SCIENCE: Heart attacks may reduce the risk of Parkinson’s disease, according to a study of more than one million people.

Some new research may have found use­ful clues, link­ing hav­ing a heart attack with a low­er risk of devel­op­ing Parkin­son’s dis­ease lat­er on.

The reduced risk is about 20%, based on an analy­sis of 181,994 patients in the Dan­ish health sys­tem who had a heart attack between 1995 and 2016, com­pared with 909,970 con­trol sub­jects, matched for age, sex and year of their heart attack diagnosis. .

In addi­tion, the risk of devel­op­ing parkin­son­ism — which caus­es the same type of move­ment dif­fi­cul­ties and oth­er symp­toms as Parkin­son’s dis­ease, although in this study not clas­si­fied as Parkin­son’s dis­ease itself — was also reduced by 28%. The researchers fol­lowed the study par­tic­i­pants for up to 21 years.

“The risk of Parkin­son’s dis­ease seems to be reduced in these patients, com­pared to the gen­er­al pop­u­la­tion,” says the first author of the new paper, epi­demi­ol­o­gist Jens Sund­bøll from Aarhus Uni­ver­si­ty Hos­pi­tal in Denmark.

This is the first time research has looked at the risk of Parkin­son’s dis­ease in heart attack sur­vivors, and it is still too ear­ly to under­stand why the risk is reduced. Heart attacks and Parkin­son’s dis­ease have a com­plex set of risk fac­tors, and it is pos­si­ble that the answer to this rela­tion­ship lies some­where with­in them.

Some clas­sic risk fac­tors for heart attacks — includ­ing smok­ing, high cho­les­terol, high blood pres­sure and type 2 dia­betes — have already been linked to a low­er risk of devel­op­ing Parkin­son’s dis­ease. These links could there­fore be the rea­son for the results observed in the new study.

How­ev­er, the oth­er risk fac­tors are the same. Heart attacks and Parkin­son’s dis­ease are more like­ly in old­er peo­ple and less like­ly in peo­ple who drink more cof­fee and are more phys­i­cal­ly active.

The new study gives doc­tors more advice on where to focus their atten­tion on peo­ple recov­er­ing from a heart attack.

“For doc­tors treat­ing patients after a heart attack, these results indi­cate that car­diac reha­bil­i­ta­tion should focus on pre­vent­ing ischaemic stroke, vas­cu­lar demen­tia and oth­er car­dio­vas­cu­lar dis­eases such as a new heart attack and heart fail­ure,” says Sundbøll.

How­ev­er, it seems that a reduced risk of Parkin­son’s dis­ease and Parkin­son­ism is one of the out­comes of a heart attack. Fur­ther stud­ies are need­ed to ascer­tain this, espe­cial­ly in more diverse racial and eth­nic groups (although this research used a large sam­ple, they were pre­dom­i­nant­ly white).

Future research also needs to con­sid­er the impact of smok­ing and high cho­les­terol on the rela­tion­ship between heart attack sur­vivors and a reduced risk of Parkin­son’s dis­ease, which was not close­ly exam­ined in this study.

“We have already found that fol­low­ing a heart attack, the risk of neu­rovas­cu­lar com­pli­ca­tions such as ischaemic stroke [stroke caused by a clot] or vas­cu­lar demen­tia is marked­ly increased, so the find­ing of a low­er risk of Parkin­son’s dis­ease was some­what sur­pris­ing,” says Sundbøll. .