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ALZHEIMER DISEASE (AD) is the fourth leading cause of death in adults. The incidence of the disease rises steeply with age.
AD is twice as common in women than in men, although ex-president Ronald Reagan is a well known disease sufferer. Some of the most frequently observed symptoms of
the disease include a progressive inability to remember facts and events
and, later, to recognize friends and family.
AD tends to run in families: currently, mutations in four genes, situated on chromosomes 1, 14, 19 and 21, are believed to play a role in the
disease. The best-characterized of these are PS1 (or AD3) on chromosome 14 and PS2 (or AD4) on chromosome 1. The formation of lesions made of fragmented brain cells
surrounded by amyloid-family proteins are characteristic of the disease.
Interestingly, these lesions and their associated proteins are closely
related to similar structures found in Down's Syndrome. Tangles of
filaments largely made up of a protein associated with the cytoskeleton
have also been observed in samples taken from Alzheimer brain tissue.
Currently, scientists are studying the interrelationship between the various gene loci (particularly the mutation on chromosome 21), and how
environmental factors could effect a person's susceptibility to AD.
Recently, use of a mouse model of the disease identified an enzyme that
may be responsible for the increase in amyloid production characteristic
of AD. If a way to regulate this enzyme could be found, then AD may be
slowed or halted in some people.