Suggests Similar Cause of Symptoms, Whether They Begin Early or Late in Life

Although we have long suspected genetic causes for Alzheimer's disease, progress in isolating all the possible genetic causes is slow. Now, three separate research groups have uncovered a new genetic link to Alzheimer's disease.

Alzheimer's disease is the most common cause of dementia, which refers to any and all medical conditions, usually occurring in old age, that lead to deterioration of the mental capacity of the brain, resulting in symptoms that include memory loss, disorientation, and confusion.

But Alzheimer's disease can occur much earlier in life, too, striking people in their 40s or 50s. It is this type of the disease, which is referred to as early onset Alzheimer's, that has been understood to have a strong genetic basis, meaning that it can be inherited from family members.

More recently, investigators have found that late onset Alzheimer's disease, which usually strikes after age 60, also has some genetic basis. It is vitally important to uncover what genes are involved in late-onset Alzheimer's because this makes up 90-95% of cases of this devastating condition, and understanding what genes are involved can help direct research on new treatments or prevention strategies.

"We have another clue added to the few we already have about what might cause late onset Alzheimer's disease," D. Stephen Snyder, PhD, tells WebMD during an interview seeking an objective assessment of the three recently published studies. "This is sifting through about 100,000 [possible] genes ... [to find ones] that may be responsible for late onset Alzheimer's disease, which is by far the most predominant form of the disease." Snyder is project director of the etiology of Alzheimer's disease at the National Institute on Aging (NIA), which is part of the National Institutes of Heath (NIH).

He explains that if these genes ultimately turn out to be the ones that cause the manufacture of proteins that are involved in the production of amyloid, which is believed to be the main culprit causing the brain damage in Alzheimer's disease, then we may be able to come up with therapies to treat the problem in the near future.

In the studies published in the Dec. 22, 2000 issue of the journal Science, the researchers all identified an area in or around a part of the gene referred to as chromosome 10. Strangely, the discovery of the genetic link was achieved by different means in all the studies.

Co-authors of two of the studies, Alison Goate, PhD, and Steven Younkin, MD, PhD, speculate that this research could have several clinical implications, if the specific genes on chromosome 10 involved in Alzheimer's disease are identified and confirmed. For instance, they could be a target for new therapies, help to identify those at high risk for developing Alzheimer's disease, or help identify those individuals most likely to benefit from Alzheimer's disease therapies.

These studies received support from the National Institutes of Health via the National Institute of Aging and the National Institute of Mental Health (NIMH).

(From Excite.com)