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Researchers explore amnesia, sex link

Sept. 29, 2008
World Science staff

Grow­ing ev­i­dence sug­gests a puz­zling rela­t­ion­ship be­tween sex­u­al in­ter­course and a tem­po­rary am­ne­sia that oc­ca­sion­ally en­sues, re­search­ers say.

In a new stu­dy, doc­tors at the Uni­ver­s­ity Hos­pi­tal of Puerta de Hi­erro, Spain, de­scribed six such cases, in­volv­ing men and wom­en be­tween 42 and 60 years of age, that passed through their in­sti­tu­tion.

The pre­cise mech­a­nisms be­hind the sex-am­ne­sia link “are un­known,” they wrote, de­scrib­ing the cases in the Sept. 16-30 is­sue of the Span­ish-lan­guage re­search jour­nal Re­vista de Neu­rolo­gia. But a rela­t­ion be­tween the two oc­cur­rences “ap­pears in­creas­ingly more of­ten in the lit­er­a­ture… We draw at­ten­tion to the need to take sex­u­al ac­ti­vity in­to ac­count” as a pos­si­ble cause for the dis­or­der.

The am­ne­sia usu­ally goes away with­in a few hours, so “re­as­sur­ance, based on clear di­ag­no­sis, is the most im­por­tant treat­men­t,” wrote A.J. Larner of the Cen­tre for Neu­rol­o­gy and Neu­ro­sur­gery in Liv­er­pool, U.K., in a study pub­lished in the Feb­ru­ary is­sue of the Jour­nal of Sex­u­al Med­i­cine.

The form of am­ne­sia in ques­tion is called tran­sient glob­al am­ne­sia. It is de­fined as a pass­ing ep­i­sode of short-term mem­o­ry loss with­out oth­er signs or symp­toms of neu­ro­lo­g­i­cal im­pair­ment. Pa­tients are un­able to ab­sorb any new in­forma­t­ion dur­ing the ep­i­sodes, and some­times tem­po­rarily for­get some of the past as well.

The pa­tients seen at the Uni­ver­s­ity Hos­pi­tal—four men and two wom­en—were brought there about 30 min­utes to two hours af­ter hav­ing sex, the physi­cians wrote. Their am­ne­sias lasted from two to six hours, dur­ing which the pa­tients dis­played symp­toms such as ask­ing the same ques­tions re­peat­edly de­spite hav­ing re­ceived an­swers.

Many oth­er causes be­hind tran­sient glob­al am­ne­sia have been de­scribed, the re­search­ers wrote, in­clud­ing pain, anx­i­e­ty, changes in tem­per­a­ture, ex­er­cise, di­ag­nos­tic test­ing and long-dis­tance flights.

The first pub­lished med­i­cal re­ports of a sex-am­ne­sia link came in 1979, said the Span­ish re­search­ers; a few doz­en ad­di­tion­al cases have been de­scribed since then. The steadily build­ing num­ber, they wrote, “makes one sup­pose that it is not as un­com­mon as gen­er­ally be­lieved.”

Larner wrote that the am­ne­sias probably are due to a dis­rup­tion of blood flow in the brain, but more pre­cise ex­plana­t­ions have been lack­ing. The Span­ish re­search­ers not­ed that in four of the six cases they stud­ied, pa­tients suf­fered from high cho­les­ter­ol, high blood pres­sure or both.

Re­search­ers with the Uni­ver­s­ity of Gen­oa, It­a­ly, sug­gested in the Oc­to­ber 2003 is­sue of the jour­nal Neu­ro­lo­g­i­cal Sci­ences that in two cases they had stud­ied, the pop­u­lar erectile-dysfunction drug Silde­nafil, or Vi­a­gra, may have been in­volved. The drug works by ex­pand­ing blood ves­sels.

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Growing evidence suggests a puzzling relationship between sexual intercourse and a temporary amnesia that occasionally ensues, researchers say. In a new study, doctors at the University Hospital of Puerta de Hierro, Spain, described six such cases, involving men and women between 42 and 60 years of age, that had passed through their institution. The precise mechanisms behind the sex-amnesia link “are unknown,” they wrote, describing the cases in the Sept. 16-30 issue of the Spanish research journal Revista de Neurologia. But a relation between the two occurrences “appears increasingly more often in the literature… We draw attention to the need to take sexual activity into account as a possible precipitating factor in patients suffering from this disorder.” The amnesia usually goes away within a few hours, so “reassurance, based on clear diagnosis, is the most important treatment,” wrote A.J. Larner of the Centre for Neurology and Neurosurgery in Liverpool, U.K., in a study published in the February issue of the Journal of Sexual Medicine. The form of amnesia in question is called transient global amnesia. It is defined as a passing episode of short-term memory loss without other signs or symptoms of neurological impairment. Patients are unable to absorb any new information during the episodes, and sometimes temporarily forget some of the past as well. The patients seen at the University Hospital—four men and two women—were brought there about 30 minutes to two hours after having sex, the physicians wrote. Their amnesias lasted from two to six hours, during which the patients displayed symptoms such as asking the same questions repeatedly despite having received answers. Many other precipitating factors behind transient global amnesia have been described, the researchers wrote, including pain, anxiety, changes in temperature, exercise, diagnostic testing and long-distance flights. The first published medical reports of a sex-amnesia link came in 1979, said the Spanish researchers; a few dozen additional cases have been described since then. The steadily building number, they wrote, “makes one suppose that it is not as uncommon as generally believed.” Larner wrote that the amnesias probably are due to a disruption of blood flow in the brain, but more precise explanations have been lacking. The Spanish researchers noted that in four of the six cases they studied, patients suffered from high cholesterol, high blood pressure or both. Researchers with the University of Genoa, Italy, suggested in the October 2003 issue of the journal Neurological Sciences that in two cases they had studied, the popular erectile-dysfunction drug Sildenafil, or Viagra, may have been involved. The drug works by expanding blood vessels.