Science slowly un­folds what mi­graines are

Re­searchers are closer to un­der­stand­ing why women get more mi­graines than men, re­ports Wendy Zuk­er­man

The Weekend Australian - Travel - - Health -

EVER had a headache — a re­ally bad one that swept you right off your feet and into bed? Amy Lorimer, a 19-yearold nurs­ing and para­medic stu­dent at Monash Univer­sity started get­ting mi­graines when she was six.

‘‘ I lose the feel­ing in my hands; one side of my face tin­gles and on the other side I get a re­ally bad headache,’’ she ex­plains. ‘‘ My tongue goes numb, I am nau­seous, I of­ten throw up, and I be­come re­ally sen­si­tive to light.’’ It sounds bad, and it is — and new re­search shows that it’s more com­mon that many peo­ple would re­alise.

A study pub­lished last month in the Med­i­calJour­nalofAus­tralia re­ported that 11.5 per cent (649 out of 5663) of Aus­tralian pa­tients who went to the doc­tor in a twom­onth pe­riod suf­fered from mi­graine (2007;187;142-146). The re­port also found that women in Aus­tralia are ap­prox­i­mately three times more likely to get mi­graines than men, which is con­sis­tent with world­wide fig­ures.

As­so­ci­ate Pro­fes­sor Richard Stark, a clin­i­cal neu­rol­o­gist at the Al­fred Hospi­tal in Melbourne and co-au­thor of the re­port, says that be­cause the sub­jects of his study were pa­tients who were visit­ing a doc­tor, Aus­tralians who haven’t been di­ag­nosed wouldn’t be ac­counted for.

‘‘ A lot of peo­ple who have mi­graine don’t recog­nise that it is mi­graine,’’ Stark says. ‘‘ On the other hand, there is a group of peo­ple who get re­ally bad mi­graine, and feel cheated when peo­ple un­der­value how de­bil­i­tat­ing they are.’’

In the study Stark spec­u­lated that, like many of us, GPs can un­der­es­ti­mate the ef­fect that fre­quent mi­graines have on pa­tients.

Lorimer un­der­stands this feel­ing more than most. When she tells peo­ple she suf­fers from mi­graine — a pa­tient some­times re­ferred to as a mi­graineur — the usual re­sponse is: ‘‘ I get mi­graines, too’’.

Nadia Matthies­son, a part-time of­fice man­ager and fel­low mi­graineur, says she never tells peo­ple she suf­fers from mi­graine. ‘‘ The re­sponse is ei­ther ‘ Oh, I get them’, or they think ‘ Oh, it’s one of those’,’’ she says.

Doc­tor Dale Ny­holt, of Grif­fith Univer­sity, has stud­ied the causes and af­fects of mi­graine in Aus­tralia for a decade. He be­lieves that mi­graine is ‘‘ def­i­nitely’’ mis­un­der­stood by the Aus­tralian com­mu­nity. Ny­holt says mi­graine has a range of di­rect med­i­cal and in­di­rect eco­nomic costs to in­di­vid­ual suf­fer­ers as well as to the gen­eral com­mu­nity.

He cal­cu­lates that the to­tal cost of mi­graine to the Aus­tralian com­mu­nity could be over $1 bil­lion per year, once med­i­cal con­sul­ta­tions, drug treat­ment, lost pro­duc­tiv­ity in the work­place and ab­sen­teeism are all fac­tored in.

Clearly, this is more than can be cured with a parac­eta­mol and a glass of wa­ter.

In Matthies­son’s case, on two oc­ca­sions the throb­bing from her headaches was so bad she had to be ad­mit­ted to hospi­tal: ‘‘ The pain was so in­tense, it fright­ened me’’.

When Lorimer’s mi­graine at­tacks are at their worst, she can’t read be­cause fo­cus­ing on small print in­ten­si­fies her headaches. Work­ing with com­put­ers or even work­ing with lights, es­pe­cially flu­o­res­cent lights, is im­pos­si­ble. ‘‘ I can’t do it — I just can’t,’’ she says.

De­spite mod­ern medicine, the best rem­edy for Lorimer’s mi­graines is turn­ing off the lights and ly­ing in bed in com­plete si­lence.

Matthies­son started get­ting mi­graines when she was eight years old. ‘‘ At that stage they didn’t call it mi­graine, they just thought you were sick — they didn’t re­alise what it was,’’ she says. Only in her late teens did doc­tors be­gin di­ag­nos­ing her con­di­tion as mi­graine.

So, what is mod­ern medicine say­ing about mi­graine now? And why are they more com­mon in women?

This year, a re­view pub­lished in Phar­ma­col­ogy & Ther­a­peu­tics (2007;113;321-340) re­ported that fe­male sex hor­mones like es­tro­gen could ac­count for the preva­lence of mi­graine in women. Mi­graines are thought to be caused by blood ves­sels in the brain ex­pand­ing and ac­ti­vat­ing nerves, which then stim­u­late pain re­cep­tors. Hor­mones, which are found in the blood, can in­crease and de­crease the size of blood ves­sels. Plus, es­tro­gen in­ter­acts with pain re­cep­tors around the ar­ter­ies that sur­round the brain, and this could ex­plain the throb­bing felt dur­ing a mi­graine at­tack.

Whilst gen­eral grog­gi­ness dur­ing a wo­man’s pe­riod is one thing, a re­port in Neu­rol­ogy (2004;63:351) found 60 per cent of fe­male mi­gra­neurs re­port at­tacks around their men­strual cy­cle, a time when there is a dra­matic change in fe­male hor­mone lev­els. In ad­di­tion, hor­mone con­tra­cep­tives, which con­tain es­tro­gen-like chem­i­cals, have been con­sis­tently shown to af­fect the fre­quency and in­ten­sity of mi­graines. Stud­ies show male-tofe­male trans­sex­u­als, who take hor­mone sup­ple­ments, have an in­creased in­ci­dence of mi­graines since treat­ment.

Lorimer is the per­fect poster child for th­ese sci­en­tific the­o­ries. The week be­fore her pe­riod she would get ‘‘ hor­rific headaches’’, and her mother ex­pe­ri­enced con­stant at­tacks when she was preg­nant (when fe­male sex hor­mone lev­els in­crease).

Stark sup­ports the the­ory that hor­mones are a ma­jor cause of mi­graine. ‘‘ We know that the in­ci­dence of mi­graine in women is higher than men be­tween teenage years and menopause,’’ he says. Be­fore or af­ter that time pe­riod, the amount of men and women suf­fer­ing from mi­graine ‘‘ is fairly equal’’.

Un­for­tu­nately, stud­ies on the ef­fect of hor­mones on mi­graineurs are in­con­sis­tent. Some show oral con­tra­cep­tives worsen symp­toms, while oth­ers show women are less likely to suf­fer from mi­graine when on the pill.

Lorimer takes a pro­ges­terone-only form of con­tra­cep­tive as pre­ven­ta­tive treat­ment for her mi­graines, which helps re­duce the at­tacks. But Matthies­son can’t at­tach any hor­monal ex­pla­na­tion to her headaches. It seems that the ef­fect of hor­mones on mi­graine is as in­di­vid­ual as men­stru­a­tion it­self.

Ev­i­dence sug­gests that ge­netic fac­tors play an im­por­tant role in mi­graine. Ny­holt ex­plains that stud­ies of iden­ti­cal twins ‘‘ in­di­cate that mi­graine has a sig­nif­i­cant ge­netic com­po­nent’’. Stark says peo­ple ‘‘ are born with a sus­cep­ti­bil­ity to mi­graine, and the cause is pre­dom­i­nantly ge­netic’’.

Lorimer’s grand­mother, mother and sis­ters all suf­fer from mi­graine. How­ever, Matthies- son is the only suf­ferer in her fam­ily.

Nearly 10 years ago Ny­holt pub­lished an ar­ti­cle in Hu­man Molec­u­lar Ge­net­ics (1998;7;459-463) propos­ing that there was a gene on the X chro­mo­some that pre­dis­posed peo­ple, es­pe­cially women, to mi­graine. Be­cause women have two X chro­mo­somes, com­pared to men who only have one, it made sense that women would have a higher chance of get­ting mi­graines.

In a study of the DNA of 103 Aus­tralians from three large fam­i­lies he found sev­eral genes on the X chro­mo­some that were po­ten­tial sites for the ‘‘ mi­graine gene’’. But Ny­holt now be­lieves we will have a de­fin­i­tive an­swer to whether there is a mi­graine gene on the X chro­mo­some in a year or two.

Stark says there is very likely to be a gene in the X chro­mo­some, but there are likely to be genes on other, non-gen­der-spe­cific chro­mo­somes. It looks like the X chro­mo­some is not the X-fac­tor ex­plain­ing why women are more af­fected by mi­graines than men.

The most dif­fi­cult part about study­ing mi­graines is the in­con­sis­tent symp­toms of mi­graineurs, which makes it tricky to di­ag­nose and in­ves­ti­gate the dis­ease. Re­search is clearly show­ing that there is a sci­en­tific ba­sis to ex­plain why women suf­fer from mi­graines more than men. The re­search also shows that mi­graines aren’t just de­hy­dra­tion headaches that some peo­ple can’t han­dle; they are de­bil­i­tat­ing and af­fect in­di­vid­u­als world­wide.

Pic­ture: David Crosling

Crip­pling: Amy Lorimer’s blind­ing headaches com­pletely dis­able her

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