TIME psychology

How Not To Assess Risk

Roman poet and philosopher Titus Lucretius Carus (circa 95 - 55 BC).
Spencer Arnold—Getty Images Roman poet and philosopher Titus Lucretius Carus (circa 95 - 55 BC).

Shane Parrish writes Farnam Street

It’s always good to re-read books and to dip back into them periodically. When reading a new book, I often miss out on crucial information (especially books that are hard to categorize with one descriptive sentence). When you come back to a book after reading hundreds of others you can’t help but make new connections with the old book and see it anew.

It has been a while since I read Anti-fragile. In the past I’ve talked about an Antifragile Way of Life, Learning to Love Volatility, the Definition of Antifragility , Antifragile life of economy, and the Noise and the Signal.

But upon re-reading Antifragile I came across the Lucretius Problem and I thought I’d share an excerpt. (Titus Lucretius Carus was a Roman poet and philosopher, best-known for his poem On the Nature of Things). Taleb writes:

Indeed, our bodies discover probabilities in a very sophisticated manner and assess risks much better than our intellects do. To take one example, risk management professionals look in the past for information on the so-called ​worst-case scenario ​and use it to estimate future risks – this method is called “stress testing.” They take the worst historical recession, the worst war, the worst historical move in interest rates, or the worst point in unemployment as an exact estimate for the worst future outcome​. But they never notice the following inconsistency: this so-called worst-case event, when it happened, exceeded the worst [known] case at the time.

I have called this mental defect the Lucretius problem, after the Latin poetic philosopher who wrote that the fool believes that the tallest mountain in the world will be equal to the tallest one he has observed. We consider the biggest object of any kind that we have seen in our lives or hear about as the largest item that can possibly exist. And we have been doing this for millennia.

Taleb brings up an interesting point, which is that our documented history can blind us. All we know is what we have been able to record.

We think because we have sophisticated data collecting techniques that we can capture all the data necessary to make decisions. We think we can use our current statistical techniques to draw historical trends using historical data without acknowledging the fact that past data recorders had fewer tools to capture the dark figure of unreported data. We also overestimate the validity of what has been recorded before and thus the trends we draw might tell a different story if we had the dark figure of unreported data.

Taleb continues:

The same can be seen in the Fukushima nuclear reactor, which experienced a catastrophic failure in 2011 when a tsunami struck. It had been built to withstand the worst past historical earthquake, with the builders not imagining much worse— and not thinking that the worst past event had to be a surprise, as it had no precedent. Likewise, the former chairman of the Federal Reserve, Fragilista Doctor Alan Greenspan, in his apology to Congress offered the classic “It never happened before.” Well, nature, unlike Fragilista Greenspan, prepares for what has not happened before, assuming worse harm is possible.

So what do we do and how do we deal with the blindness?

Taleb provides an answer which is to develop layers of redundancy to act as a buffer against oneself. We overvalue what we have recorded and assume it tells us the worst and best possible outcomes. Redundant layers are a buffer against our tendency to think what has been recorded is a map of the whole terrain. An example of a redundant feature could be a rainy day fund which acts as an insurance policy against something catastrophic such as a job loss that allows you to survive and fight another day.

Antifragile is a great book to read and you might learn something about yourself and the world you live in by reading it or in my case re-reading it.

This piece originally appeared on Farnam Street.

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TIME Books

39 Books to Help You Make Decisions in Life

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Shane Parrish writes Farnam Street

At Re:Think Decision Making in February, I asked participants to offer up some books on decision making. (If you’d like to be one of the first to know when I open up registration for Re:Think Decision making 2016 in Austin, TX , join the list.)

The crowd at the event was, in the words of one participants, the finest crowd you’ll find at a public event. These people are paid to make decisions for a living and want to find every edge they can. So when I asked them what books on decision making they read and recommend, you can bet they had a lot to say.

Here’s the list:

Decisive: How to Make Better Choices in Life and Work
By: Chip & Dan Heath

How to Measure Anything
By: Douglas Hubbard

How to Make Sense of Any Mess: Information Architecture for Everybody
By: Abby Covert

Wiser: Getting Beyond Groupthink to Make Groups Smarter
By: Cass Sunstein & Reid Hastie

The Surprising Power of Liberating Structures: Simple Rules to Unleash A Culture of Innovation
By: Henri Lipmanowicz & Keith McCandless

Gamestorming: A Playbook for Innovators, Rulebreakers, and Changemakers
By: Dave Gray, Sunni Brown & James Macanufo

The Righteous Mind: Why Good People are Divided by Politics and Religion
By: Jonathan Haidt

Yes or No: The Guide to Better Decisions
By: Spencer Johnson

The Little Book of Talent
By: Daniel Coyle

The Worry Solution: Using Breakthrough Brain Science to Turn Stress and Anxiety into Confidence and Happiness
By: Martin Rossman

Shantaram: A Novel
By: Gregory David Roberts

The Art of Living
By: Epictetus

The Education of a Value Investor
By: Guy Spier

Devil Take the Hindmost: a History of Financial Speculation
By: Edward Chancellor

Click: The Art and Science of Getting from Impasse to Insight
By: Eve Grodnitzky

The Dictator’s Handbook: Why Bad Behavior is Almost Always Good Politics
By: Bruce Bueno de Mesquita

The Back of the Napkin & How to Solve Problems and Sell Ideas
By: Dan Roan

Crossing to Safety
By: Wallace Stegner

Paradox of Choice: Why More is Less
By: Barry Schwartz

Streetlights and Shadows: Searching for the Keys to Adaptive Decision Making
By: Gary Klein

The Social Animal
By: David Brooks

The Laws of Simplicity
By: John Maeda

Nudge: Improving Decisions about Health, Wealth and Happiness
By: Richard H. Thaler

Reminiscences of a Stock Operator
By: Edwin Lefevre & Roger Lowenstein

This Will Make You Smarter
By: John Brockman

A more Beautiful Question: The Power of Inquiry to Spark Breakthrough Ideas
By: Warren Berger

Red Notice: A True Story of High Finance, Murder, and One Man’s Fight for Justice
By: Bill Browden

The Man who Mistook his Wife for a Hat
By: Oliver Sacks

Imprudent King: A New Life of Philip II
By: Geoffrey Parker

Seeking Wisdom
By: Peter Bevelin

By: Rober Greene

Synchronicity: The Innes Path of Leadership
By: Joseph Jaworski

The Culture Map: Breaking Through the Invisible Boundaries of Global Business
By: Erin Meyer

Ubiquity: Why Catastrophes Happen
By: Mark Buchanan

Family Fortunes
By: Bill Bonner

Influence: The Psychology of Persuasion
By: Robert Cialdini

Antifragile: Things That Gain from Disorder
By: Nassim Nicholas Taleb

Poor Charlie’s Almanack: The Wit and Wisdom of Charles T. Munger
By: Peter D. Kaufman & Charlie T. Munger

The Brain that Changes Itself
By: Norman Doidge

And there you have it — a list of books on decision making that should give you a great starting point.

This piece originally appeared on Farnam Street.

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TIME psychology

The Trick to Memorizing an Entire Foreign Dictionary

Practice makes perfect

New Zealand’s Nigel Richards, who doesn’t speak French, has won the French-language Scrabble world championships. In the Scrabble world, Richards is considered to be the best player ever, having won the English world Scrabble championships three times, the U.S. national championships five times and the U.K. Open six times. His latest remarkable feat was achieved after reportedly memorising the entire French Scrabble dictionary in just nine weeks.

Richards is not the only person who has wowed the world with exceptional memory skills. Dave Farrow is the Guinness World Record holder for greatest memory. In 2007 he spent around 14 hours memorising a random sequence of 59 separate packs of cards (3,068 individual cards), looking at each card once. In 1981, Rajan Mahadevan recited from memory the first 31,811 digits of pi, a record that was astonishingly broken by Hideaki Tomoyori in 1987, who recited 40,000 digits.

For those of us struggling to remember what happened a couple of days ago, such innately superior memory capacity is remarkable. The question of whether these people are born with exceptional memory ability or acquire it by deliberate practice has interested both scientists and the general public alike for hundreds of years.

Memory genius comes with practice

Many books were published in the 1980s and 90s on the topic of genius and exceptional performance, with pioneering research comparing the superior performance of chess experts over beginners.

What became apparent, however, is that, although some people were able to recall large amounts of information seemingly effortlessly, their memory was truly exceptional only for materials that were specific to their expertise. In one study in the 1970s, William Chase and Herbert Simon at Carnegie Mellon University had world chess experts recall the configuration of chess pieces on a chessboard. When the chess experts were shown an actual chess positioned board, their recall of the pieces was far superior to novices. However, with random chessboards, players of all skill level had the same poor recall performance.

In order to answer the question of how to achieve exceptional memory performance, Chase, alongside K Anders Ericsson, developed the “skilled memory theory” which proposed three basic principles.

First, individuals need to rely on prior knowledge and patterns to encode and store the material in long-term-memory – what they called the “encoding principle.” Second, encoded information needs a “retrieval structure” – meaning it is associated with a cue when first seen so that it can be triggered during retrieval from long-term memory. And third, with additional practice people become more proficient in their encoding and can store the same amount of presented information in less time – the “speed-up principle.”

Techniques to try

What this is referring to is a mnemonic strategy. We are all capable of using such strategies although some of us are more skilled at it then others. The oldest and most common method is the method of loci (Latin for “places”). In the method of loci, the mnemonist first creates a series of places, imagined rooms (the encoding principle), then puts what is to be remembered in said rooms, and finally walks from room to room in a fixed order, to recall the material (retrieval structure principle).

The more familiar and elaborate the detail of the imagined place is, the faster they will be able to place and retrieval material (the speed-up principle). Many mnemonic methods such as loci require such visualisation. For example, digit sequences can be associated with word links. If 59 is “lip” and 47 is “rock”, then 5947 can be remembered by an interactive image of “lips kissing a rock.” Other mnemonic techniques include a digit-consonant system or converting digits into syllables (based on the Japanese language) which are then regrouped into words.

Although Richards is a somewhat reclusive figure, so we can’t say for certain what techniques he used, it is more than likely that he is highly skilled at mnemonic strategies, along with having an exceptional mathematical talent to play scrabble. He, and others like him are able to utilize mnemonic strategies beyond our comprehensible understanding. However, whether it is his dedication to practice or some innate superior memory that is responsible for this ability is still under scientific investigation.

This article originally appeared on The ConversationThe Conversation

TIME Ideas hosts the world's leading voices, providing commentary and expertise on the most compelling events in news, society, and culture. We welcome outside contributions. To submit a piece, email ideas@time.com.

TIME psychology

How to Avoid Getting Tricked By the Past

Shane Parrish writes Farnam Street

The fact that new information exists about the past in general means that we have an incomplete road map about history. There is a necessarily fallibility … if you will.

In The Black Sawn, Nassim Taleb writes:

History is useful for the thrill of knowing the past, and for the narrative (indeed), provided it remains a harmless narrative. One should learn under severe caution. History is certainly not a place to theorize or derive general knowledge, nor is it meant to help in the future, without some caution. We can get negative confirmation from history, which is invaluable, but we get plenty of illusions of knowledge along with it.

While I don’t entirely hold Taleb’s view, I think it’s worth reflecting on. As a friend put it to me recently, “when people are looking into the rear view mirror of the past, they can take facts and like a string of pearls draw lines of causal relationships that facilitate their argument while ignoring disconfirming facts that detract from their central argument or point of view.”

Taleb advises us to adopt the empirical skeptic approach of Menodotus which was to “know history without theorizing from it,” and to not draw any large theoretical or scientific claims.

We can learn from history but our desire for causality can easily lead us down a dangerous rabbit hole when new facts come to light disavowing what we held to be true. In trying to reduce the cognitive dissonance, our confirmation bias leads us to reinterpret past events in a way that fits our current beliefs.

History is not stagnant — we only know what we know currently and what we do know is subject to change. The accepted beliefs about how events played out may change in light of new information and then the new accepted beliefs may change over time as well.

This piece originally appeared on Farnam Street.

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TIME Exercise/Fitness

How Exercise Helps Curb Alzheimer’s Symptoms

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Most studies so far have focused on the importance of physical activity before you develop Alzheimer’s. But can it treat the disease once you are diagnosed? Two studies hint that may be the case

At the annual Alzheimer’s Association International Conference in July 2015, scientists report some encouraging news about the benefits of exercise. In the first studies to look at physical activity among people already diagnosed with the early stages of Alzheimer’s, moderate to high intensity workouts may not only slow down the biological symptoms of Alzheimer’s—but may lead to improvements in cognitive functions as well.

In one study involving 200 people with mild or moderate disease, Dr. Steen Hasselbalch from the University of Copenhagen and his colleagues randomly assigned some participants to an hour of exercise three times a week for 16 weeks, while allowing the remainder to continue without a regular activity regimen. After a phase-in period, the exercisers were working at a moderate to intense level, achieving 70% to 80% of their maximum heart rate for at least half of each session.

MORE: Your School Grades Affect Your Risk of Dementia

That level of intensity is important, says Hasselbalch, to achieve results. Compared to the control group, the exercisers showed fewer symptoms such as anxiety, changes in mood and depression that are common among Alzheimer’s patients. Overall, those who were more active did not show any changes in cognitive functions, but when Hasselbalch looked at the results more carefully, he found that participants with milder disease who exercised actually did perform better on intellectual skills after the 16 weeks. They were tested on memory, language, mental speed and other executive functions.

“It’s been shown with other diseases that exercise can have beneficial effects,” he says. “Now we have shown it’s also important for dementia. So if you now have this alternative treatment, it sends a message that you can do something even after diagnosis to treat dementia.”

MORE: Two New Alzheimer’s Drugs Offer Hope—With Caveats

Because the people exercised in a group setting, he says that simply being part of that social situation and getting out of the house and interacting with others appears to reduce the mood-related symptoms of Alzheimer’s. “But if you really want an effect on cognition, then you have to exercise hard.”

He admits that his study did not delve into how the exercise might be contributing to the improved cognitive changes, but he will be analyzing the blood and cerebral spinal fluid collected from the participants to study that further.

MORE: Alzheimer’s May Show Up in Saliva

Such changes are what Laura Baker, from Wake Forest School of Medicine, and her team did with another group of early stage Alzheimer’s patients. They wanted to see what biological changes exercise might have on the Alzheimer’s process, and focused on 70 patients with mild cognitive impairment and diabetes, both of which significantly increase the risk for Alzheimer’s. Some were randomly assigned to simple stretching exercises, while others were told to exercise four times a week and, like those in Hasselbalch’s study, had to work hard enough to raise their heart rate to 70% to 80% of its maximum for 30 of the 45 minutes of each session. Baker then studied their cognitive function tests, brain imaging and levels of Alzheimer’s proteins in their cerebral spinal fluid.

She found that those who exercise rigorously increased the blood flow in the areas of the brain responsible for memory and higher level processing. The result was a dramatically increased score, by 80%, on average on the cognitive tests than those who just stretched, even after accounting for age-related changes in thinking. More intriguing, the exercisers also showed on average a 14% lower level of the protein tau, which is a good indicator that brain neurons are dying and Alzheimer’s processes are well underway, at the end of the study compared to before they began the exercise regimen.

“What’s encouraging to us is that we don’t have treatments now; there’s nothing for Alzheimer’s patients,” says Baker. “The possibility that a non-medicine intervention could actually change the disease — we’re just very encouraged by these results,.”

While the exercise regimen wasn’t an easy one — it qualifies as moderately intense physical activity, which for a group of older adults who are likely sedentary to begin with is certainly a challenge, both Hasselbalch and Baker say that with the right execution — by working with participants and by gradually increasing their exercise level — achieving the amounts of activity needed to help their brains is possible. Baker also points out that it’s time to start studying the combined effects of new medications that are being tested for Alzheimer’s and increased physical activity. Together, she says, they may hold the key to actually slowing down and possibly even reversing progression of the disease.

TIME Innovation

How Damaged Brains Can Learn From Healthy Ones

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

These are today's best ideas

1. Could damaged brains learn to heal from healthy ones?

By Brian Handwerk at Smithsonian Magazine

2. From VOA to Radio Free Europe, the U.S. needs a single news voice abroad.

By Al Pessin at Defense One

3. Here’s how the dwindling teacher supply is complicating education reform.

By Paul Bruno in the Brown Center Chalkboard at the Brookings Institution

4. The mobile web sucks.

By Nilay Patel in the Verge

5. What’s better than a clinical trial for understanding drug side effects?

By Aviva Rutkin in New Scientist

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

TIME Ideas hosts the world's leading voices, providing commentary and expertise on the most compelling events in news, society, and culture. We welcome outside contributions. To submit a piece, email ideas@time.com.

TIME Brain

Two New Alzheimer’s Drugs Offer Hope—With Caveats

Missing jigsaw piece in head
Getty Images

Reports on two compounds provide limited optimism in the search for pharmaceutical answers to treating Alzheimer’s disease

Reporting at the Alzheimer’s Association International Conference in Washington, D.C., researchers showed some glimmers of hope in the potential benefit of two agents being tested in patients with mild to moderate Alzheimer’s disease. Currently, there are no treatments that address the root causes of the neurodegenerative condition, which include the build up of amyloid plaques in the brain and the formation of tau tangles once nerve cells start to die off.

One drug, from Eli Lilly, aims to soak up amyloid and thus prevent it from accumulating in the damaging plaques that suffocate neurons in the brain. But to test its effectiveness in a timely manner, the scientists adopted an unorthodox trial design — they divided participants with mild to moderate disease into two groups, one that took the drug, which is given via IV, and another that took placebo. After 18 months, there were no significant differences between the groups on cognitive tests, although people with mild disease seemed to show signs of improvement. So those on placebo were then switched to the study drug, called solanezumab, and followed for another 18 months to two years. The idea was that by the end of the study, the participants who had been taking the drug all along should show greater improvements in cognitive skills than those who switched midway through.

MORE: Alzheimer’s May Show Up in Saliva

That’s what the researchers saw. In their report, they said that the two groups showed differences in their thinking abilities. But whether that gap can be attributed to the drug alone isn’t entirely clear—at least not yet. And whether that difference is enough to fuel further study, especially in people at the earliest stages of the disease, or form the basis of an approval by the Food and Drug Administration is even more uncertain.

MORE: Your School Grades Affect Your Risk of Dementia

The other experimental agent, aducanumab, also sops up amyloid, but was associated with brain swelling in earlier studies at higher doses. Scientists at Biogen, which is developing the compound, added an intermediate dose to get a better sense of how much of the drug could produce the most benefit without triggering side effects. The results were from an earlier stage of testing, and focused primarily on safety of these doses so developers could not say for certain whether the improvements they began to see in slowing cognitive decline were significant. But they were enough to warrant more study.

Both trials show that, while promising, the first-ever treatments for Alzheimer’s have a ways to go still on this long, and often precarious road.

TIME Research

Alzheimer’s May Show Up in Saliva

Identifying Alzheimer’s well before symptoms appear may become easier with a saliva test

The latest advances in Alzheimer’s disease involve people who don’t appear to show any signs of cognitive decline yet. Experts now believe that the biological processes behind the neurodegenerative condition begin years, if not decades, before memory problems and confusion become noticeable.

At the annual Alzheimer’s Association International Conference, researchers say they have found a series of substances in saliva that can distinguish between people who experience normal aging, those with mild cognitive dementia (MCI, which in some cases can lead to Alzheimer’s and in other cases not), and Alzheimer’s disease.

Presenting at the meeting, Shraddha Sapkota, a graduate student in neuroscience at University of Alberta, and her colleagues described how they carefully analyzed the saliva of a group of volunteers participating in an aging study. Some had been diagnosed with Alzheimer’s and some with MCI, while others did not have any neurological conditions. By comparing their saliva components, the scientists found that each of the three groups showed slightly different patterns of compounds, which could form the basis of a relatively easy and non-invasive way to determine which people are at higher risk of developing more serious degenerative brain conditions.

The results aren’t conclusive enough yet for doctors to start using them to distinguish people who are more likely to develop Alzheimer’s, but that’s the goal, says Sapkota. Ideally, for example, isolating those with MCI might help doctors to focus in on a group of patients who might be at higher risk of developing Alzheimer’s and therefore might need more intensive and regular testing.

TIME Research

Your School Grades Affect Your Risk of Dementia

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Building up a dementia-resistant brain and protecting against Alzheimer’s begins a early as childhood, the latest research suggests

In a presentation at the Alzheimer’s Association International Conference, scientists report that getting good grades in school is among the important factors that can protect against dementia later in life.

Experts have known that people with so-called cognitive reserve, or the ability to compensate for the failing parts of the brain in degenerative conditions such as Alzheimer’s, can help to slow down or stave off some symptoms of memory loss, confusion and disorientation. But it wasn’t clear when the buildup of these reserves should begin.

MORE: New Research on Understanding Alzheimer’s

In a study involving 7,574 people who were at least 65 years old and followed for 21 years, Serhiy Dekhtyar, a postdoctoral research fellow at the Karolinska Institute, and his colleagues found that the chance of developing dementia was strongly linked to how well the people in the study did in school during childhood. Those with grades in the lowest 20% showed the highest risk of developing dementia later on, an effect that remained strong even if the volunteers went on to attain more education and had intellectually demanding jobs. In other words, says Dekhtyar, “Your early life baseline cognitive abilities play a role in later dementia risk, which we didn’t know before because we didn’t have data. Now we have the data that show there is a component of early cognitive abilities that seems to still [have an effect] 50 or 60 years later.”

Most studies focus on people who already have dementia and look at the effect that intellectual engagement in later life can have in slowing the progression of dementia or reducing some of its symptoms. The idea is that the more intellectual activities the brain has, the stronger and more robust its network of neurons. Someone with larger cognitive reserves, therefore, can function with fewer symptoms than someone with lesser reserves, even if both have the same amount of damage caused by degenerative diseases like Alzheimer’s.

MORE: Mental and Social Activity Delays the Symptoms of Alzheimer’s

Those with the most protection in the study were people who had good grades during childhood and who ended up in demanding jobs; they lowered their risk of dementia by about 40%. While having a complex intellectual job lowered risk of dementia by 23%, it couldn’t completely negate the effects of not being a good student in school. “If you were in a group at higher risk, then it might be difficult to modulate that risk,” says Dekhtyar. “But it’s not deterministic. We can clearly see that risk can additionally be reduced, just not by as much as if you started with a lower baseline risk.”

For doctors and people concerned about their dementia risk, especially those in families in which several members are already affected by the condition, it’s important to understand that protection against dementia begins early. And even if it’s too late to become more engaged in school, continuing to build cognitive reserve with an intellectually demanding job, staying socially active and mentally engaged, can be helpful as well. “It’s a good message that I think has to be out there for patients,” says Dekhtyar.

TIME Brain

How Alzheimer’s Is Different in African-Americans

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The brain disease looks very different in African-Americans than it does in whites, which could affect treatment and diagnosis

The hallmark signs of Alzheimer’s are well-established—plaques of amyloid protein and tangles of tau protein in the brain, which work to suffocate and eventually destroy neurons that are dedicated to higher level functions such as memory and reasoning.

But in a study published in the journal Neurology, researchers show that there may be important differences in the way Alzheimer’s appears in the brains of African-American and white patients. When Lisa Barnes, a neurologist at the Rush Alzheimer’s Disease Center at Rush University Medical Center and her colleagues compared the brains of 41 black patients who had died of the disease to the brains of 81 white patients, they found a much more complex picture of Alzheimer’s in the brains of the African-Americans.

MORE: Mental and Social Activity Delays the Symptoms of Alzheimer’s

These patients were more likely to have not just the familiar plaques and tangles, but also other signs of neurological abnormalities, including Lewy bodies, signs of infarcts and blood vessel disease. In fact, 71% of the African-American patients showed this mixed picture compared to 50% of the white patients.

The most common—and surprising, says Barnes—connection involved the Lewy bodies. These are clumps of proteins that aggregate inside nerve cells, particularly those involved in movement. They are common in Parkinson’s patients and can contribute to tremors as well as hallucinations and sleep disruptions. Because the black population is known to have higher risk of circulatory disorders, including stroke and hypertension, Barnes expected to find more infarct-related differences when comparing the brains of African-Americans to those of whites. “We did not find that,” she says. “We found a much more mixed picture than just infarcts, and that was a little bit surprising.”

MORE: Many Doctors Don’t Tell Patients They Have Alzheimer’s

She says, however, that the prevalence of Lewy bodies in the brains might simply reflect a bias in the study sample, since they came from the population of patients who came to the Alzheimer’s clinic. Hallucinations and abnormal movements are more likely to cause patients to see a doctor than slips in memory, which many dismiss as a normal part of aging.

Still, Barnes says the findings suggest that there may be important differences in the way Alzheimer’s develops in African-Americans that is being missed with the dominant focus on plaques and tangles. “They suggest that treatments currently on the market targeting plaques and tangles, if they are given to a population that has more mixed disease, may not respond as well to the medication,” she says. “Right now we are focused on amyloid and tangles. But maybe we need to be thinking about Lewy bodies and infarcts as possible treatment targets.”

It’s possible, for example, that in African-American patients, a combination of drugs that includes other medications to treat blood pressure or diabetes might be as important for addressing symptoms of dementia.

The results also suggest that having better ways of detecting not just the plaques and tangles but other changing brain abnormalities, particularly in non-white populations, are desperately needed. But Barnes says that little is known about how brain disorders evolve in different racial and ethnic groups because there are very few studies involving them. “We need to have better biomarkers—something to actually detect things in the body, blood and brain to help us see how the disease is playing out in different racial and ethnic groups,” she says. “But we need people participating in the studies to do that.”

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