Remember: The Science of Memory and the Art of Forgetting

by Lisa Genova

Memory is quite economical. In a nutshell, our brains have evolved to remember what is meaningful. They forget what isn’t. The truth is, much of our lives are habitual, routine, and inconsequential.

we often forget not because it’s efficient for our brains to do so but because we haven’t supplied our brains with the kinds of input needed to support memory creation and retrieval.

The average adult has memorized the sound, spelling, and meaning of 20,000 to 100,000 words.

The hippocampus binds your memories. It is your memory weaver. What happened? Where and when did it happen? What does it mean? How did I feel about it?

With an impaired hippocampus, people with Alzheimer’s have trouble creating new memories.

When I remember her, my brain is activating what she looked like in my visual cortex, the sound of her laugh in my auditory cortex, the smell of the sautéed green peppers and onions she cooked almost every day for lunch in my olfactory cortex,

Whenever we remember something, we are reactivating the various elements of the information we experienced, woven together as a single unit.

If we want to remember something, above all else, we need to notice what is going on. Noticing requires two things: perception (seeing, hearing, smelling, feeling) and attention.

We can only remember seven plus or minus two things for fifteen to thirty seconds in working memory.

We have three basic types of long-term memories: memory for information, memory for what happened, and memory for how to do things.

While semantic and episodic memories are consolidated via the hippocampus, muscle memories are bound together by a part of the brain called the basal ganglia

Episodic is personal and always about the past. Semantic memory is about information and is timeless. Just the facts, ma’am.

Life events infused with emotion are what we tend to remember long term—triumphs,

Emotion and surprise activate a part of your brain called the amygdala, which, when stimulated, sends powerful signals to your hippocampus that basically communicate this: Hey, what’s going on right now is super important. You’re going to want to remember this. Consolidate it!

game, the memories you share over and over with friends and family are not accurate records of what actually happened.

The Baker/baker paradox also explains why so many of us are bad at remembering names but not at recalling other details about a person.

We forget to do what we intended to do. A lot. Prospective memory is that flaky friend who likes to make plans with you to meet for drinks but half the time is a no-show.

But you still know how to do what you’ve learned—if only your aging body were still up to the task.

Don’t be overly impressed by the articulation of this email. It took about two hours to write. Years ago, I would have written this in five minutes or less. But it was worth the time.

We think it takes fifteen to twenty years of seemingly innocent amyloid plaque accumulation before it reaches a tipping point, then triggering a molecular cascade that causes tangles, neuroinflammation, cell death, and pathological forgetting.

Older memories already formed are safe for now, but new information that would normally be consolidated into a lasting memory by the hippocampus and available later for retrieval is lost.

logical thinking, decision-making, planning, and problem-solving. When Greg couldn’t reroute his thinking to a plan that involved wearing dry clothes instead of the wet clothes from the dryer, he was experiencing Alzheimer’s in his frontal cortex.

So grief, rage, and lust might become dysregulated and disinhibited.

Forgetting due to Alzheimer’s is pervasive, catastrophic, tragic, and not normal.

prospective (what you plan to do), episodic (what happened), semantic (information you know), and muscle (how to do things) memories.

Matching the context you’re in for recall with the conditions you were in when you learned the information improves recall.

Lacking effective tools to combat incessant stress, too many people fall victim to addiction and “deaths of despair.”

Chronic stress inhibits neurogenesis in the hippocampus. So if you’re experiencing unrelenting, unmanaged stress, you’ll have a smaller hippocampus, which means fewer neurons available to consolidate memories, which means your ability to create new memories will be impaired.

In a study of perceived stress levels in eleven hundred women aged thirty-eight to sixty over thirty-five years, women who reported experiencing chronic stress had a 65 percent increased risk of Alzheimer’s. In another study, people under chronic stress were twice as likely to develop Alzheimer’s disease as were people who felt less stress, and the chronically stressed people were ten times more likely to develop cognitive impairment over five years.

Insufficient sleep puts you at a higher risk for heart disease, cancer, infection, mental illness, Alzheimer’s, and memory impairment.

He drinks coffee just before he nods off for a twenty-minute nap. When he wakes up, many of his newly formed memories will have been consolidated into long-term, stable storage; his maxed-out hippocampus will have been somewhat cleared out, making room for whatever he needs to remember next; and the caffeine from his coffee, which takes about twenty-five minutes to enter his bloodstream, will almost have kicked in, activating his frontal cortex neurons to pay attention.

During deep sleep, your glial cells flush away any metabolic debris that has accumulated in your synapses while you were in the business of being awake.

A single night of sleep deprivation can lead to an increase in amyloid and tau (another predictive biomarker for Alzheimer’s) in cerebral spinal fluid. If you continue to get insufficient sleep, amyloid will continue to accumulate night after night, and you will be closer and closer to the dreaded tipping point—closer and closer to a diagnosis of Alzheimer’s.

Insufficient sleep is likely to be a significant risk factor in the development of Alzheimer’s.

Ninety-eight percent of the time, Alzheimer’s is caused by a combination of the genes we inherited and how we live.

Memory is everything and nothing.

This disease won’t steal Greg’s sense of humor, which he masterfully wields in every interaction I have with him. It hasn’t taken away his faith or his ability to be present or to have rich relationships with other people. Greg’s memory sucks, and he’s one of my best friends. He has a family he loves and who love him, and he’s still living a memorable life that matters.

But even on the day she died, she knew she was loved. She didn’t know who we were, but she loved us back.