May 18, 2019

Axios Deep Dives

Memories — joyful, painful, useful or even deceptive — carry the experiences of our lives.

  • This special report — by Axios' Alison Snyder, Jessie Li, Eileen Drage O'Reilly and Kaveh Waddell — looks at advances in understanding memory, what happens when it goes awry, and what might be done to maintain and even manipulate it.
1 big thing: The future of forgetting

Illustration: Aïda Amer/Axios

We are desperate to fight forgetting — it scares us, it annoys us and it can cost us.

Yet there are also memories we want to forget.

  • And day to day, we're able to learn, make decisions and move through life because the brain balances forgetting irrelevant information and experiences, with remembering important ones, Alison writes.

What's happening: Rather than being a flip side or failure of memory, forgetting is being studied as a brain process in its own right.

  • Psychologists have studied forgetting for decades, including how we control our memory by substituting thoughts or by directing some attention, but not too much, to an unwanted memory.

Now, neuroscientists are starting to figure out how the brain forgets.

  • Neurons represent memories as patterns of firing between themselves in the short term. In the long term, they're etched in connections between neurons that strengthen with repeated firing.
  • Like remembering, there may be different ways the brain forgets — memories can fade over time if connections between neurons weaken, or similar memories may interfere with one another.

A flurry of recent papers and media suggests the brain also actively forgets — when retrieving memories or learning new information.

  • It could even be the default state of the brain, proposes Ronald Davis, a Scripps Research Institute neurobiologist who studies forgetting in fruit flies.
  • Soon after a new memory is formed, he says, the neurotransmitter dopamine acts as a "forget" trigger in a cascade of chemical changes known to affect the connections between neurons. Memories deemed important are stabilized, others aren't.

What's next: As Alzheimer's disease drug trials fail and projected costs of dementia rise, researchers want to home in on new molecules to target for treatments, but Davis cautions it is early days for aspirations of altering forgetting with drugs.

Meanwhile, psychologists want to study the brain's forgetting strategies to improve therapies for post-traumatic stress disorder and other conditions.

  • This isn't "Eternal Sunshine of the Spotless Mind" zapping memories out of people's heads, says Jarrod Lewis-Peacock, a professor of psychology at the University of Texas at Austin.
  • Rather, it is figuring out how to help people put their memories into "a mushy state" where they can be updated or reassociated with more positive things.


2. AI needs to forget

Illustration: Aïda Amer/Axios

For artificial brains, striking the right balance between remembering and forgetting is essential to leapfrogging some of the biggest hurdles still ahead in AI, Kaveh writes.

Without a special mechanism to store information for later, AI is prone to what's known as "catastrophic forgetting." When learning a new task, it can lose the ability to do an old one, like a language learner forgetting their native tongue.

  • Some researchers are adding in memory modules that can set aside learned patterns, so that they don't get overwritten by new information.
  • Others, like Dileep George, founder of the AI company Vicarious, are experimenting with turning specific tasks into computer programs that are walled off from others and can be combined to perform more complex jobs.

These help with AI's forgetting problem — but they're not how human brains work, says Blake Richards, a neuroscientist and AI researcher at the University of Toronto.

  • What our brains actually do isn't completely clear, says Richards, but memories are likely distributed across the brain. That may be at the root of our ability to imagine and plan — two essential qualities that AI still lacks.
3. The quest for Alzheimer's drugs
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Adapted from a PhRMA analysis of the Adis R&D Insight database on investigational drugs in various stages of clinical development; Chart: Axios Visuals

Time after time, drug companies have struck out in trials looking to prevent or even slow Alzheimer's disease and are turning to fundamentally different approaches, Eileen reports.

The biggest problem: Scientists still don't know the cause of the disease, currently affecting 5.7 million Americans.

  • What is known: More women than men get the disease, there are genetic risk factors, and there are 3 hallmarks — neurons are lost accompanied by brain shrinkage, there is an increase in beta-amyloid proteins leading to "plaques," and large numbers of tau proteins creating "tangles."

For decades, research and drug trials have focused on those proteins — but so far none have panned out.

Here are some of the approaches researchers are now taking:

Beyond medicine and genetics, researchers want to leverage modifiable risk factors like sleep, cardiovascular disease and blood pressure.

  • The World Health Organization issued guidelines earlier this week making recommendations for everyday life to reduce the risk of cognitive decline and dementia.
4. Deepfakes and false memories

Illustration: Aïda Amer/Axios

There’s remembering. There’s forgetting. And then there’s false memory, our memory of an event that never actually happened, Jessie writes.

How it works: Our memory system often fails not only because we forget things that happen, but also because we remember things that didn't happen, says Duke University neuroscientist Roberto Cabeza.

  • Using brain imaging, he found that high confidence for true memories was associated with greater activity in a different part of the brain than for false memories.

What's new: In an age of deepfakes and doctored photographs, misinformation can subtly sculpt our memories.

  • Even blatantly doctored photographs — with written disclaimers — of the 2012 London Olympic torch relay and the 2011 royal wedding led a subset of viewers to believe more violent protestors had been present and more people were arrested at these events than actually were.

Yet planting false memories isn't necessarily a bad thing, according to Elizabeth Loftus, a cognitive scientist at UC Irvine.

  • Loftus found subjects who were led to believe they loved asparagus as children subsequently were more interested in eating asparagus at a restaurant and were willing to pay more for asparagus in a grocery store.
5. How memory changes as we age

Illustration: Aïda Amer/Axios

About 11% of Americans over the age of 65 are diagnosed with Alzheimer's disease and related dementia.

For others, changes in memory are normal as people age, Alison writes.

How it works: Different kinds of memories are formed, stored and maintained in and between different regions of the brain, but the hippocampus is a central player.

  • As people pass 60 years of age, they often experience a decline in episodic memory, or autobiographical experiences, which some research ties to changes in the hippocampus.
  • The upside is that semantic memory — our knowledge about the world — declines later in life, says Michael Rugg, a memory researcher at the University of Texas at Dallas.

What's next: There are individual differences in when and how fast cognition changes as we age. Researchers want to understand them in hopes of tailoring treatments to maximize brain function.

  • Neuroscientist Carol Barnes of the University of Arizona tells Axios she envisions a field of "precision aging" — applying the approaches of precision medicine to cognitive health by studying factors like genetics, environmental exposure and social interactions in a large, diverse group of people over time.
6. Your brain is a big business
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Note: Some totals don't add to 100% due to rounding; Data: SurveyMonkey poll of 2,360 U.S. adults conducted May 5–8, 2019, with a margin of error of ±3 percentage points. Poll methodology; Chart: Axios Visuals

Memory supplements claiming to ward off cognitive decline abound, but the evidence is lacking.

"People are willing to pay and do anything to preserve their brains ... but we don’t have the knowledge yet to give really effective interventions that change that trajectory as much as people think."
— Joanna Hellmuth, neurologist, UC San Francisco

The big picture: The business of memory supplements — from branded regimens to vitamins — pulled in $3.2 billion globally in 2016.

"The problem is that a lot of the interventions being marketed directly to consumers don’t do rigorous studies of the outcomes," says Hellmuth, who recently wrote about the "rise of pseudomedicine" for brain health.

Go deeper: Brain training games and wearable brain devices targeting memory are also under scrutiny.

7. 1 extraordinary thing: The two extremes of memory

Illustration: Aïda Amer/Axios

Most people can rely on some aspects of memory, but some live on the extremes, Jessie writes.

“You can ask them about any day in their life,” James McGaugh of UC Irvine says about people with highly superior autobiographical memory (HSAM), which he discovered in 2000 when a woman named Jill Price wrote to him:

"Whenever I see a date flash on the television, I automatically go back to that day and remember where I was, what I was doing, what day it fell on and on and on and on and on. It is non-stop, uncontrollable and totally exhausting.”

Those with HSAM retrieve memories more rapidly, and certain brain regions are more active in them than in adults who don’t have the condition.

  • The total known number of people in the world with HSAM today is around 120.

The flip side: Susie McKinnon doesn’t remember any events from her life. She doesn't remember any vacations she's taken. She doesn't remember herself as a kid.

  • McKinnon emailed University of Toronto neuroscientist Brian Levine in 2006 about her condition, and is the first person identified with severely deficient autobiographical memory (SDAM).
  • Many people with SDAM say they can’t form images in their heads, something Levine plans to investigate further with brain scans.

What’s next: People with memory abnormalities suggest the possibility that we all have the potential ability for conditions like HSAM in our brains, McGaugh says.

  • “That’s the future of brain research, exploring what the potential is of the brain, not just what it’s like for ordinary people.”