- Posted July 24, 2025
Insulin Nasal Spray Reaches Alzheimer's Targets, Brain Scans Show
Insulin delivered by nasal spray might be a potential treatment for Alzheimer’s disease, a new study says.
An insulin nasal spray effectively reached key memory regions in the brains of a small group of older adults, researchers reported July 23 in the journal Alzheimer’s & Dementia: Translational Research & Clinical Interventions.
The hormone insulin is being considered as a potential therapy for Alzheimer’s, with the theory being that it could enhance brain activity. Insulin resistance is a known risk factor for Alzheimer’s, researchers noted.
But earlier efforts couldn’t confirm whether insulin delivered through the nose actually was reaching its brain targets, researchers said.
Scans in this new study revealed that intranasal insulin travels to 11 key brain regions associated with memory and cognition.
Researchers also found that people in early cognitive decline absorbed the insulin differently.
“This study fills a critical gap in our understanding of how intranasal insulin reaches the brain,” senior researcher Suzanne Craft, a professor of gerontology and geriatric medicine at Wake Forest University School of Medicine in Winston-Salem, N.C., said in a news release.
Researchers needed direct evidence that the drug is able to reach key brain targets.
"An unexpected finding was the observation that uptake may differ in people with early cognitive decline,” said Craft, who is also director of the Wake Forest Alzheimer’s Disease Research Center.
“This means we’re no longer flying blind; we now have a roadmap directly to the brain,” she said.
For the study, researchers performed brain scans on 16 seniors with an average age of 72, including seven who were cognitively normal and nine with mild cognitive impairment, after they’d taken intranasal insulin. The participants described the nasal spray as “surprisingly easy” to take.
The scans revealed elevated insulin uptake in critical memory and thinking areas like the hippocampus, amygdala, temporal lobe and olfactory cortex.
People with healthy brains also had higher uptake of the insulin compared to those with mild cognitive impairment, researchers found.
In women, those with healthy heart function tended to have better insulin uptake. On the other hand, those with elevated levels of a marker for amyloid beta had decreased absorption across multiple brain regions. High levels of amyloid beta indicate an increase risk for Alzheimer’s.
Only two participants reported mild headaches after the spray and scan, indicating the treatment is well-tolerated, researchers said.
“One of the biggest challenges in developing treatments for brain diseases is getting agents into the brain,” Craft said. “This study shows we can validate intranasal delivery systems effectively, an essential step before launching therapeutic trials.”
The findings also show why some patients might respond better to intranasal insulin than others, she said.
“There’s an urgent need to identify effective and feasible ways to prevent and treat Alzheimer’s dementia,” Craft said. “These findings show that we can now validate whether treatments are actually reaching their intended brain targets, which is critical information for designing successful trials.”
The Wake Forest team plans larger studies within the next one to two years to explore other factors that might influence brain insulin delivery, such as blood vessel health, amyloid beta plaques and sex differences.
“While there’s still a lot to learn, these findings show that we now have the tools to validate intranasal drug delivery to the brain,” Craft said. “This is promising news for developing more effective and accessible treatments for Alzheimer’s disease.”
More information
The Alzheimer’s Drug Discovery Foundation has more on intranasal insulin.
SOURCES: Wake Forest University, news release, July 22, 2025; Alzheimer’s & Dementia: Translational Research & Clinical Interventions, July/September 2025
