As NBC’s stellar series, “This is Us,” premiered last week, we learned more about Rebecca Pearson’s battle with mild cognitive impairment, or MCI. Pearson, played by actress Mandy Moore, suffers from a condition that is common in our country and characterized by cognitive changes that are serious enough to be noticed by friends and family.

Approximately 15% to 20% of people over the age of 65 have MCI, according to the Alzheimer's Association. People with MCI, especially MCI involving memory problems, are more likely to develop Alzheimer’s disease or other dementias than people who do not have this condition. However, MCI doesn’t always lead to dementia, as many people fear and believe. In fact, MCI is not always permanent.

“It depends on the underlying cause,” says Dr. Joel Salinas, a neurologist at Harvard-affiliated Massachusetts General Hospital, according to the Harvard Health Letter. Here are some underlying causes of MCI:

• Degenerative brain disease, such as Alzheimer’s disease
• Stroke or other vascular disease
• Traumatic brain injury
• A medication side effect
• An underlying health problem such as sleep deprivation, depression, or anxiety

The American Academy of Neurology (AAN) recently published new guidelines for the treatment of MCI and notes that about 15% of time MCI cases progress into full blown dementia. Dr. Salinas adds that when the cause is a neurodegenerative disease, the numbers of those who progress into dementia will be higher. What is unclear is how long, if ever, this progression takes.

“If the cause is Alzheimer’s disease, it may two to five years,” he says. “But I’ve seen patients stay in the MCI stage for many years, even when we presume it was a neurodegenerative disease.”

Salinas says that MCI can often be reversed if a general health condition such as sleep deprivation is causing the decline. By treating the underlying cause, cognition dramatically improves.

The AAN has found encouraging evidence linking exercise with better memory in people with MCI. Exercising can offer both mental and social stimulation while improving blood flow to the brain. This increased blood flow may also release molecules that can repair brain cells and make connections between them and so the new guidelines recommend exercising at least twice a week. Cognitive tasks like operating a computer or playing video games can also sharpen your brain’s response time and improve attention span.

Salinas advises people with MCI to emulate the healthy habits of older adults by adding mentally stimulating activities like taking up a new hobby or learning a new language and also talking to their doctors about the medications they are taking to help stave off dementia.

There are no guarantees, but the evidence does suggest that these steps may delay or even prevent progression to dementia.

“The people who spend the most time cognitively stable are often the ones who stick to healthy lifestyle recommendations,” he says.

One of the more recent and successful treatments for MCI is a 10-day, intensive program developed by the Mayo Clinic is called HABIT — short for Healthy Action to Benefit Independence & Thinking. It relies upon healthy lifestyle strategies to help delay or prevent MCI from progressing to dementia, according to AARP.

Developed by Dr. Melanie Chandler, patients are taught techniques such as yoga, mindfulness, brain fitness, healthy eating habits, and how to tackle important legal tasks that are often neglected, such as designating power of attorney. They are also shown a note-taking system that can stand in when their memory fails.

“We know from psychological research that when people write things down, they tend to follow them betters,” says Chandler. “and there is a sense of ownership if you’ve committed to something in writing that you plan to do.”

People with MCI who did not go through the HABIT program showed a steady decline in cognitive functioning, while those who went through the Mayo program, remained about the same.

“These folks are maintaining,” says Chandler, according to AARP.