Testing how well people remember past events in their lives could help medical professionals make early predictions about who is at risk for developing Alzheimer’s disease (AD), according to a new study from the University of Arizona.
Researchers administered an “autobiographical memory” test to a group of 35 healthy adults, about half of whom carry the gene variant APOE e4–a known genetic risk factor that nearly doubles the chances of developing AD. As a group, those with the genetic risk described memories with much less detail than those without it, says ScienceDaily.
Sometimes called a disease with a clinically silent beginning, Alzheimer’s is difficult to detect early even though changes in the brain related to the disease may begin to happen years or even decades before an individual starts to exhibit memory difficulties, said UA neuropsychologist Matthew Grilli, lead author of the new research, which is published in the Journal of the International Neuropsychological Society.
“This raises a huge challenge for developing effective treatments,” said Grilli, an assistant professor and director of the Human Memory Laboratory in the UA Department of Psychology. “The hope is that in the near future we will have drugs and other treatments that could potentially slow down, stop and even reverse some of these brain changes that we think are the hallmarks of Alzheimer’s disease. The problem is that if we can’t detect who has these hallmarks early enough, these treatments may not be fully effective, if at all.”
Grilli’s goal is to help pick up on brain changes much earlier, before they begin to have an obvious effect on cognition and memory. He and his UA colleagues Aubrey Wank, John Bercel and Lee Ryan decided to focus on autobiographical memory, or people’s recollection of past events in their lives, because this type of memory depends on areas of the brain that are vulnerable to early changes from Alzheimer’s disease.
“When we retrieve these complex types of memories that have multimodal details, they’re highly vivid or rich; they come with narratives, context and backstories,” Grilli said. “We’ve learned through cognitive neuroscience that the ability to recreate these memories in your mind’s eye depends on a widely distributed network in the brain, and it critically depends on regions of the brain that we know are compromised early on in Alzheimer’s disease pathology.”
In autobiographical interviews, study participants, who ranged in age from early-50s to 80, were asked to recall recent memories, memories from their childhood and memories from early adulthood with as much detail as possible. The interviewers–who did not know which participants had a genetic risk factor for Alzheimer’s–recorded and scored participants’ responses, evaluating which details added to the richness and vividness of the memories and which did not.
Those with the genetic risk factor for Alzheimer’s disease, as a group, described memories with much less vivid detail than those without the risk factor, despite the fact that all study participants performed normally and comparably on a battery of other, standard neuropsychology tests.
“None of these individuals would be diagnosed with dementia or mild cognitive impairment (MCI),” Grilli said. “They are clinically normal, they are cognitively normal, but there’s this subtle difficulty one group has with retrieving real-world memories, which we think is because there are more people in the group who are at a preclinical stage of Alzheimer’s disease.”
Not everyone with the gene variant APOE e4, which is present in about 25% of the population, will develop Alzheimer’s disease, and not everyone who develops Alzheimer’s has the gene.
“From this study, we can’t identify one person and say for sure this person is in the preclinical phase of Alzheimer’s disease. That’s the next stage of work that we need to do,” Grilli said. “But we know that as a group there probably are more people in the e4 carrier group that are in the preclinical phase of Alzheimer’s disease, and we think this is why they had a harder time generating these memories.”
Grilli said the next step is to study brain activity in the people who struggle to generate vivid autobiographical memories to see if they have observable changes in brain structure or activation of the regions of the brain affected early on by Alzheimer’s.
The hope is the work could lead to the development of a clinical test sensitive enough to the preclinical brain changes of AD that could be used to identify people who should undergo more extensive testing for early Alzheimer’s disease pathology.
“The tests for early signs of Alzheimer’s disease pathology are invasive and expensive, so this new cognitive test potentially could be used as a screen,” Grilli said. “It also could be used to help clinical trials. At the moment, it’s very difficult and expensive to conduct clinical trials of new drugs because it takes a very long time to determine whether that drug has had an impact on memory.” He added, “If we have more sensitive measures, we might get answers sooner, especially if we’re trying to administer drugs before obvious signs of memory impairment are detectable.”
I recently returned to San Diego from a 2-week working “vacation” to northern Michigan and the Washington, DC area. The trip brought me together again with a large assemblage of friends, relatives…and myself.
Prior to leaving, I had just read the foregoing piece on autobiographical, or what I would term “first-person” memory, and the correlation with early onset dementia and, ultimately, Alzheimer’s. Most of the people I interacted with fell into the age range of 60-80 years.
I decided to conduct my own entirely unscientific study and found that the group was roughly divided between those who had childhood memories with vivid descriptions and those who didn’t. The former recalled family trips that included detailed recollections of events like specific games played in the backseat of a car and minutiae such as frozen bologna sandwiches and stops along the New Jersey Turnpike at various Howard Johnson’s for hotdogs on a wedged, toasted, buttery bun and a Coke.
By sharp contrast, a few had little or no recollection of such personal events, not that it had any neurological significance. (I’m certainly not a clinician in this realm.)
However, I thought it might be useful to shed some additional light on the term “autobiographical memory” by one particular KOL, who’s written extensively on the subject at her website, “About Memory.” Her name is Fiona MacPherson, PhD, a professor of philosophy at the University of Glasgow.
The following is Dr. MacPherson’s take on the topic, wherein she defines and distinguishes the various classifications of memory.
Autobiographical memory contains information about yourself and about personal experiences. Emotions–the “facts” that describe you and make you unique, the facts of your life and the experiences you have had–are all contained in separate domains, and processed differently. Your memory for emotions can help modify your moods.
Specific events you have experienced are only memorable to the extent that they include details special to that specific occasion. Most events in our lives are routine, and are merged in memory into one generic memory containing the common elements of the experience.
1) Autobiographical memory includes several domains: self-description (the source of a large part of your sense of identity), containing information such as whether or not you like ice-cream; what your favorite color is; what you think about a political party.
By dwelling on appropriate memories, we can sustain a mood. By recalling memories that involve a contrasting emotion, we can change a mood.
2) Your memory for events
This is the largest component of autobiographical memory, containing three separate but related domains:
- Memory for specific events that have happened to you;
- Memory for general events, which tells you the broad sequence of actions in events such as going to a restaurant or going to the dentist; and
- An abridged summary of your life, which enables you to answer such questions as, “Where did you go to school,” and “where were you working last year?”
3) Recalling specific events
Event memory is usually entered via the general-event level, although the information being sought is usually at the specific-event level. Thus, if you’re trying to retrieve the memory of going to see the movie Titanic, you will probably start by accessing the general event, “going to the movies.”
Specific events over time become merged into a general event–all the occasions you’ve been to the dentist, for example, have blurred into a generic “script,” which encapsulates the key experiences and actions that are typical of the going-to-the-dentist event. After the specific event has become consolidated into the script, only distinctive events are likely to be specifically remembered. That is, events when something unusual/interesting/humorous happened.
The power of these scripts is such that people often “remember” details of a specific event that never happened, merely because they are typical of the script for that event.
Our memory for events reflects what we expect to happen. It is perhaps because of this that unexpected events and new events (first-time experiences) are better remembered. If you don’t have an existing script for the event, or if the event is atypical enough not to easily fit an existing script, then you can’t mold the experience to your expectations.
The more distinctive an event–the more the event breaks with your script for that type of event–the better your memory for that particular event will be. (Failures to remember trivial events, such as where you’ve put something, or whether you’ve done something, are reflections of the fact that we pay little attention to routine actions that are, as it were, already scripted.)
To remember an event therefore, you should look for distinctive details.
Having fretfully plumbed my own autobiographical memory, I am happy to report that I not only recall the card games, frozen bologna sandwiches and hot dogs at Howard Johnson’s but also how stinky the air smelled as we drove through the industrial portion of the New Jersey Turnpike. If that isn’t a distinctive detail, I don’t know what is. Oops.