Name four creatures beginning with the letter "S". What is 4 plus 15 minus 17? Why is a carrot like a potato?
If these questions cause you trouble, don't worry - chances are you're just having an off day. Certainly no one in the prime of life should lose sleep over the fact that they're part of a new test for Alzheimer's disease, the most common form of dementia.
But what if you're not as young as you once were? With some media organisations putting the entire test online and claiming it is 93 per cent accurate, it is tempting to try it out or give it to an elderly relative you are concerned about.
Yet these reports should carry a big health warning: don't try this at home. The test may be quick and simple, but it is also potentially highly misleading. That is not because the researchers behind the test have exaggerated its reliability: the problem lies in a phenomenon which often wrong-foots even experts.
At its heart is a mathematical result called Bayes's Theorem, which shows how to update our beliefs in the light of new evidence. While the formula itself is somewhat involved, its implications are straightforward: be wary of vague talk about "accuracy".
In the case of the new test for Alzheimer's, the media reports make much of an "accuracy rate" of 93 per cent. But what, exactly, does that mean? Reporting the research behind their new test in the current issue of the British Medical Journal, the neurologist Jeremy Brown and his colleagues at Addenbrooke's Hospital, Cambridge, UK, are clear: the 93 per cent is the percentage of patients correctly identified by the test as having Alzheimer's disease - or, in the jargon, the "true positive" rate
But Bayes's Theorem shows this figure alone does not capture the reliability of the test: after all, it might be effective at detecting the disease, but only at the expense of falsely detecting Alzheimer's in many healthy patients. We therefore also need the "false positive" rate - that is, how often it leads to the wrong diagnosis.
Again, Dr Brown and his colleagues have this covered, and state that their test wrongly diagnosed Alzheimer's in 14 per cent of healthy patients. Ignored in media reports, this figure is vital in gauging the test's effectiveness. Bayes's Theorem does this via the so-called "Likelihood Ratio" (LR) - the true positive rate divided by the false positive rate, which for the Addenbrooke's test is 93/14, or around 7. Thus whatever the original level of belief about a patient having Alzheimer's, a positive result from the test means that belief should increase seven-fold. Levels of belief can be captured via the odds we would give on their proving correct. So, for example, if we initially thought there was a one per cent chance of a patient having Alzheimer's, a positive result from the test would increase those chances to around seven per cent.
That's far short of the 93 per cent chance implied by that "accuracy" figure quoted in the media. But as Bayes's Theorem shows, that is because the prior probability that the person had Alzheimer's was already very low, and not even the seven-fold increase in weight of evidence supplied by the new test can boost that to a high probability.
And that is pretty crucial for anyone under the age of 80 who takes the test. While Alzheimer's disease becomes more prevalent with age, even septuagenarians face only around a 1 in 20 chance of developing it. Bayes's Theorem then shows that even the "93 per cent accurate" Addenbrooke's test is more likely to be wrong than right among septuagenarians - because of the low prevalence of Alzheimer's within their age group.
The rule of thumb is this: a positive result from any test is most likely to be wrong if its false positive rate exceeds the prevalence of whatever is being detected.
Does this mean the Addenbrooke's test is useless? Not at all. With its false positive rate of 14 per cent, the rule of thumb means a positive result is likely to be correct for anyone over the age of 80 - as the prevalence of Alzheimer's in this age group exceeds 20 per cent. Even among younger age groups, the test will be helpful in screening prior to further tests. This is how Dr Brown and his colleagues want to see it used - and in this they are backed by Bayes's Theorem, which shows that further tests rapidly boost the weight of evidence.
It may come as little surprise that the Addenbrooke's team has a better grasp of Bayes's Theorem than the media - but perhaps it should. Research by Professor Gerd Gigerenzer and his colleagues at the Max Planck Institute, Berlin, has shown that many medics struggle with its implications.
In one study, a group of doctors was asked to estimate the chances that a patient really does have breast cancer - affecting one per cent of women - given a positive result from a test with a true positive rate of 80 per cent, and a false alarm rate of 10 per cent.
Most of the doctors put the chances as at least 70 per cent. Yet just knowing the rule of thumb shows this can't be right. With a false alarm rate 10 times greater than the prevalence of the disease, the positive result is far more likely to be wrong than right. The correct answer, found by just two doctors - who presumably knew something about Bayes - is 8 per cent.
With home diagnostic kits for everything from allergies to cancer now coming on the market, doctors should brace themselves for increasing numbers of distraught but perfectly healthy patients - and mug up the basics of Bayes.
Robert Matthews is a Visiting Reader in Science at Aston University, Birmingham, England
The rules on fostering in the UAE
A foster couple or family must:
- be Muslim, Emirati and be residing in the UAE
- not be younger than 25 years old
- not have been convicted of offences or crimes involving moral turpitude
- be free of infectious diseases or psychological and mental disorders
- have the ability to support its members and the foster child financially
- undertake to treat and raise the child in a proper manner and take care of his or her health and well-being
- A single, divorced or widowed Muslim Emirati female, residing in the UAE may apply to foster a child if she is at least 30 years old and able to support the child financially
Formula Middle East Calendar (Formula Regional and Formula 4)
Round 1: January 17-19, Yas Marina Circuit – Abu Dhabi
Round 2: January 22-23, Yas Marina Circuit – Abu Dhabi
Round 3: February 7-9, Dubai Autodrome – Dubai
Round 4: February 14-16, Yas Marina Circuit – Abu Dhabi
Round 5: February 25-27, Jeddah Corniche Circuit – Saudi Arabia
Essentials
The flights
Emirates and Etihad fly direct from the UAE to Los Angeles, from Dh4,975 return, including taxes. The flight time is 16 hours. Alaska Airlines, United Airlines, Delta Air Lines, Aeromexico and Southwest all fly direct from Los Angeles to San Jose del Cabo from Dh1,243 return, including taxes. The flight time is two-and-a-half hours.
The trip
Lindblad Expeditions National Geographic’s eight-day Whales Wilderness itinerary costs from US$6,190 (Dh22,736) per person, twin share, including meals, accommodation and excursions, with departures in March and April 2018.
UAE cricketers abroad
Sid Jhurani is not the first cricketer from the UAE to go to the UK to try his luck.
Rameez Shahzad Played alongside Ben Stokes and Liam Plunkett in Durham while he was studying there. He also played club cricket as an overseas professional, but his time in the UK stunted his UAE career. The batsman went a decade without playing for the national team.
Yodhin Punja The seam bowler was named in the UAE’s extended World Cup squad in 2015 despite being just 15 at the time. He made his senior UAE debut aged 16, and subsequently took up a scholarship at Claremont High School in the south of England.
THREE
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Voices: How A Great Singer Can Change Your Life
Nick Coleman
Jonathan Cape
In numbers: PKK’s money network in Europe
Germany: PKK collectors typically bring in $18 million in cash a year – amount has trebled since 2010
Revolutionary tax: Investigators say about $2 million a year raised from ‘tax collection’ around Marseille
Extortion: Gunman convicted in 2023 of demanding $10,000 from Kurdish businessman in Stockholm
Drug trade: PKK income claimed by Turkish anti-drugs force in 2024 to be as high as $500 million a year
Denmark: PKK one of two terrorist groups along with Iranian separatists ASMLA to raise “two-digit million amounts”
Contributions: Hundreds of euros expected from typical Kurdish families and thousands from business owners
TV channel: Kurdish Roj TV accounts frozen and went bankrupt after Denmark fined it more than $1 million over PKK links in 2013
The smuggler
Eldarir had arrived at JFK in January 2020 with three suitcases, containing goods he valued at $300, when he was directed to a search area.
Officers found 41 gold artefacts among the bags, including amulets from a funerary set which prepared the deceased for the afterlife.
Also found was a cartouche of a Ptolemaic king on a relief that was originally part of a royal building or temple.
The largest single group of items found in Eldarir’s cases were 400 shabtis, or figurines.
Khouli conviction
Khouli smuggled items into the US by making false declarations to customs about the country of origin and value of the items.
According to Immigration and Customs Enforcement, he provided “false provenances which stated that [two] Egyptian antiquities were part of a collection assembled by Khouli's father in Israel in the 1960s” when in fact “Khouli acquired the Egyptian antiquities from other dealers”.
He was sentenced to one year of probation, six months of home confinement and 200 hours of community service in 2012 after admitting buying and smuggling Egyptian antiquities, including coffins, funerary boats and limestone figures.
For sale
A number of other items said to come from the collection of Ezeldeen Taha Eldarir are currently or recently for sale.
Their provenance is described in near identical terms as the British Museum shabti: bought from Salahaddin Sirmali, "authenticated and appraised" by Hossen Rashed, then imported to the US in 1948.
- An Egyptian Mummy mask dating from 700BC-30BC, is on offer for £11,807 ($15,275) online by a seller in Mexico
- A coffin lid dating back to 664BC-332BC was offered for sale by a Colorado-based art dealer, with a starting price of $65,000
- A shabti that was on sale through a Chicago-based coin dealer, dating from 1567BC-1085BC, is up for $1,950
SPEC%20SHEET%3A%20SAMSUNG%20GALAXY%20S23%20ULTRA
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What are the GCSE grade equivalents?
- Grade 9 = above an A*
- Grade 8 = between grades A* and A
- Grade 7 = grade A
- Grade 6 = just above a grade B
- Grade 5 = between grades B and C
- Grade 4 = grade C
- Grade 3 = between grades D and E
- Grade 2 = between grades E and F
- Grade 1 = between grades F and G
Key facilities
- Olympic-size swimming pool with a split bulkhead for multi-use configurations, including water polo and 50m/25m training lanes
- Premier League-standard football pitch
- 400m Olympic running track
- NBA-spec basketball court with auditorium
- 600-seat auditorium
- Spaces for historical and cultural exploration
- An elevated football field that doubles as a helipad
- Specialist robotics and science laboratories
- AR and VR-enabled learning centres
- Disruption Lab and Research Centre for developing entrepreneurial skills
North Pole stats
Distance covered: 160km
Temperature: -40°C
Weight of equipment: 45kg
Altitude (metres above sea level): 0
Terrain: Ice rock
South Pole stats
Distance covered: 130km
Temperature: -50°C
Weight of equipment: 50kg
Altitude (metres above sea level): 3,300
Terrain: Flat ice
Test
Director: S Sashikanth
Cast: Nayanthara, Siddharth, Meera Jasmine, R Madhavan
Star rating: 2/5
The specs
Engine: 4.0-litre flat-six
Torque: 450Nm at 6,100rpm
Transmission: 7-speed PDK auto or 6-speed manual
Fuel economy, combined: 13.8L/100km
On sale: Available to order now
Specs
Engine: 51.5kW electric motor
Range: 400km
Power: 134bhp
Torque: 175Nm
Price: From Dh98,800
Available: Now
UAE - India ties
The UAE is India’s third-largest trade partner after the US and China
Annual bilateral trade between India and the UAE has crossed US$ 60 billion
The UAE is the fourth-largest exporter of crude oil for India
Indians comprise the largest community with 3.3 million residents in the UAE
Indian Prime Minister Narendra Modi first visited the UAE in August 2015
His visit on August 23-24 will be the third in four years
Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the Armed Forces, visited India in February 2016
Sheikh Mohamed was the chief guest at India’s Republic Day celebrations in January 2017
Modi will visit Bahrain on August 24-25
Mercer, the investment consulting arm of US services company Marsh & McLennan, expects its wealth division to at least double its assets under management (AUM) in the Middle East as wealth in the region continues to grow despite economic headwinds, a company official said.
Mercer Wealth, which globally has $160 billion in AUM, plans to boost its AUM in the region to $2-$3bn in the next 2-3 years from the present $1bn, said Yasir AbuShaban, a Dubai-based principal with Mercer Wealth.
“Within the next two to three years, we are looking at reaching $2 to $3 billion as a conservative estimate and we do see an opportunity to do so,” said Mr AbuShaban.
Mercer does not directly make investments, but allocates clients’ money they have discretion to, to professional asset managers. They also provide advice to clients.
“We have buying power. We can negotiate on their (client’s) behalf with asset managers to provide them lower fees than they otherwise would have to get on their own,” he added.
Mercer Wealth’s clients include sovereign wealth funds, family offices, and insurance companies among others.
From its office in Dubai, Mercer also looks after Africa, India and Turkey, where they also see opportunity for growth.
Wealth creation in Middle East and Africa (MEA) grew 8.5 per cent to $8.1 trillion last year from $7.5tn in 2015, higher than last year’s global average of 6 per cent and the second-highest growth in a region after Asia-Pacific which grew 9.9 per cent, according to consultancy Boston Consulting Group (BCG). In the region, where wealth grew just 1.9 per cent in 2015 compared with 2014, a pickup in oil prices has helped in wealth generation.
BCG is forecasting MEA wealth will rise to $12tn by 2021, growing at an annual average of 8 per cent.
Drivers of wealth generation in the region will be split evenly between new wealth creation and growth of performance of existing assets, according to BCG.
Another general trend in the region is clients’ looking for a comprehensive approach to investing, according to Mr AbuShaban.
“Institutional investors or some of the families are seeing a slowdown in the available capital they have to invest and in that sense they are looking at optimizing the way they manage their portfolios and making sure they are not investing haphazardly and different parts of their investment are working together,” said Mr AbuShaban.
Some clients also have a higher appetite for risk, given the low interest-rate environment that does not provide enough yield for some institutional investors. These clients are keen to invest in illiquid assets, such as private equity and infrastructure.
“What we have seen is a desire for higher returns in what has been a low-return environment specifically in various fixed income or bonds,” he said.
“In this environment, we have seen a de facto increase in the risk that clients are taking in things like illiquid investments, private equity investments, infrastructure and private debt, those kind of investments were higher illiquidity results in incrementally higher returns.”
The Abu Dhabi Investment Authority, one of the largest sovereign wealth funds, said in its 2016 report that has gradually increased its exposure in direct private equity and private credit transactions, mainly in Asian markets and especially in China and India. The authority’s private equity department focused on structured equities owing to “their defensive characteristics.”