Researchers working on two early-phase studies of treatments for MCI and Alzheimer's disease reported promising results in 2011 and early 2012. These findings and other incremental discoveries may soon lead to major clinical trials that result in effective treatments for Alzheimer's disease. Even results from failed clinical trials ultimately prove useful, as they provide important insights into the disease and will inform future studies.
A small, preliminary trial showed that nicotine delivered via a skin patch alleviated some symptoms of MCI in nonsmoking older volunteers. The 6-month pilot study, led by researchers at the University of Vermont College of Medicine, Burlington, involved more than 70 participants; 39 received 15 mg of nicotine daily while 33 wore a placebo patch. Cognitive testing showed improvements in attention, memory, and mental processing in volunteers receiving nicotine compared to the placebo group (Newhouse et al., 2012). The nicotine patch was also shown to be safe. A larger study is needed to further examine this promising intervention.
The hormone insulin has several important functions in the brain, including regulating how glucose (sugar) is used by neurons. Alzheimer's disease disrupts insulin's normal function in the brain, and basic studies continue to examine the relationship between glucose and Alzheimer's. Scientists had enough evidence to see if regulating glucose might help treat Alzheimer's. In a pilot clinical trial led by researchers at the Veterans Affairs Puget Sound Health Care System, Seattle, insulin was delivered via a nasal spray to more than 100 study volunteers with either MCI or mild to moderate Alzheimer's disease (Craft et al., 2012).
The novel delivery system enabled the insulin to easily bypass the blood-brain barrier and enter the brain but did not have unwanted side effects elsewhere in the body. Researchers found that the lower of two tested doses improved memory, and that both the lower and higher doses staved off decline in general cognition and functional abilities after 4 months. In preliminary analyses, changes in memory and function were accompanied by changes in CSF levels of Alzheimer's biomarkers.
Based on these promising results, in early 2012 as part of the President's Alzheimer's Disease initiative, NIH Director Francis Collins provided funds to jump-start further testing of the intranasal insulin therapy.