New def­i­ni­tion of Alzheimer’s changes re­search fo­cus

The Niagara Falls Review - - Arts & Life - MAYO CLINIC NEWS NET­WORK

When you think of de­men­tia, most peo­ple au­to­mat­i­cally think of Alzheimer’s dis­ease, too. But, under a new def­i­ni­tion of Alzheimer’s, the two terms no longer will be con­sid­ered in­ter­change­able.

The new def­i­ni­tion is part of a new frame­work for re­search­ing Alzheimer’s dis­ease that the Alzheimer’s As­so­ci­a­tion and the Na­tional In­sti­tute on Ag­ing de­vel­oped and re­leased.

“Alzheimer’s dis­ease is one cause of de­men­tia,” Dr. Clif­ford Jack Jr., a Mayo Clinic ra­di­ol­o­gist and Alzheimer’s re­searcher, says. “It’s the most com­mon cause, but it’s cer­tainly not the only cause. And that has been a source of ma­jor con­fu­sion.”

Jack helped lead a team of sci­en­tists with the Alzheimer’s As­so­ci­a­tion and the Na­tional In­sti­tute on Ag­ing re­leas­ing the new Alzheimer’s re­search frame­work.

Cur­rently, Alzheimer’s is di­ag­nosed by eval­u­at­ing symp­toms and cog­ni­tive be­hav­iour as­so­ci­ated with the dis­ease. But, Jack says, that can be mis­lead­ing for re­search.

So, in the new re­search frame­work, Alzheimer’s dis­ease is not di­ag­nosed based on symp­toms. In­stead, it is di­ag­nosed by its neu­ropathol­ogy, re­ferred to as plaques and tan­gles. This can be done at au­topsy or us­ing biomark­ers when a per­son is still liv­ing. That means through cere­bral spinal fluid or through brain imag­ing.

Jack says the change is sig­nif­i­cant.

“What we’re say­ing is that symp­toms are a con­se­quence of the dis­ease,” he says. “They’re not the def­i­ni­tion of the dis­ease. Peo­ple can have the pathol­ogy in the brain and be symp­tom-free. They still have the dis­ease even though they have no symp­toms. If they have the pathol­ogy, they have the dis­eases. It’s con­tro­ver­sial in some cir­cles be­cause, his­tor­i­cally, the pres­ence of symp­toms was the def­i­ni­tion. Now we’re say­ing (that’s) no longer so.”

Jack says chang­ing the def­i­ni­tion al­lows re­search to bet­ter tar­get pa­tients so clin­i­cal tri­als will be more ef­fec­tive.

He also says this change is sig­nif­i­cant be­cause it can al­low re­searchers to di­ag­nose Alzheimer’s dis­ease be­fore a pa­tient has symp­toms. This will al­low sci­en­tists to de­velop treat­ments that stop Alzheimer’s be­fore symp­toms de­velop, im­prov­ing the qual­ity of life for pa­tients.

Jack says a good way to think of the shift is com­par­ing it to how health care providers treat heart dis­ease.

“The best way to treat car­dio­vas­cu­lar dis­ease is by giv­ing an asymp­to­matic per­son statins, you know, for 20, 30 years, as op­posed to wait­ing un­til that per­son has a stroke or heart at­tack, and then try­ing to treat (that),” he says. “So that’s the ... and it’s only by defin­ing the dis­ease in this way, bi­o­log­i­cally, that you can iden­tify treat­ments that pre­vent the on­set of symp­toms.”

Jack says he and the other sci­en­tists re­leas­ing the new frame­work hope it will cre­ate a com­mon lan­guage for re­searchers to use in the short term.

“The long term is that these biomark­ers — clas­si­fy­ing peo­ple in this way, defin­ing Alzheimer’s dis­ease in this way, us­ing biomark­ers to de­ter­mine who ac­tu­ally gets into clin­i­cal tri­als — that will lead to more rapid de­vel­op­ment and iden­ti­fi­ca­tion of treat­ments,” he says. “And, so, the long term is that this biomarker-based def­i­ni­tion will lead more rapidly to ef­fec­tive treat­ments.”

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