People with a sleep disorder that causes them to kick or cry out during their sleep may be at greater risk of developing dementia or Parkinson’s disease, according to a study published in the December 24, 2008, online issue of Neurology®, the medical journal of the American Academy of Neurology.

The sleep disorder is called REM sleep behavior disorder. People with the disorder do not have the normal lack of muscle tone that occurs during REM sleep, often known as the dream stage of sleep. Instead, they have excessive muscle activity such as punching, kicking, or crying out, essentially acting out their dreams.

The study involved 93 people with this type of sleep disorder who had no signs of a neurodegenerative disease, such as dementia or Parkinson’s disease. The participants were followed for an average of five years. During that time, 26 of the people developed a neurodegenerative disease. Fourteen developed Parkinson’s disease, 11 developed dementia and were diagnosed with either Alzheimer’s disease or Lewy body dementia. One person developed multiple system atrophy, a rare disorder that affects movement, blood pressure and other body functions.

The estimated five-year risk of developing a neurodegenerative disease was 18 percent, with the 10-year risk at 41 percent and the 12-year risk at 52 percent.

“These results are obviously of great interest to people who have this sleep disorder and their physicians and families,” said study author Ronald B. Postuma, MD of McGill University in Montreal, Canada, who carried out the studies at the sleep disorders center at the Sacre Coeur hospital, University of Montreal. Postuma is also a member of the American Academy of Neurology. “The results may help us better understand how these neurodegenerative diseases develop. They also suggest that there may be an opportunity for protecting against the progression to disease, perhaps even preventing it before the symptoms can appear.”

Postuma noted that the study involved only people with no known cause for the REM sleep behavior disorder. The disorder can also be caused by narcolepsy or rare brainstem abnormalities. REM sleep disorder from these causes does not necessarily carry the risk of developing a neurodegenerative disease, he said.

The study was supported by grants from the Canadian Institutes of Health Research and the FRSQ (Fonds de la recherché en santé du Quebec) in Montreal, Canada.

This article is brought to you by The American Academy of Neurology.

The study, reported earlier this month in the journal Neurology, adds to a growing body of evidence indicating MRI brain scans provide valuable diagnostic information about Alzheimer’s disease. The findings are important in light of many new disease-modifying drugs in trials — treatments that may prevent mild memory loss from advancing to full-blown dementia if administered early enough.

“We advocate, based on these findings, that the criteria for the diagnosis of Alzheimer’s disease should include MRI scans,” said the study’s lead author Ranjan Duara, MD, medical director of the Wien Center for Alzheimer’s Disease and Memory Disorders at Mount Sinai Medical Center who is affiliated with the University of Miami Miller School of Medicine and University of South Florida College of Medicine. “By incorporating MRIs into the assessment of patients with memory problems, early diagnosis can be standardized and done far more accurately.”

“This study demonstrates that MRI brain scans are accurate enough to be clinically useful, both in diagnosing Alzheimer’s disease itself at an early stage and in identifying people at risk of developing Alzheimer’s,” said Florida ADRC Center Director Huntington Potter, PhD, a neuroscientist at the Byrd Alzheimer’s Center and Research Institute, University of South Florida.

Alzheimer’s disease, the most common cause of dementia, is characterized by memory loss, disorientation, difficulty with reasoning and the decline of language and thinking skills. Alzheimer’s is diagnosed by a process of elimination since many other diseases and related disorders can mimic its symptoms, and autopsy is currently the only definitive way a diagnosis can be confirmed. The diagnosis often includes a medical history, mental status tests, neurological evaluations and blood tests. Physicians typically use brain scans only to exclude conditions that can also cause memory deficits, such as strokes and brain tumors.

The Florida researchers used a new visual rating system to evaluate the severity of shrinkage, or atrophy, in the brain’s medial temporal lobe – specifically in three structures essential for the conscious memory of facts and events. They compared the MRI brain scans of 260 people – a group with probable Alzheimer’s disease, two groups with varying degrees of mild cognitive impairment (mild memory problems), and a control group of normal elderly with no discernable memory loss. They found that scores generated by this MRI-facilitated test accurately distinguished each group from the other and correlated with the types of memory problems most frequently caused by Alzheimer’s disease. The more extensive the brain atrophy, the more advanced the clinical stage of Alzheimer’s disease.

The researchers even found brain atrophy in some people without memory complaints at the study’s onset who demonstrated memory decline when assessed a year or two later. This suggests MRIs could predict who will get the disease well before signs of dementia become apparent by other diagnostic methods as well as rule out an Alzheimer’s diagnosis in people experiencing memory problems, Dr. Duara said. “If you don’t have changes in these three particular areas of the brain, then you don’t have Alzheimer’s.”

Researchers at centers like Miami’s Wien Center and USF’s Byrd Institute are developing new Alzheimer’s drugs that attack mechanisms leading to the death of nerve cells and their connections. The emergence of these disease-modifying treatments has made an earlier diagnosis of Alzheimer’s increasingly important, Dr. Duara said. “Having an accurate diagnosis will allow us to start using drugs earlier. The earlier treatment begins, the more likely you are to stop disease progression and benefit the patient.”

Most participants in the MRI study were enrolled in the clinical arm of the Florida ADRC, which is supported by a grant from the National Institute on Aging.

The Florida ADRC, the first statewide, multi-center ADRC in the United States, was critical for the successful implementation of the study, said Dr. Potter, the study’s senior author. “To validate any new diagnostic test or treatment, you need a large number of diverse volunteers for good comparisons. Alzheimer’s research is a partnership between the scientific community and study volunteers; we need both to solve the complexities of Alzheimer’s disease.”

USF Health is dedicated to creating a model of health care based on understanding the full spectrum of health. It includes the University of South Florida’s colleges of medicine, nursing, and public health; the schools of biomedical sciences as well as physical therapy & rehabilitation sciences; and the USF Physicians Group. With $360 million in research funding last year, USF is one of the nation’s top 63 public research universities and one of Florida’s top three research universities.

This article is brought to you by Anne DeLotto Baier, University of South Florida Health.