If there is one constant in medicine, it's change. Remember when we thought all ulcers were caused by stress? Now we know the majority are caused by a treatable bacterium.

The same transformations have been occurring in neurology. To learn how the field has changed, we talked to experts in five of the most common neurologic conditions—Alzheimer's disease (AD), epilepsy, migraine, multiple sclerosis (MS), and Parkinson's disease (PD)—about changes in our understanding of these diseases over the past 30 years.

"The biggest change is that neurology has made a transition from being a primarily diagnosis-related specialty to being a treatment-related specialty," says Richard B. Lipton, MD, director of the Headache Center" href="https://www.montefiore.org/headache-center" target="_blank" rel="noopener">Montefiore Headache Center at the Albert Einstein College of Medicine in New York and a Fellow of the American Academy of Neurology (FAAN). "And that's a huge measure of progress."

Alzheimer's Disease

Thirty years ago, dementia or Alzheimer's disease was the primary diagnosis for nearly everyone with severe memory loss, neurologists tell Neurology Now. Not today. Neurologists now know there are many different types of dementias, requiring different therapeutic approaches.

Neurologists are better able to differentiate the dementias, thanks to an explosion of new diagnostic tools and technologies in the past 30 years. "We've gone from ruling conditions out to getting better at ruling in AD," says Kostas Lyketsos, MD, director of the Johns Hopkins Memory and Alzheimer's Treatment Center in Baltimore, MD. Advanced brain imaging technologies—magnetic resonance imaging (MRI) and positron emission tomography (PET)—provide more sensitive measures of brain volume and changes in key brain structures, and help differentiate AD from other dementias. The ability to measure biological changes in spinal fluid has also helped improve the diagnosis of AD.

None of the existing therapies can stop or alter the course of Alzheimer's disease. But there has been a sea change in thinking about how and when the disease starts. Thirty years ago, neurologists thought of AD and dementia as diseases of aging. They would look for obvious memory loss and other declines in mental functioning to diagnose moderate to severe dementia, Dr. Lyketsos says.

But today, scientists believe the disease may develop in the brain decades before these symptoms emerge, and that treating it at that later stage may be too late. So researchers are focusing on looking for more subtle changes in mental functioning years before symptoms first appear, with an eye toward preventing or slowing the disease.

For example, three major prevention trials are underway in the U.S. to evaluate therapies that clear or break up amyloid plaques—deposits of protein fragments in the brain, which are one of the disease's hallmarks. They are enrolling people with a known genetic disposition for the disease—who either have a family history of the disease or have a known gene mutation that puts them at risk for the disease—as well as those who have evidence of the plaques on PET scans.

There is much greater awareness that the risk for developing AD and similar dementias can be reduced through improved health in general, Dr. Lyketsos says. Today, the conventional wisdom is that what's good for the heart is good for the brain. It is known that the same risk factors for heart disease and stroke—high blood pressure; elevated levels of low-density lipoprotein, the so-called "bad" cholesterol; diabetes; smoking; and obesity—can increase the risk for dementia. If you maintain better control of these and other health factors, you may reduce your risk for developing dementia.

In a 2008 paper in The Journal of the American Medical Association, Vladimir Hachinski, MD, FAAN, a professor of neurology at the University of Western Ontario, noted that 20 percent of people with stroke end up with dementia and two-thirds suffer other cognitive problems. "Treating vascular risk factors can prevent stroke and possibly delay the onset of dementia," he wrote.

So neurologists are focusing more on monitoring patients' overall health and working with patients to reduce their risk factors for these conditions, says Dr. Lyketsos. That also means encouraging good nutrition habits and regular physical and mental activity, which contribute to independence and quality of life.

Epilepsy

The emphasis on managing disease through lifestyle changes is also one of the biggest changes Orrin Devinsky, MD, FAAN, has observed during his 25 years of treating patients with epilepsy. "When I started, [doctors] focused on medicines," says Dr. Devinsky, director of the Comprehensive Epilepsy Center at New York University's Langone Medical Center.

Dietary changes were never used to control seizures, for instance. "Now I think there's a broader picture of the effect of lifestyle on epilepsy and an understanding that becoming seizure-free is not just about finding the right diagnosis, drug, and dosing, but also making sure people understand how important sleep, food, and avoiding excess alcohol are."

Another change is an understanding that quality of life for people with epilepsy encompasses not just controlling seizures and reducing the side effects of medications, but also identifying and treating depression, anxiety, and other mental health issues. "We've discovered that for people with persistent epilepsy, what most impairs their quality of life is not the seizure, but depression and anxiety," he says.

Dr. Devinsky points to another "truth" he learned during his training: the idea that seizures had no long-term effect on the brain. "Now we know that's wrong," he says. While an individual seizure isn't devastating, recurrent seizures over time contribute to cognitive impairment.

Migraine

Dr. Lipton says the past 30 years have been "a really exciting time for migraine," with huge areas of progress, thanks to advances in imaging techniques that enabled researchers to "see" what happens in the brain during a migraine.

"There was a time when we thought of migraine primarily as a pain disorder because the most prominent feature is head pain, so we tended to treat it only with pain relievers," Dr. Lipton recalls. Then they thought the pain of migraine came from dilated blood vessels, so doctors treated it with medications such as ergotamine that narrowed the blood vessels.

Today, however, migraine is recognized primarily as "a disorder of the brain and its interaction with blood vessels. We've also come to appreciate that it's not just an acute disorder where the prominent manifestation is the acute attack, but a chronic disorder with episodic attacks."

So even between attacks, he says, people with migraines have a "sensitive" brain, which means their nervous system is primed to overreact to triggers such as chocolate, red wine, or falling barometric pressure.

Given our current understanding, Dr. Lipton says, the disease is now treated with compounds such as triptans, which act directly on the nervous system, and with preventive medications designed to make the brain less excitable and reactive. There is also a greater focus on identifying and avoiding triggers.

Another change over the past two decades is the identification of the genes that contribute to migraine, particularly familial hemiplegic migraine, a form of migraine that runs in families. "We know those genes produce a state of brain hyperexcitability by raising levels of glutamate, a neurotransmitter or chemical in the brain that communicates information throughout the brain and body," he says. "Triptans act on the brain and the nerve endings in the brain to block the release of those neurotransmitters."

Recent trends in treating migraine include an increasing recognition that migraine is a constellation of diseases, not a single condition, Dr. Lipton says. He predicts that within 10 years, researchers will have defined several distinct disorders that make up migraines, which will enable more effective, targeted treatment.

Multiple Sclerosis

Barbara Giesser, MD, FAAN, a vice chair of neurology at the University of California, Los Angeles, remembers two myths she learned when she first began treating patients with MS: People with MS shouldn't exercise, and women with MS shouldn't have children. Both, she says, turned out to be wrong.

"Avoiding exercise is the single worst thing we could have told people," she says. "Exercise is good for people with MS for the same reason it benefits anyone—it provides cardiovascular conditioning and helps guard against comorbidities like obesity."

But exercise is particularly important for people with MS, she says. Studies have found it can improve fatigue, muscle strength, memory, and cognition. It has even been shown to protect neurons, at least in mice. "If you exercise mice, they get much less severe disease," she says. This may be due to the ability of exercise to increase certain growth factors and reduce certain inflammatory proteins.

As for pregnancy, Dr. Giesser says, "Not only do we now know that women with MS do better during pregnancy, but we're now trying a pregnancy-related hormone (estriol) as a treatment."

The entire approach to treating MS has also changed, she says. "When I started, we didn't have any disease-modifying agents, only drugs to treat patients during an acute attack." Today, however, the best approach is ongoing treatment with disease-modifying drugs coupled with other treatments for acute attacks. Plus, patients now begin treatment with the drugs as early as possible, overturning the initial thinking that they should be reserved as a final option.

The use of MRI has also revolutionized the ability of doctors to diagnose the disease and track its progression, Dr. Giesser says—including the current understanding that the disease can affect the brain even without visible signs of brain damage.

Dr. Giesser has also seen a change from the paternalistic approach of medicine to one in which patients are encouraged to become partners in their care. "Patients were used to being told what to do because that was the culture of medicine," she says. "Now we spend entire medical school classes teaching doctors how to engage patients in their care." This is particularly important in MS, she says, because patients now have so many choices for treatment—and there is no "best" option. "So we want our patients to be active partners and explore the options that would work best for them."

Parkinson's Disease

When Cheryl H. Waters, MD, FAAN, a professor of neurology at Columbia University Medical Center in New York City, began practicing 25 years ago, patients with PD were given a "doom-and-gloom" prognosis. Now, she says, "We recognize that Parkinson's is a chronic disease that isn't going away, but that you can live a valuable, quality life with it."

Dr. Waters has seen numerous other misconceptions about PD fall by the wayside, particularly the idea that PD is only a movement disorder. "We didn't recognize the other features we now know about," she says, such as depression, anxiety, apathy, sleep disorders, constipation, urinary changes, and erectile dysfunction. Yet these symptoms cause greater disability than the motor-related symptoms of PD.

One study of 1,072 people with PD, published in 2009 in the journal Movement Disorders, found that nearly all had at least one non-motor symptom. Drawing data from a claims database of nearly 24,000 people with PD, a 2011 study in the Journal of Parkinson's Disease found that 65 percent of PD patients developed some type of gastrointestinal disease in the four years after their diagnosis, compared with just one-third before their diagnosis. And a 2014 study published in the Journal of the Neurological Sciences found that people with pain and PD had significantly more non-motor symptoms than those without these conditions.

That's why a big part of Dr. Waters's practice involves managing non-motor symptoms to improve her patients' quality of life, often with medications.

Another change in the understanding of PD is the knowledge that the disease develops decades before the first symptoms appear. Early symptoms, such as loss of smell, chronic constipation, depression, and REM behavior disorder—in which a person acts out his or her dreams while sleeping—usually appear years before the first motor-related symptoms. This means that if we could find a neuroprotective drug, Dr. Waters says, we might be able to stop the disease in its earliest stages.

Finally, PD treatments—and the philosophy of when to start prescribing them—have changed, too. For instance, physicians used to wait as long as possible before treating with levodopa (also called L-dopa) because patients who take it eventually develop dyskinesias (involuntary movements). But now, she says, doctors believe there is no reason to wait.

The rapid pace of scientific and clinical discoveries in the field of neurology—and, indeed, throughout medicine—has significantly changed how neurologists treat most neurological diseases. This includes the ability to diagnose dementia earlier and to differentiate the various forms of the disease; a greater understanding of the frequency and impact of the non-motor symptoms of PD and the non-seizure aspects of epilepsy; and more targeted and effective treatments for migraine and MS.

"It's been a good 30 years for most of neurology," concludes Dr. Lipton.

Know the Basics

• Alzheimer's: The Basics 
• Epilepsy: The Basics 
• Migraine: The Basics 
• Multiple Sclerosis: The Basics 
• Parkinson's Disease: The Basics