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Individuals who have Alzheimer's disease in their family line have a much higher risk than the general population does for developing the disease. The highest statistic is for someone who has a parent or sibling diagnosed with Alzheimer's, raising their risk approximately 3.5 times as likely to get it. With each additional relative, this risk will increase. All of this is caused by mutations in specific genes, with several genes associated with early onset Alzheimer's disease—with only "one" mutated copy of the gene necessary to inherit to develop the disease. Unfortunately, those with inherited mutated gene forms will develop Alzheimer's under the age of 65.

There are three genes which play a big role in Alzheimer's disease. In fact, about 5% of all the disease is actually caused by a mutation in one of the three genes: PS2/presenilin 2; APP; and PS1/presenilin, with each gene inherited in a dominant fashion. The term "dominant fashion" refers to the fact it is necessary to inherit only one copy of a particular gene in order to develop Alzheimer's.

PS1 GENE

The Psi gene mutations account for about half of all early onset Alzheimer's diseases. Unfortunately, little is known about PS1, which contains more than 40 different mutations. With PS1 causing the most severe onset of Alzheimer's from age 29 to 62 (averaging 44 years of age), families tend to develop the disease at the same age. Also, those with this gene have a weakness in the legs and more extensive brain changes than those without it.

PS2 GENE

Similar to the PS1 gene, little is known about it as mutations in the PS2 gene are rare. What has been found is that the gene's mutations have been found in only six different families with Alzheimer's disease—five German families and one Italian family. What has been found is that mutations in PS2 actually will cause less aggressive forms of Alzheimer's disease than those with PS2 mutations. Also, people with PS2 mutation have more of an age variance in the same family who develop Alzheimer's disease symptoms.

RESEARCH INTO RISK-FACTOR GENES IN ALZHEIMER'S DEVELOPMENT

Vitally important in the research for Alzheimer's disease is the determination how its risk-factor genes may interact with other genes or factors such as lifestyle or environment. Also, researchers are helping to identify people who are at high risk in order for early Alzheimer treatment—with a focus on new preventions or treatment approaches. To answer questions such as these, the National Institution on Aging (NIA) is launching the Alzheimer's Disease Genetics Study and the Alzheimer's Disease Genetics Consortium. These studies will collect and analyze blood samples along with biological information from families on a global basis with and without the late-onset of Alzheimer's disease.

"AGING WITH GRACE"

A unique Alzheimer's disease research project covering a span of 20 years has involved nuns aged 90 and older. In 1986, a religious nun school called the "Sisters of Notre Dame" had made headlines with their insights regarding the lifestyle and personality traits of people who were at risk of dementia. Originally, more than 600 elderly nuns had volunteered to let Dr. David Snowdon, a former University of Minnesota scientists, study them for clues on how aging affecting the brain. Today, only 52 of the original volunteer nuns are alive which include 6 retired Mankato nuns age 93-102.

All 600 of the nuns had agreed to donate their brains to science, considered an ideal study group due to a common diet, lifestyle, and backgrounds. Studying which ones developed dementia the risk factors could be brought into play, with half the nuns developing some form of dementia by the time they died. Of a dozen who had no signs or symptoms of dementia when alive, were found to have Alzheimer's disease in the brain tissue after death.