute to the condition. The Mount Sinai researchers worked with 15 people diagnosed with either autism or Asperger’s Syndrome, a similar condition often viewed as a mild form of autism. In the study, the patients received oxytocin infusions and, on a separate day, infusions of an inactive substance for comparison. The scientists found that both treatments led to better scores on a test that involved discerning the emotional tone of pre-recorded statements, but the improvements lasted longer with oxytocin treatment. A previous study, published in the June 2, 2005 issue of the research journal Nature, had found that a whiff of oxytocin made people more likely to trust someone else to look after their cash. Some commentators started to dub oxytocin the “trust hormone” after that. But the newest findings suggest that its powers extend well beyond trust, into “mind-reading” ability as well, wrote researchers with Rostock University in Rostock, Germany, in the Nov. 28, 2006 advance online edition of Biological Psychiatry. This group tested 30 healthy men on the “Reading the Mind in the Eyes Test,” which involves judging people’s emotional state based on photographs of their eyes. The partici pants sniffed either oxytocin or an inactive substance, one week apart, and were found to do better with the oxytocin. Like the two previous studies, it was double-blind, meaning invest igators weren’t aware at any given time of whether partici pants had gotten the real or the sham treatment. “The ability to ‘read the mind’ of other individuals, that is, to infer their mental state by interpreting subtle social cues, is indispensable in human social interaction,” the researchers wrote. Because autism is characterized both by low oxytocin and “by distinct impairments in mind-reading,” they added, “oxytocin should be considered a significant factor in the pathogenesis [cause] and treatment of autism.”