The Economist March 12th 2022 Science & technology 69MedicaltechnologyThe nose knows
P
arkinson’sdisease is a progressive
neurological disorder caused by the
deaths of neurons in parts of the brain
called the substantia nigra. Symptoms in
clude loss of motor control, mood distur
bance, ruined sleep and altered sense of
smell. It is incurable. Early medical inter
vention can, however, relieve these symp
toms and prolong survival. That makes
prompt diagnosis desirable.
Unfortunately, the initial signs of Par
kinson’s vary from person to person and
there is no specific test at this early stage
which can reliably distinguish it from oth
er brain illnesses. It therefore often goes
undetected until clear and characteristic
manifestations, such as tremors and
slowed body movement, appear. But that
may soon change. A study published in acs
Omega, by Chen Xing and Liu Jun at Zhe
jiang University, in China, describes an in
vention which may be able to detect Par
kinson’s before the onset of tremulous
ness. The device in question is an artificial
ly intelligent electronic nose.A whiff of trouble
The quest the two researchers embarked
on to build this nose began in 2019. That
was when they heard reports of Joy Milne, a
retired nurse living in Scotland, who could
detect people with Parkinson’s from a dis
tinctive odour they emitted—distinctive to
her, at least, though for reasons still ob
scure, undetectable by others.
Mrs Milne first noticed this odour when
her husband developed the illness. She
made the general connection later, when
she smelled it at sufferers’ support groups
attended by her spouse. Tests using clothes
worn by patients confirmed her ability. She
even noted one seemingly healthy individ
ual as having the disease months before
other symptoms developed.
Carting Mrs Milne around the world to
sniff patients who may have Parkinson’s is,
however, not a practical option, so re
searchers working with her looked for the
odour’s source, with a view to detecting it
in some other way. They found it in sebum,
an oily secretion produced by the skin. The
sebum of those with Parkinson’s, they dis
covered, has unusually high concentra
tions of certain volatile organic com
pounds, including dodecane, acetone and
ethyl acetate. When these are acted on by
yeast cells which live naturally on the skin,
the result is the mysterious odour.This Parkinson’sspecific list can be de
tected using a laboratory technique called
gas chromatographymass spectrometry
(gcms), which is promising—for gcmsma
chines are a bit more deployable than Mrs
Milne is. Unfortunately, they are still too
complex and expensive to be used routine
ly in clinics. However, Dr Chen and Dr Liu,
who are both biomedical engineers, reck
oned they could come up with a cheaper
and more portable alternative.
The upshot is a machine not much big
ger than a toaster. It turns a sample of se
bum into a vapour that is then probed with
sound waves. Different molecular mix
tures have different effects on the waves,
and, with a bit of training, a computer
loaded with an appropriate piece of artificial intelligence can learn to recognise the
pattern associated with sebum from Par
kinson’s patients.
The researchers tested their system on
samples from 43 people with Parkinson’s
disease and 44 who were healthy. They
found it could correctly identify a Parkin
son’s patient as having the disease about
70% of the time and a healthy control as
being clear of it about 80%. That is not yet
as good as Mrs Milne’s nose, which has a
history of correctly identifying the pres
ence of Parkinson’s all the time. But it is a
start. If its reliability can be improved, the
compactness and potential cheapness of
the system Dr Chen and Dr Liuhavecome
up with may eventually provea boon for
the early diagnosis of the illness.nAn artificial sniffer may be able to
detect Parkinson’s disease earlyT
hisisthesternofEndurance, oneof
the 20th century’s most famous
ships. She was lost in 1915, in the Weddell
Sea, an icebound part of the Southern
Ocean off the coast of Antarctica.
Her captain was Frank Worsley. But
the leader of the expedition she was
carrying was Ernest Shackleton, a British
explorer who, having been beaten to the
South Pole by Roald Amundsen’s journey
there and back in 1911, planned instead to
lead his party across Antarctica from one
side to the other.
That ambition ended when Endurance
got stuck in the ice, and was then
crushed by it. She sank, but slowly
enough for the expedition’s supplies to
be recovered. Shackleton then led the 27
other men in the party on a perilous trip
using Endurance’s boats, which took
them ultimately to safety at the whaling
station of Grytviken, on South Georgia,
about 1,300km from the place where thevesselhadfoundered.
The discovery of the wreck, which lay
at a depth of 1,645 fathoms (3,008 me
tres), was announced on March 9th by
the Falklands Maritime Heritage Trust,
which had organised a search of the
seabed in the area whereEndurancesank,
using uncrewed underwater search
vehicles called Sabertooths. She was 6km
from her last position on the surface, as
recorded by Worsley.
Though some doubt the story’s verac
ity, Shackleton is said to have recruited
his compadres by placing in a newspaper
an advert that read, “Men wanted for
hazardous journey. Small wages, bitter
cold, long months of complete darkness,
constant danger, safe return doubtful.
Honour and recognition in case of suc
cess”. It being early 20thcentury Britain,
though, honour and recognition were
also available for heroic failure. And few
failures were more heroic than this one.UnderwaterarchaeologyPatience and Endurance
After more than a century, a famous shipwreck has been located