Protein linked to ALS and dementia

October 13, 2006|By Tom Avril | Tom Avril,MCCLATCHEY-TRIBUNE

Doctors have known for years that some people with Lou Gehrig's disease also suffer from a type of dementia. And some with that dementia also develop crippling symptoms such as Lou Gehrig's, gradually losing control of their muscles.

Today, a team led by University of Pennsylvania scientists reports the discovery of a likely culprit in both. The two distinct diseases are marked by an abnormal accumulation of the same protein - a startling two-for-one discovery described in the journal Science.

"It's huge," said Mike Hutton, a neuroscientist at the Mayo Clinic College of Medicine in Jacksonville, Fla., who was not involved with the study. "It completely changes the way in which I think ALS [amyotrophic lateral sclerosis] research will focus," he added.

With this find, science has identified at least one faulty protein associated with each of the major neurodegenerative diseases - Alzheimer's, Parkinson's and Huntington's, among others. Cures remain years away, but pinpointing the apparent culprit is a major step toward fighting it.

The dementia in the new research is a type of frontotemporal dementia, marked by toxic clumps of proteins in the brain's frontal and temporal lobes, which control judgment and behavior. It is less common than Alzheimer's and tends to strike younger people.

It is unclear how many thousands of people have it. That's partly because it can lead to criminal or sexually deviant behavior, and some people may never come to the attention of doctors because they are in prison.

ALS is diagnosed in 5,600 people in the United States every year, and up to 30,000 have it at any given time, according to the nonprofit ALS Association. It is almost always fatal.

Scientists aren't certain whether the protein accumulations described in Science directly cause either disease or merely play a supporting role. But they say they are part of a cascade of events that leads to disease.

The team worked with diseased tissue from several brains donated by deceased dementia patients.

The culprit: a previously known protein called TDP-43.

TDP-43 is normally present in the nuclei of healthy brain cells, and is believed to play a role in transcribing the genetic code. In sick patients, however, it shows up as clumps in unusual places: usually outside the nucleus but sometimes in an odd, lens-shaped clump inside.

The researchers found TDP-43 clumps in all 53 brains with frontotemporal dementia they examined.

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