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A man whose genetics almost guaranteed that he would develop Alzheimer ’s disease by his 50s has somehow made it to his mid-70s with nary a symptom .
The now-75 - yr - one-time world , Doug Whitney , is one of only three masses eff to have escaped their genetic fate , sidestepping a rare form ofAlzheimer ’s diseasecalled dominantly inherited Alzheimer ’s disease ( DIAD ) . because of several gene variation , DIAD make up less than 1 % of all Alzheimer ’s cases , and its symptoms typically set in between ages 35 and 55 .
A 75-year-old man’s genetics should have led to him developing early Alzheimer’s decades ago. But as of yet, he has no symptoms of the disease.
A fresh study , published Feb. 10 in the journalNature Medicine , details Whitney ’s case and pinpoint potential factor that may have harbor him from the neurodegenerative disorder thus far . One hypothesis is that his pic to very high heat as a shipboard mechanic could have somehow contribute to this resiliency , co - lead authorDr . Jorge Llibre - Guerra , an assistant professor of neurology at the Washington University School of Medicine in St. Louis and co - first author of the study , told Live Science .
This report adds to the handful of case that are " potentially , a critical reference for understanding molecular mechanics that can decelerate or stave off Alzheimer ’s disease pathogenesis,“Dr . Michael Greicius , an Alzheimer ’s researcher at Stanford University who was not involved in the study , say Live Science in an email .
Related : A mankind ’s rarified gene variation may have shielded him from devastating shape of early Alzheimer ’s
A “shocking” surprise
Whitney told the research squad that he think he was one of the few who had escaped the mutations that had cause so much DIAD in his syndicate . At age 61 — when Whitney first approached the researchers about enrolling in a large visitation about DIAD — he register no sign of the zodiac of Alzheimer ’s disease , whereas his mother and 11 of her 13 siblings had developed the consideration by the time they were in their 50s .
DIAD is do by mutations in three genes : amyloid herald protein ( APP ) , presenilin-1 ( PSEN1 ) or presenilin-2 ( PSEN2 ) . The overwhelming bulk of people with DIAD only carry one of these chromosomal mutation , although Llibre - Guerra said he ’s occur across a few who carried more than one .
" Once you inherit some of these mutations , you have like a 99.99 % fortune of developing the disease , " Llibre - Guerra allege . That ’s why Whitney was " shocked " to see that he express a sport in the PSEN2 gene that should have head to early - onset Alzheimer ’s , he added .
Now , at 75 , Whitney still has n’t develop symptoms of the condition , which makes him one of three people known to have escaped near - sure DIAD , per the study .
To understand Whitney ’s apparent protection , Llibre and his colleagues used brain scans to look for the telltale sign of Alzheimer ’s — namely , abnormal protein clumps call in amyloid - beta plaques and tau protein tangles .
The accumulation of amyloid - beta plaques is an early footmark in the development of Alzheimer ’s disease , accompany by an accumulation of " maze " of tau protein . Evidence suggeststhe interplay between these two proteins is potentially what lead to cognitive decline , although thesemay not be the only broker at play .
Whitney ’s mentality become out to be flooded with amyloid , but unlike in other DIAD patients , the tau had stayed contained within a small-scale section of the brain . These tangles were at the back of his skull , in his left occipital lobe .
This rule adds weight to the musical theme that " if we prevent the downstream effects of amyloid - beta , we might delay the onset of the disease , " Llibre - Guerra said . In other row , it seems like the chemical chain reaction between amyloid and tau was somehow broken in Whitney ’s brain . " The question that we have is , what is keep tau spread in this fussy typeface ? " he added .
This observation ring what had previously been seen in another DIAD " escapee " who also had a mutation in the PSEN1 gene , Jean - Charles Lambert , an Alzheimer ’s researcher from the Inserm Institute at the University of Lille who was not involved in the written report , tell Live Science in an email .
Could extreme heat have been protective?
A few gene variant are be intimate to protect against Alzheimer ’s . One exercise is the so - calledE2 allele of the APOE gene , which is associated with a very low risk of developing the disease , Lambert said .
But the squad did not get any of these known form in Whitney ’s inherited makeup . Instead , they pinpointed several other variants that could be interesting to canvas in the circumstance of Alzheimer ’s . These let in one variant spotted inGPCPD1 , a gene recently tie to Alzheimer ’s resilience . Another version , found in theCD33 gene , could justify further enquiry , Llibre - Guerra pronounce , as it ’s need in immune reception in the brain .
The scientist also plant high - than - normal levels of " hotness - shock proteins " in Whitney ’s intellectual spinal fluid , the liquid that cushions the brain and spinal corduroy . Heat - shock protein help protect the body from environmental stresses , such as extreme high temperature , and could be link to Whitney ’s time working as a shipboard grease monkey in boiling engine way , the squad suggested .
" We know that these protein are involved in forbid misfolding proteins in the mental capacity , " Llibre - Guerra said . Like origami , proteins must be folded in a finical path to work , and Alzheimer ’s is a disease in which this fold goes haywire . " mayhap it ’s forbid more tau from being misfolded and spreading , " Llibre - Guerra suggested , impart that this is " just a hypothesis " at this stage .
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For Lambert , this explanation is " extremely speculative , " as the evidence to back it is still very provisionary . Greicius impart that there are " countless other potential explanation " for Whitney ’s resilience against Alzheimer ’s , although this is an " interesting and plausible hypothesis . "
The squad ’s genetic investigating was a " sane first analytic thinking , " but it could have entrust " G of potentially protective discrepancy unexamined on the cutting - elbow room flooring , " Greicius added . And because this was a case study of only one person , it ’s challenge to describe a genetic variance or environmental exposure that may have helped him , he said .
Still , Greicius said , studies like this one are " useful for generating novel hypothesis . "
This clause is for informational determination only and is not mean to offer aesculapian advice .
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