Understanding hyperthymesia

Do you remember what you had for dinner two years ago today? What about two weeks ago? Most of us don’t have a clue. But a small number of people, including a California woman named Jill Price, can remember such events in great detail. They have a condition called hyperthymesia syndrome. This is often referred to as highly superior autobiographical memory (HSAM).

Neurobiologists at the University of California, Irvine coined the term hyperthymesia to describe Jill Price’s remarkable memory. In extensive testing, she demonstrated the ability to recall details of events that happened on specific days, spanning decades of her life. Researchers were able to verify many of her memories.

To date, only a small number of people have been diagnosed with HSAM. Research is growing, as scientists hope to learn more about the ways circuitry in our brains processes memory. This has the potential of helping people with impaired memory, such as people who have amnesia or have had a brain injury.

When you experience something, your brain stores it as a short-term memory. You probably remember what you wore yesterday, but that memory will fade quickly. If the experience was meaningful, it may be stored indefinitely as a long-term memory. Most people remember where they were for a marriage proposal or their first kiss. Short- and long-term memory are stored in different areas of the brain.

People with HSAM process short-term memories the same way as most people do. But researchers have found that, unlike most people, the accuracy and detail of memories improve over time in people with HSAM.

The type of memory associated with HSAM may be called autobiographical memory or eidetic memory. People with this type of memory recall events, images, dates — even conversations — in minute detail. And they’re able to summon these memories effortlessly.

People with HSAM can often remember things that happened when they were small children. But memories of events that occurred after the ages of about 10 or 12 are more vivid and detailed.

When researchers studied Jill Price (under the pseudonym AJ), they asked her about events on specific days. She almost always answered correctly. After several years of research, they asked if she remembered dates of her appointments with them. Without pausing, she rattled off those dates correctly.

Autobiographical memory is different than other kinds of memory, such as the following:

Mnemonic memory

Have you ever used a rhyme or song to help you remember something? Many children learn the alphabet with the ABC song. The type of memory used for this is mnemonic memory. People with exceptional autobiographical memory don’t use mnemonics to memorize details of their lives. In fact, some report that rote memorization, such as using repetition to remember things like the multiplication tables, is difficult for them.

Flashbulb memory

Flashbulb memory is like a very vivid snapshot of a moment in time or an event. Most people can envision seeing live coverage of the planes hitting the World Trade Center on September 11, 2001 or the photo of the President and Mrs. Kennedy riding in the convertible in Dallas the day he was assassinated. People with HSAM have more than flashbulb memories; they see full series of events.

Implicit memory

The ability to do things automatically, without thinking, is because of your implicit memory. This type of memory enables you to do things you previously learned like ride a bike, use a stick shift, or type on a keyboard. People with strong autobiographical memory also have implicit memory, but the two are not directly related.

People who have been diagnosed with HSAM represent a variety of ages, walks of life, and levels of intelligence.

Several traits, though, appear to be common across those affected.

They may spend a lot of time thinking about things that happened to them in the past.

They have the ability to concentrate deeply, blocking out distractions in the environment around them.

Alternatively, they can be easily distracted by their memories and lose focus on things going on around them. They’re more likely to daydream and fantasize.

Many people with HSAM have large collections that they’ve organized and cataloged with great care. This may evolve into compulsive behavior.

It’s not understood why some people have HSAM. By taking images of the brain, though, researchers have noticed that some parts of the brain structure of people with HSAM are different than those of people who have typical memory function.

However, it’s not known if these differences caused the HSAM or if they occurred because of the person’s greater use of areas of the brain associated with memory.

Ongoing research on memory will increase our understanding of HSAM’s causes.

Scientists use brain imaging tests such as MRIs and electroencephalograms to diagnose and study memory in people with HSAM.

Tests are also done to help measure memory. One of the most common is the autobiographical memory test. In this cued recall test, participants receive positive and negative cue words to prompt a memory. When a memory comes to mind, specific emotional and contextual details are written down, counted, and scored.

Another version of this test skips providing cues. Participants receive minimal instructions. As with the cue-recalled test, details are written down, counted, and scored.

If you are diagnosed with HSAM, your doctor will work with you to develop a management plan.

Although HSAM doesn’t carry any physical side effects or complications, it can be mentally exhausting to absorb and store so much information. Your doctor can advise you on coping mechanisms and answer any questions you may have.

HSAM can be both a gift and a challenge. People with keen autobiographical memory skills remember the bad times in addition to the good times. Although some people report struggling with memories cluttering their thoughts, most learn to focus on the good memories.

Learn more: How much of our brain do we use? »

Your memory might not qualify for HSAM status, but there are things you can do to improve it. Here are a few tips:

  • Get enough sleep. Being sleep deprived directly impacts your ability to remember things.
  • Stay active. Moderate-intensity exercise can improve your memory and may even increase the size of the part of your brain involved in memory. One recommendation is brisk walking for at least 2 1/2 hours each week.
  • Give your brain a workout, too. In addition to exercising your body, exercise your brain and sharpen your memory with activities like reading, doing crossword puzzles, playing cards, memorizing songs or poems, playing a musical instrument, or learning a foreign language.

Want to remember a specific event better? A recent study found that exercising four hours after the event may help you retain the memory better. Exercising immediately after the event had no effect.

After adding some brain-boosting behaviors to your routine, you can test your memory to see if there are any improvements.

Give one of these self-tests a try:

Keep reading: Left brain vs. right brain: What’s the difference? »