Consumers of health care are increasingly sophisticated (especially you readers of Daily Health News!) and now pretty well-versed in the differing symptoms of related diseases — such as different types of cancer and different cardiovascular problems. Dementia, on the other hand, tends to be thought of as one problem that encompasses lots of symptoms involving forgetfulness and fuzzy thinking — but, in fact, it too takes many forms with distinct differences among them. Now scientists have just learned something important about one kind, called frontotemporal dementia(FTD), that accounts for somewhere between 2% and 10% of all dementia cases.
Like Alzheimer’s disease, frontotemporal dementia involves symptoms such as memory loss and cognitive decline, but the causes of the two types of dementia are different. And, I was told by Stephen M. Strittmatter, MD, PhD, the Vincent Coates Professor of Neurology at Yale School of Medicine, the more we understand about the differences between the two, the closer we come to finding treatments for them.
A Different Form of Dementia
While Alzheimer’s is characterized by the buildup of amyloid plaques in the brain, frontotemporal dementia is triggered by the degeneration of nerve cells in the frontal and temporal lobes, the areas involved with language, behavior and personality. Some individuals with this condition undergo personality changes (such as obnoxious or even obscene behavior, apathy, poor judgment) and act in socially inappropriate ways. Other important differences:Frontotemporal dementia is more likely to strike at a younger age — age 40 to 70 — than Alzheimer’s, and it also is characterized by a more rapid onset, specifically of difficulty using or understanding language. This contrasts with Alzheimer’s disease, where most patients experience a more subtle and gradual decline that typically affects only memory.
At Yale, Dr. Strittmatter and his colleagues are studying frontotemporal dementia at the molecular level in an attempt to understand what precipitates the degradation of those particular nerve cells. Previous research at other labs indicated that some forms of frontotemporal dementia are inherited, associated with a mutation in the gene for a protein called progranulin. Now, in lab and animal experiments, Dr. Strittmatter’s team has discovered that another protein called sortilinbinds or interacts with progranulin, causing a decrease in the amount of progranulin that can be absorbed by cells in the brain, possibly contributing to the development of frontotemporal dementia. Both progranulin and sortilin are found throughout the body and, while it is not known exactly how they function in the brain, it is believed that they help protect the health of neurons.
Dr. Strittmatter described these findings as the “first step” to understanding frontotemporal dementia, noting that they set the stage to begin working to find a therapeutic drug. “Eventually we hope to find a way to intervene in the disease and prevent or alleviate symptoms of this type of dementia,” he said.
Results of the study appeared in the November 18, 2010, issue of Neuron.
Use It or Lose It
Scientists have made significant progress over the last decade in distinguishing Alzheimer’s from other types of dementia, mainly by using positron emission tomography (PET) scans to detect amyloid plaques in the brain — but at present, there is no effective drug to prevent or treat dementia, whatever its basis. Researchers continue to explore the different causes of dementia so that treatments can be tailored to the different forms of the disease, which promises to be more effective than coming up with a one-size-fits-all therapy.
Meanwhile, for all of us, it is important to remain physically and intellectually active as we age. Use it or lose it, as they say. Keep walking or swimming, socializing with friends, visiting museums and playing challenging games such as chess or Scrabble. If you’d like to know more about frontotemporal dementia, you can find information from the Alzheimer’s Association at www.alz.org as well as from the more specialized Association of Frontotemporal Dementia (www.ftd-picks.org), where you can read about practical coping tips and join an online support group, message board or 24-hour helpline.
