Thin Brain Cortex May Be Early Sign Of Alzheimer’s
December 23, 2011

Thin Brain Cortex May Be Early Sign Of Alzheimer’s

According to a recent medical study, one indicator for the eventual onset of Alzheimer´s in elderly people may be a thinner cerebral cortex, the outer layer of the brain. As yet, however, researchers say this discovery can only be used to detect, not prevent, the development of the degenerative disease.

The study´s co-author, Dr. Brad Dickerson of Harvard Medical School, is nonetheless hopeful that the discovery will eventually be put to constructive use. He says that the find could play a key role in helping researchers track the progression of Alzheimer´s and thus test the efficacy of different medications.

The results of their study were published in Wednesday´s online issue of the medical journal Neurology.

Dickerson´s researchers examined the thickness of their patients´ cerebral cortexes, the outer sheet of neural tissue that encompasses the cerebrum of all mammalian brains. The cortex is critical for a number diverse brain functions, such as  memory, attention, perceptual awareness, thought, language, and consciousness.

According to Dickerson, scientists were looking for those areas of the brain that are “particularly vulnerable” to Alzheimer´s. “We´re looking at [“¦] parts that are important for memory, problem-solving skills and higher-language functions,” he explained to Randy Dotinga of USA Today's HealthDay.

Previous studies have found that different segments of the cerebral cortex were smaller in people suffering from Alzheimer´s-induced dementia.

“It´s like an orange that´s shriveling,” says Dickerson. “The thickness of the outer skin might get thinner as it dries out.”

His research team examined the MRI brain scans of 159 men and women with an average age of 76. After a three-year interval, subjects were asked to return to undergo various exercises testing their brain function.

Researchers found that the 15 percent of participants with the thinnest cortexes scored the worst on the tests. Of these, some 20 percent exhibited clear signs of cognitive decline. For patients in the middle range of cortex thickness, about 7 percent experienced degenerating cognitive abilities, while those with the thickest exhibited no signs cognitive decline at all.

Dickerson´s team also found that those patients with the thinnest outer layers of brain matter also showed increases in signs of abnormal spinal fluid, one potential sign of Alzheimer´s disease.

The cost of MRI scans has declined in recent years, and some believe that they may eventually become an standard tool for helping to predict Alzheimer´s. And because an increasing number of elderly patients are already getting scans for other reasons, checking for a thinning cortex could someday be tacked on to other diagnostic procedures.

Cathy Roe, an assistant professor of neurology and Alzheimer´s expert at the Washington University School of Medicine in St. Louis believes the recent findings could prove useful in the not-so-distant future when better medications are created for fighting the disease.

“Right now, there is not much we can do to delay the progression of dementia,“ Roe told Dotinga, “But once effective treatments are identified, this research could help to identify which patients should receive that treatment and when they should receive it.”

With no cure for the fatal disease on the immediate horizon, Dickerson agreed that the best way to put these findings to work is to use them to figure out which medications work and which don´t.

According to the Alzheimer´s Association, the degenerative mental disease is the sixth leading cause of death in the US, with the number of Alzheimer´s-related deaths rising annually.


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