Page 28 - aruba-today-20190911

A28 SCIENCE
Wednesday 11 september 2019
Scientists rethink Alzheimer’s, diversifying the drug search

By LAURAN NEERGAARD gue that these cells are sort
AP Medical Writer of a missing link.”
WASHINGTON (AP) — Separately, biotech com-
When researchers at the pany Alector Inc. has be-
University of Kentucky gun first-step patient test-
compare brains donated ing of a drug designed to
from people who died with boost TREM2 and better
dementia, very rarely do activate microglia.
they find one that bears THE GERM CONUNDRUM
only Alzheimer’s trademark Could gum disease or her-
plaques and tangles — no pes be to blame? The idea
other damage. that infections earlier in life
If they do, “we call it a uni- could set the stage for Al-
corn,” said Donna Wilcock, zheimer’s decades later
an Alzheimer’s specialist at has simmered on the edge
the university’s aging cen- of mainstream medicine,
ter. Contrary to popular but it’s getting new atten-
perception, “there are a lot tion.
of changes that happen in It sounds weird, but both
the aging brain that lead the germ that causes gum
to dementia in addition to disease and different strains
plaques and tangles.” of herpes viruses have
That hard-won lesson helps been found in Alzheimer’s-
explain how scientists are affected brain tissue.
rethinking Alzheimer’s. Researchers in New York
For years researchers have In this Aug. 14, 2019 photo provided by the University of Kentucky, Donna Wilcock, of the Sanders- are testing the herpes drug
been guided by one lead- Brown Center on Aging, holds a brain in her lab in Lexington, Ky. valacyclovir in 130 people
ing theory — that getting rid Associated Press with mild Alzheimer’s who
of a buildup of a sticky pro- doctors at Barrow Neuro- ing tangles inside neurons, One microglial job is to have evidence of infection
tein called amyloid would logical Institute in Phoenix heralding cell death and gobble up toxic proteins with certain herpes strains.
ease the mind-robbing dis- announced they had im- memory loss. and cellular debris. Recent- And Cortexyme Inc. is en-
ease. Yet drug after drug planted a pacemaker-like But again, not always: Au- ly, a mutation in a gene rolling more than 500 early-
has failed. They might clear “deep brain stimulation” topsies show sometimes called TREM2 was found stage patients around the
out the gunk, but they’re device into the first of more people die with large to weaken microglia and country to test a drug that
not stopping Alzheimer’s in- than 200 patients for an in- amounts of both plaques increase the risk of Alzheim- targets potentially neuron-
evitable worsening. ternational study . and tangles, yet escape er’s. Dr. David Holtzman at damaging substances pro-
The new mantra: diversify. Most of the fresh starts for dementia. Washington University in St. duced by gingivitis bacte-
With more money — the drugs are in the earliest re- So something else — may- Louis took a closer look — ria.
government had a record search stages. be several other things — and says microglia may be Whether the germ theory
$2.4 billion to spend on Al- It’s far from clear that any also must play a role. One key to how the amyloid-tau is a worthwhile pursuit was
zheimer’s research this year will pan out, but “the field possible culprit: The brain’s duo turns toxic. hotly debated at an inter-
— the focus has shifted to is now much more open- unique immune cells, In donated human brains, national Alzheimer’s As-
exploring multiple novel minded than it ever was to called microglia (my-kroh- his team found more tau sociation meeting in July.
ways of attacking a dis- alternative ideas,” Wilcock GLEE’-ah). tangles clustered around One skeptic, Dr. Todd Gol-
ease now considered too said. No surprise if you’ve never amyloid plaques when de of the University of Flor-
complex for a one-size-fits- BREAKING THE PLAQUE AND heard of microglia. Neu- people harbored microg- ida, cautioned that germs’
all solution. TANGLE LINK rons are the brain’s rock lia-weakening TREM2 mu- mere presence doesn’t
On the list, researchers are No one knows what causes stars, the nerve cells that tations. mean they caused de-
targeting the brain’s spe- Alzheimer’s but amyloid de- work together to transmit The researchers altered mentia — they could be a
cialized immune system, posits were an obvious first information like memo- the TREM2 gene in mice consequence of it.
fighting inflammation, even suspect, easy to spot when ries. Microglia are part of and seeded their brains Still, a 2018 study from Tai-
asking if simmering infec- examining brain tissue. But a different family of cells with a little human tau. wan offered a hint that
tions play a role. it turns out that gunk starts long regarded as the neu- Sure enough, more tangles treating herpes infection
Some even are looking be- silently building up 20 years rons’ support staff. But “it’s formed next to plaques in might lower later dementia
yond drugs, testing if electri- before any memory loss, becoming clear they’re mice with weak microglia risk. And a U.S. study found
cal zaps in the brain, along and by itself it’s not enough much more active and than in those with func- certain herpes viruses af-
a corridor of neural con- to cause degeneration. play a much more signifi- tional immune cells, they fected the behavior of Al-
nections, might activate it Sometime after plaques cant role,” said Dr. Richard recently reported in Nature zheimer’s-related genes.
in ways that slow Alzheim- appear, another protein Hodes, director of the Na- Neuroscience. “Maybe these are just op-
er’s damage. Tuesday, named tau starts form- tional Institute on Aging. Why? Normal microglia portunistic pathogens that
seem to restrict amyloid have space to spring up
plaques, which limits dam- in the brains of people af-
age to surrounding tissue — fected with Alzheimer’s dis-
damage that can make it ease,” said Benjamin Read-
easier for tau to take hold, head of Arizona State Uni-
he explained. versity, who co-authored
While it was known that that U.S. paper.
amyloid buildup drives tau But, “it looks at least plau-
tangles, “we never had a sible that some of these
good clue as to how it is pathogens are capable of
doing that,” Holtzman said. acting as accelerants of
The new findings “would ar- disease.”q