46 | New Scientist | 6 November 2021Features
Piecing it together
A new approach to Alzheimer’s disease is changing how we search for its cause,
and could finally give us effective treatments, finds Hannah Thomasy
F
OR the first time in nearly two decades,
a new treatment for Alzheimer’s disease
was approved by the US Food and Drug
Administration in June. But instead of joy and
relief, the announcement was largely met with
frustration and even anger. Some experts
pointed out that the clinical trial that was the
basis of approval for Biogen’s drug aducanumab
didn’t conclusively show that it reduced
cognitive decline. Instead, the FDA based its
unprecedented decision on evidence that the
drug treats the underlying cause of Alzheimer’s.
The trouble is, it is far from clear that the
target of this drug – clumps of beta-amyloid
protein – is truly the cause. Drugs aimed at
beta-amyloid have failed time and time again.
Large-scale clinical trials representing billions
of dollars of research have shown no positive
impact; some experimental medicines even
seemed to make cognition worse.
With this new drug, there were also concerns
about the FDA approval process. Ultimately,
the agency’s acting commissioner Janet
Woodcock requested an investigation into
her own agency’s decision-making.
But the controversy isn’t limited to this
decision. The big worry is that the continued
focus on beta-amyloid is a dangerous
distraction, that it may actually obscure the
complex nature of the disease and waste
precious time. The growing consensus is that
there is no single cause of Alzheimer’s, but a
complex web of contributing factors. That may
not seem like good news, but there is a silver
lining: many different factors can provide
many paths for treatment.The only way is amyloid
Worldwide, there are 10 million new cases of
dementia every year – and roughly two-thirds
of these are Alzheimer’s disease. Staggering
sums of money have been invested to try
to understand the underlying cause, with
much of the focus on one explanation.
Initially, there was good reason for that.
PEThe amyloid hypothesis gained popularity
TE
R^ S
TR
AIN