Functional MRI brain imaging revealed that these symptomless carriers of the APOE-4 gene demonstrated significantly reduced functional brain connectivity between the hippocampus and the posterior cingulated cortex, two important brain structures for memory processing. These structures are relevant for information acquisition, filtering and sorting.

The study, conducted at Froedtert Hospital, was led by Shi Jiang Li, Ph.D., professor of biophysics, and was presented at the Alzheimer's Association International Conference on Alzheimer's disease in Chicago, July 29th

"Just as if cancer could be detected when there were only a few cells, decades before it was evident, the advantage of identifying those at great risk for having Alzheimer's would be of tremendous value in development of interventional therapies," says Dr. Li.

The researchers studied 28 neurologically-normal subjects, between ages 45 and 65. Twelve carried the APOE-4 gene and 16 did not. The two groups showed no significant difference in age, educational level, or neuropsychological performances. All subjects received fMRI scans. For each subject, functional connectivity between the two brain structures was measured in a resting state.

Results showed that functional connectivity in the non APOE-4 carriers was approximately 65 percent better than that of the carriers.

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Sleep is regulated by two processes: circadian and homeostatic. Circadian regulation affects the timing of sleep, and the homeostatic mechanism affects the need for sleep. The Sleepless gene affects the homeostatic mechanism.

Sleep isn't just for humans - it's been observed in everything from flies to dogs to people, indicating that it's essential to life. Insufficient and poor-quality sleep is an increasing problem in industrialized nations. In the U.S. alone, about 70 million people suffer from chronic sleep problems, which reduce workplace productivity, affect quality of life and can even be lethal.

"In the long term, we hope that human equivalents of our gene will be isolated and will not only further our understanding of human sleep, but perhaps also serve as drug targets to promote sleep or treat insomnia," says Sehgal.

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