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Study Confirms Insulin Spray Can Deliver Alzheimer's Drugs Directly to Brain
Last reviewed: 27.07.2025
A breakthrough brain-imaging study by Wake Forest University School of Medicine scientists has confirmed a key step toward new treatments for Alzheimer’s disease: Intranasal insulin, delivered through a simple nasal spray, safely and effectively reaches key memory areas of the brain in older adults. The study also found that people with early cognitive decline absorb insulin differently.
This study, published in the journal Alzheimer's & Dementia: Translational Research & Clinical Interventions, describes the results of an important experiment using positron emission tomography (PET) scanning.
It directly demonstrates that intranasal insulin penetrates 11 key brain regions associated with memory and cognitive function. Previously, scientists had problems with clinical trials of intranasal insulin because they could not confirm whether the drug was reaching the target brain regions.
“This study closes a critical gap in our understanding of how intranasal insulin gets to the brain,” said Suzanne Kraft, PhD, professor of geriatric medicine at Wake Forest University School of Medicine and director of the university’s Alzheimer’s Disease Research Center. Insulin resistance is a known risk factor for Alzheimer’s disease, Kraft said.
Key findings of the study
- Participants: 16 older adults (mean age 72 years), of whom 7 were cognitively normal and 9 had mild cognitive impairment (MCI).
- Method: Using a new radiomarker [68Ga]Ga-NOTA-insulin and a special system for six-time nasal sprays, a 40-minute PET scan of the brain was performed followed by whole-body imaging.
Results:
- Increased insulin uptake in brain regions critical for memory and cognitive function, including the hippocampus, olfactory cortex, amygdala, and temporal lobe.
- Cognitively normal individuals had higher absorption and different temporal patterns of insulin delivery compared to the MCI group, who had rapid initial absorption and more rapid elimination.
- In women, insulin absorption was strongly correlated with markers of cardiovascular health, and elevated levels of ptau217 (a marker of brain amyloid associated with Alzheimer's disease) were associated with reduced insulin absorption in several brain regions.
- Only two participants reported mild headache after scanning, which resolved within 24 hours, indicating that the procedure was well tolerated.
“One of the biggest challenges in developing brain drugs is delivering agents into the brain,” Kraft said. “This study shows that we can effectively validate intranasal delivery systems, which is an important step before launching therapeutic trials.”
Why is this important?
- In contrast to anti-amyloid drugs with limited efficacy and side effects, intranasal insulin delivery may offer an alternative metabolic approach to treatment.
- A new technique helps explain why some patients respond better to insulin therapy than others, opening the way to personalized treatment strategies.
The team is now planning larger studies over 12 to 18 months to examine the impact of vascular health, amyloid deposits and sex differences on insulin delivery to the brain.
"While there is still much to learn, these results show that we now have the tools to test drug delivery to the brain," Kraft said. "This is encouraging news for the development of more effective and affordable treatments for Alzheimer's disease."