Using powerful new drug-screening technologies, researchers are
identifying dozens, perhaps hundreds of possible targets for drugs aimed at
preventing, treating, or slowing the progression of Alzheimer's disease (AD).
Many of these compounds appear to work in animals with Alzheimer's-type
dementia -- good news for little furry creatures.
But for the estimated 25 million people worldwide with
Alzheimer's disease and other forms of dementia and the millions more who care
for them, the news about drugs for Alzheimer's disease -- after the first blush
of enthusiasm has faded -- has ranged from mildly promising to
The symptoms of Alzheimer's disease often come on gradually. They then typically progress over several years to the point of causing major impairment.
Alzheimer's can be divided into mild, moderate, or severe stages. Each stage has a separate set of symptoms. But symptoms can vary from person to person. And the length of each stage can also vary.
Perhaps it's a measure of how difficult the problem is that one
of the biggest headlines from the 9th International Conference on Alzheimer's
Disease and Related Disorders in Philadelphia came from a clinical trial of the
drug Aricept. The drug appears to delay the onset of Alzheimer's disease in
people with mild cognitive impairment by six to perhaps 18 months, according to
researcher Ronald Petersen, MD, PhD, from the Mayo Clinic in Rochester, Minn.
Mild cognitive impairment appears to set the stage for the development of
There is no cure for Alzheimer's disease. The drugs used to
treat the disease work to slow the progression of symptoms. Aricept works by
preventing the breakdown of acetylcholine, a chemical used by the brain for
memory and thinking. But studies have shown that the benefits of this treatment
are short lived; by 18 months, patients who received Aricept had the same rate
of progression to Alzheimer's disease as those who received a placebo.
Aricept is one many drugs used to treat Alzheimer's disease. It
and medications such as Reminyl and Exelon are called cholinesterase
inhibitors. In various studies, these drugs have shown small to modest
improvements in memory and thinking skills in people with AD.
In April 2005, Reminyl's label
was changed to include information about the deaths of 13 elderly patients who
were taking the drug during a study. The deaths were due to various causes,
including heart attack and stroke.
Another group of drugs, called NMDA receptor antagonists, have
also shown minor improvements in mental function among patients with moderate
to severe AD. These drugs work by controlling the levels of another chemical
that is involved in processing and retrieving information.
Namenda is the only drug in this class approved for the
treatment of moderate to severe AD. A recently published study showed that
Namenda combined with Aricept allowed people with moderate to severe
Alzheimer's disease to perform better in daily activities such as grooming,
being left alone, and using the toilet. People receiving the drug combination
also had a reduction in behavioral disturbances such as agitation and
psychiatric symptoms that are among the most common causes of nursing-home
placements among patients with AD. Studies presented at the current meeting
also suggest that the drug is safe and effective at improving mental abilities
and daily functioning.