Insulin detemir could offer a promising new treatment for patients with Alzheimer's or MCI, according to the study.
The researchers, led by Suzanne Craft, PhD, professor of gerontology and geriatric medicine at Wake Forest, found the spray may also be effective for patients with mild cognitive impairment (MCI), which is estimated to affect around 10-20% of people over the age of 65.
In September 2011, Medical News Today reported on another study by Craft and colleagues revealing that an insulin nasal spray improved memory among patients with Alzheimer's and other forms of cognitive impairment.
In that study, participants received 20 or 40 international units (IU) of insulin via a nasal drug delivery device. In this latest study, however, the team used the same device to deliver 20 or 40 IU of insulin detemir - a manufactured form of insulin that provides longer-lasting effects, compared with "regular" insulin.
Working memory improved for patients with MCI, Alzheimer's
Each day for 21 days, 60 adults who had been diagnosed with MCI or mild to moderate Alzheimer's disease received either 20 IU of a placebo, or 20 or 40 IU of insulin detemir - all of which were administered nasally.
The study findings - published in the Journal of Alzheimer's Disease - revealed that participants who received 40 IU of insulin detemir showed major improvement in their working memory - the ability to retain and process new information - compared with participants who received 20 IU of insulin detemir or the placebo.
What is more, participants who received 40 IU of insulin detemir and who possessed APOE-e4 - a gene associated with increased risk of Alzheimer's - displayed higher scores on memory tests than participants who received the lower insulin detemir dose or the placebo.
Participants who did not have the APOE-e4 gene had lower memory scores, regardless of whether they received a 20 or 40 IU dose of insulin detemir or the placebo.
On assessing the safety of the insulin detemir spray among participants, they found it only triggered minor side effects.
Commenting on their findings, Craft says:
"The study provides preliminary evidence that insulin detemir can provide effective treatment for people diagnosed with MCI and Alzheimer's-related dementia, similar to our previous work with regular insulin.
We are also especially encouraged that we were able to improve memory for adults with MCI who have the APOE-e4 gene, as these patients are notoriously resistant to other therapies and interventions."
The team says further research is needed to investigate the mechanisms that underly the association between insulin detemir administration and improved memory among people with the APOE-e4 gene.
In addition, Craft says future studies should further assess the "safety and efficacy of this promising treatment."
Last month, MNT reported on a study published in the journal eLife, in which researchers claim to have discovered a way to restore lost memories for patients in the early stages of Alzheimer's.
Senior author David Glanzman, of the University of California-Los Angeles, and colleagues explain that this could be done by encouraging the nervous system to regenerate damaged connections between brain cells.