A Scientist Explains How Brains Form Memory—and What Causes Memory Loss

There are so many reasons—normal, non-scary reasons—why we forget things, whether it’s the name of that dog-walking neighbor, or our friend’s birthday, or where we parked our car. Sometimes we’re moving at too fast a pace, multi-tasking all the way. Or maybe our lives are full of too much stress and too little sleep .

Of course, there are more serious and definitely scary-to-consider reasons why people become forgetful—and those are the ones we worry about. The fear is understandable, given the constant flow of news about dementia , as well as our own possible experiences with loved ones.

To understand more about memory , memory lapses, and cognitive dysfunction, here’s a look at how a memory is created in the brain, as well as what’s happening when a person’s recall starts to slip. How a memory is formed

Let’s say you walk in the door and put your keys down next to the coffeepot. “When you do that—when you have any experience—a certain pattern of activity happens in specific neurons (or nerve cells ), and specific neurons are activated,” says neuroscientist Tara Tracy, Ph.D ., assistant professor and a specialist in neurological decline at the Buck Institute . “The strength of those neurons’ activity will affect how well you remember it later. In order to form a memory, there needs to be a strong activation of the neurons, and then there needs to be a plasticity effect—meaning, there needs to be some kind of little change in the brain.” ( Plasticity refers to the brain’s ability to make new neural pathways, and change the ones that already exist, in response to changes in your behavior and environment.)

But maybe when you drop those keys next to the coffeepot, there’s a lot going on in your mind: You’re thinking, I have to gas up the car when I go out again, and whoa, this floor needs washing, and did anyone pick up the dry cleaning? while you’re simultaneously putting away the groceries and glancing at a text. In that case, says Tracy, there’s a good chance that the neurons were only weakly activated. Then, it’s much more likely that you’re going to forget later where you left your keys, she says, “because a weakly activated neuron will not encode the information as well in the brain. There won’t be that plasticity effect when the neurons are only weakly activated.”

This is something that Tracy’s lab at the Buck Institute is focusing on: the “little change in the brain” that allows the memory to encode. “We think this is happening at the synapses , the connections between neurons,” she says. “When the neurons get activated during an experience, synapses within a certain region of the brain will start to strengthen. And that strengthening is what we think encodes the memory.” Lifestyle and memory

How you go about your days and nights can have a definite impact on your memory. For example:

Sleep is seen to be critical to how our brains store memories, though researchers aren’t entirely sure why; those quiet hours seem to give the brain the chance to consolidate memories, as well as to clear toxins and waste products.

Exercise , especially when it’s moderate to vigorous, was found in a large, long-term study to improve memory as well as overall cognition. Exercise helps your brain form more connections between neurons, among other things. The CDC recommends 150 minutes of moderate activity a week—and points out that short bouts of movement add up.

Stress has been shown in multiple studies to affect how our brain stores and retrieves memories. When you’re under high stress the body releases the hormone cortisol, which affects parts of the brain involved in the processing of memory. When cognition declines

“Some loss of cognitive function— age-related cognitive decline —is normal at a certain point,” says Tracy. Everyone experiences it as they get older, to some degree or another.

According to Mayo Clinic , another stage is mild cognitive impairment , in which people may have issues with memory, finding the right words, or impaired judgment, but they usually can go about their usual life. They, or their loved ones, may notice that they’re not able to track conversations or the plot of a film as well as they used to, or they may get disoriented even in places they know well or are more forgetful than they previously were. There’s no single cause for mild cognitive impairment, and it may get better or worse over time.

When it comes to dementia, Alzheimer’s disease is the most common form , accounting for 60-80% of cases, according to the Alzheimer’s Association . Scientists around the world are working to prevent and treat it.

Tracy’s lab at the Buck Institute is studying memory loss from Alzheimer’s disease and frontotemporal dementia. “Everybody experiences normal age-related cognitive decline, not just people with a disease,” she says. “And so the question is, what are the underlying mechanisms of cognitive aging versus Alzheimer’s disease? Are they the same or different?”

There’s overwhelming evidence, Tracy points out, that Alzheimer’s disease is driven by toxicity in the brain caused by a build-up of two proteins, beta-amyloid and tau. “This build up doesn’t necessarily happen in many people who just have age-related cognitive decline,” she says. “That suggests that the mechanisms are different in each.”

There are similarities, however. “Our research is suggesting that in age-related cognitive decline, and especially in Alzheimer’s disease, the neurons can still be activated in the early stages of memory loss, but the synapses can’t encode,” she explains. “There still is neural activity but the synapses can’t encode it. That’s a separate mechanism.”

Alzheimer’s disease is a progressive disease, Tracy points out; people can live with it for five to ten years, sometimes longer. “In the early stages people’s lifestyle can really be affected, but they probably still remember their family members and can do some things—it’s not severe dementia,” she says. “When it gets to the later stages , when it is severe dementia […]

Read more at www.prevention.com