Is Very Late Onset Alzheimer Disease Influenced by Genetics?

The incidence of Alzheimer Disease reaches the highest levels after 85 years of age. Although genetic factors are believed to be involved in Alzheimer Disease with substantially earlier onset, the family characteristics of high-incidence very late-onset Alzheimer disease (Very Late Onset Alzheimer Disease, defined here as Alzheimer Disease with onset age > or= to 85 years) remain a question. Does Very Late Onset Alzheimer Disease have a strong genetic component?

We predict or propose that as a person rises in age, the genetic factors may become less of a cause alone, and that there may be other factors that become involved, such as environmental ones.

We collected information about the thinking and intellectual or cognitive status and demographics of 809 parents and siblings of 144 Very Late Onset Alzheimer Disorder subjects, 4235 parents and siblings of 793 earlier-onset Alzheimer Disease subjects, and 7646 parents and siblings of 1493 elderly subjects with no signs of Alzheimer Disease. Growing risks and 5-year hazard rate ratios were calculated for Alzheimer Disease in relatives of the 2 Alzheimer Disease subject groups and relatives of the elderly group who do not have Alzheimer Disease.

The cumulative risk for Alzheimer Disease in the relatives of Very Late Onset AlzheimerDisorder subjects was significantly different than that in the relatives of earlier-onset Alzheimer Disease subjects (P_.001), but not in the relatives of elderly subjects who do not have Alzheimer Disease. Also, the relatives of earlier-onset Alzheimer Disease subjects had hazard rate ratios ranging from 19.7 in those aged 50 to 54 years to 1.2 in those aged 90 to 94 years. Rates successively dropped as age intervals increased.

At least through the middle of the nineties (in terms of age), relatives of Very Late Onset Alzheimer Disorder subjects have a lower risk for Alzheimer Disease than those of earlier-onset Alzheimer Disease subjects. In addition, the relatively increased risk of relatives of earlier onset Alzheimer Disease subjects is highest at younger ages and lessens with  increasing age. In counseling family members of patients with Alzheimer Disease concerned about their own risk, the onset age of the patient and the age of the concerned relative should be considered. Very late-onset Alzheimer Disease may be a good target for investigating environmental factors associated with Alzheimer Disease.

1. What research question or problem was (were) the researcher(s) interested in studying.
2. The possible hypothesis or prediction of the results (you may have to read between the lines for this one).
3. The method of gathering data that was used by the researcher(s)
4. How they went about analyzing or processing the data or information gathered
5. What conclusions did the researcher(s) come to