You walk into a room and can't remember what you went there for. You forget someone's name. You can't recall the word for something.

Is it the normal forgetfulness that goes with aging, or something more serious?

Researchers now view dementia as similar to cancer, in that it is actually many diseases under a one-name umbrella. One of their goals is earlier detection, which could aid in managing the disease.

David Wolk, codirector of the Penn Memory Center, recently spoke to us about dementia and Alzheimer's disease — and the single lifestyle change we all should make to help keep our brains in shape. He also is an associate professor of neurology at the Hospital of the University of Pennsylvania and is on the faculty of Penn's Center for Cognitive Neuroscience.

What's the difference between age-related memory loss, dementia, and Alzheimer's?

The metaphor I use is that dementia is fruit, and Alzheimer's is apples. Dementia is a generic term for when, clinically, someone has significant change in their thinking, enough that it's impacting their day-to-day function in a significant way. Alzheimer's is a specific kind of dementia.

All of us, as we get older, probably starting in our 40s and 50s, begin to have some decline in some aspects of memory and speed of processing. It's common to have difficulty retrieving words and memories.

Given that most of these neurodegenerative diseases, in particular Alzheimer's, also affect memory, the early signs can be difficult to differentiate from normal aging. However, in normal aging, when you have trouble coming up with a word or memory, it eventually comes to you. It just takes you longer. But people with Alzheimer's tend to lose the information more completely. Another example is cueing. In normal aging, if you can't remember a detail of a prior event, such as what you ate at a restaurant, but someone gives you a cue, you often get it. You certainly recognize it when you are told it. With Alzheimer's, there's no getting it.

Why is early diagnosis important? 

Partly, we're trying to figure out if there is something we can treat. Treatable causes of dementia include vitamin deficiency (B12 is the classic one), thyroid dysfunction or infectious or inflammatory processes.

If it's a neurodegenerative condition that causes injury to the brain over time —Alzheimer's disease is the most common — there are only modest treatments. But diagnosis can influence management and prognosis. This is important. People want to know what to expect. All these conditions have different courses. They affect different aspects of thinking and/or motor symptoms. They are potentially more or less responsive to symptomatic medicines.

Early diagnosis allows people to plan — where they want to live, how they want to be cared for. The earlier you catch the disease, the more the patient can participate in that decision-making. If someone is having memory problems, it's important for those around them to know so safety measures can be put in place. If there are other medical conditions, it's important for a spouse or someone else to go to the doctor with them, to make sure they're not missing something that might affect their health. Another big area that is becoming more and more obvious is with regard to financial information — making sure that mistakes aren't made in bill-paying or investments.

Are there new ways to make diagnoses?

The field has moved to try to diagnose people at earlier stages. The problem is that by the time someone is traditionally diagnosed, there may already be brain changes and brain injury. Neurons and brain cells are damaged and dying in conditions like Alzheimer's disease. But as we try to diagnose earlier, the subtle differences between normal aging and the disease become much more difficult to sort out.

One tool is more rigorous cognitive testing. Typical bedside five-minute screening tests don't help us.

Also, in the last decade, we have developed tools that are quite good at detecting the brain changes and the molecular pathology of Alzheimer's disease. With MRI scans, we can see evidence of shrinkage, or atrophy, in the parts of the brain that are involved in memory. We now have PET scans that help us see the underlying pathology of Alzheimer's disease — in  particular, the  amyloid plaques, which are buildups of protein around the brain's nerve cells. They are thought to be one of the most important drivers in the disease process, so amyloid PET scans have been a real revolution in the research world.

We can also measure changes in spinal fluid through lumbar punctures.

However, PET scans are expensive. And lumbar punctures are mildly invasive. So the holy grail is to have some easier test — a blood or urine test — for detecting the disease. It's an area of active research.

What's on the horizon? 

These amyloid PET scans have been shown to be able to detect the disease in people even before they have symptoms, maybe even 10 to 15 years before. A number of drugs that specifically target the proteins that build up in the brain are in various stages of clinical trials. Many of these studies are focusing on people with minimal or no symptoms yet. Our hope is that these tests will show us who should get drugs that will prevent them from ever getting the disease.

What's the best way to maintain a healthy brain as we age?

There are a number of lifestyle factors that influence how our brain ages.  One is related to cardiovascular health. Heart disease tends to go along with having some degree of vascular disease in the brain. And the more vascular disease you have in the brain, the more likely it is, if you're going to get Alzheimer's, that you'll have symptoms sooner. Just as you protect your heart by maintaining normal blood pressure and not having high cholesterol, those help the brain as well.

Out of all the lifestyle things people can do, the one that most consistently shows a benefit in maintaining cognitive function is regular physical exercise. In particular, aerobic exercise. There are remarkable data showing that, even in adults with normal cognitive abilities, if some do aerobic exercises and others do stretching exercises, over time the people doing the aerobic exercises will show not only a lack of decline in their memory, but also some improvements in their memory and speed of processing.

We tell our patients that exercising 30 to 40 minutes a day, at least four days a week, is the most beneficial way to reduce their risk of memory and thinking issues.

That said, keeping yourself socially and mentally stimulated seems to be a benefit as well. I don't think there's good evidence that any particular kind of mental stimulation is better than another, such as crossword puzzles vs. Sudoku. But being mentally active is important. There are also data to suggest that the more social connectedness people have, the less likely they are to develop cognitive changes and dementia.