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Scientists explore sits at the center of this dementia and brain health question.
Scientists have discovered a promising new pathway to deliver Alzheimer’s treatment directly to the brain through the nasal passages—a region remarkably close to critical memory centers. Recent research, particularly a 2025 study from Wake Forest Baptist, has validated that intranasal delivery of insulin reaches 11 key brain regions associated with memory and cognition, offering a potential breakthrough for patients who struggle with traditional pills and injections. This method bypasses the digestive system entirely, allowing medication to travel directly through the cribriform plate—the thin bone separating the nasal cavity from the brain—and into cerebrospinal fluid, where it can reach damaged neural tissue. The significance of this approach lies not just in its directness, but in its effectiveness.
While the brain is notoriously difficult to access due to the blood-brain barrier that blocks most medications, intranasal delivery provides a natural biological shortcut that evolution has already engineered. Drugs can travel via the olfactory pathway through smell-sensing neurons or via the trigeminal nerve that runs through facial and eye regions. For Alzheimer’s patients, this means medication can arrive where it’s needed—in memory centers like the hippocampus—without the time delay and reduced effectiveness of oral medications. A Phase 2 clinical trial launched in May 2025 is now testing whether this approach works reliably in real-world conditions. The trial, using an Aptar Pharma CPS intranasal device, will follow adults with preclinical Alzheimer’s disease through May 2029, determining whether this delivery method can become a standard treatment option.
Table of Contents
- How Does Intranasal Delivery Reach the Brain Near the Eyes?
- What Makes Intranasal Delivery Different for Alzheimer’s Patients?
- What Does the Wake Forest Research Actually Show?
- What’s the Timeline for Intranasal Alzheimer’s Treatment?
- What Are the Remaining Questions and Challenges?
- How Does This Compare to Current Alzheimer’s Treatment Options?
- What Comes Next for Brain-Targeted Drug Delivery?
- Conclusion
How Does Intranasal Delivery Reach the Brain Near the Eyes?
The pathway from your nose to your brain is surprisingly direct—much more so than medications traveling through your bloodstream. When insulin or other Alzheimer’s medications are delivered as a nasal spray, they dissolve in the mucous membranes lining your nasal cavity and take two main routes. The first is through the olfactory pathway: tiny molecules cross the epithelium, enter olfactory neurons (your smell-sensing cells), and travel directly along those nerves into the olfactory bulb at the base of your brain. The second is through the trigeminal nerve, which has branches extending into the eye region (the ophthalmic branch) and the upper jaw (the maxillary branch), creating additional entry points near crucial brain structures. This is fundamentally different from eye drops, which cannot cross into the brain effectively because the eye’s natural drainage systems redirect them away from neural tissue.
Instead, the nasal cavity functions as a gateway with direct neural highways. The cribriform plate—that thin bone with tiny holes that separates your nasal passages from your brain—acts like a biological checkpoint where medications can transition from the nose directly into the cerebrospinal fluid surrounding your brain. Once there, medications distribute throughout the brain much more efficiently than if they had to navigate the blood-brain barrier. The Wake Forest 2025 study mapped exactly where intranasal insulin reaches, confirming it successfully arrives in 11 memory-critical regions including the hippocampus, prefrontal cortex, and temporal lobes. This is particularly important because Alzheimer’s disease damages these regions first, causing memory loss and cognitive decline. By delivering medication directly where damage occurs, researchers bypass the inefficiency of systemic delivery where much of the medication gets metabolized before reaching the brain.
What Makes Intranasal Delivery Different for Alzheimer’s Patients?
One critical finding from recent research is that intranasal insulin absorption varies significantly between cognitively normal older adults and those with early cognitive decline. The Wake Forest researchers discovered that people showing early signs of cognitive impairment—those with mild cognitive impairment or preclinical Alzheimer’s—absorb and distribute intranasal insulin differently than healthy peers. This difference suggests the disease itself may alter how medications travel through the brain, a limitation that researchers must account for when designing treatment protocols and dosages. The advantage of intranasal delivery for Alzheimer’s patients extends beyond just reaching the right location. Many Alzheimer’s patients have difficulty swallowing pills, a condition called dysphagia that becomes increasingly common as the disease progresses. Some patients also have poor medication compliance because they forget to take daily pills—a particular problem when the disease affects memory and executive function.
An intranasal spray, used once or twice daily with simple instructions, potentially addresses both issues. However, there’s a significant limitation: patients must maintain adequate nasal function and mucosal health for the treatment to work effectively. Chronic nasal congestion, allergies, or upper respiratory infections could interfere with delivery. Additionally, while intranasal delivery avoids digestive system complications that plague many Alzheimer’s medications, it introduces its own potential issues. Some patients experience nasal irritation, congestion, or altered sense of smell from regular sprays. The dose must be calibrated carefully because the nasal cavity has limited absorptive surface area compared to the entire digestive tract. Too little medication doesn’t reach the brain effectively; too much may cause local irritation without additional benefit.
What Does the Wake Forest Research Actually Show?
The 2025 Wake Forest Baptist study used PET imaging—a brain scanning technology that shows exactly where radioactively-labeled insulin travels—to map the distribution of intranasal insulin in the aging brain. Researchers tracked insulin labeled with a radioactive tracer as it moved through the brain, documenting which regions accumulated the medication and in what concentrations. The results showed that intranasal delivery successfully reached all 11 measured regions associated with memory and cognitive function, including areas typically damaged earliest in Alzheimer’s disease. What made this study particularly valuable is that it provided the first human evidence that intranasal delivery could reach the brain in sufficient quantities to be therapeutically meaningful. Previous studies in animals showed promise, but human brains are more complex, with different blood flow patterns and barrier systems.
The fact that researchers could visualize insulin actually arriving in damaged brain regions—not just in general circulation—validated the entire approach. The study also confirmed that the medication traveled through the expected pathways: the olfactory bulb, cerebrospinal fluid, and distributed throughout neural tissue. The research distinguished between two groups of participants, which revealed an important nuance: older adults with early cognitive impairment showed different insulin absorption and distribution patterns compared to cognitively normal older adults. This suggests that Alzheimer’s disease may alter the anatomy or physiology of the nasal passages and brain’s uptake mechanisms, meaning future treatments may need personalized dosing based on a patient’s cognitive status. It’s a reminder that even promising delivery methods must be tested across different patient populations before becoming standard treatment.
What’s the Timeline for Intranasal Alzheimer’s Treatment?
The field has moved rapidly from laboratory validation to human testing. The upcoming Phase 2 clinical trial, launched in May 2025, represents the next critical step. This trial differs from earlier studies because it tests a specific delivery device—the Aptar Pharma CPS (Controlled Particle Spray) intranasal system—to determine whether it can reliably and consistently deliver insulin to people with preclinical Alzheimer’s disease. The trial is scheduled to conclude in May 2029, meaning results won’t be available for several years, but patients and caregivers can already participate if they meet eligibility criteria. The timeline reflects careful, methodical research. Phase 2 trials typically involve 100-500 participants and focus on whether the treatment works and at what dose.
If results are positive, Phase 3 trials would follow, involving thousands of patients and comparing the intranasal approach to current standard treatments or placebos. Even with successful results, regulatory approval and insurance coverage typically take another 1-2 years. Realistically, intranasal Alzheimer’s medication may not be widely available until 2030 or later, though earlier access might be possible through compassionate use programs for patients who have few other options. Currently, there’s a major gap between what the science suggests is possible and what patients can actually access. Intranasal insulin for Alzheimer’s remains experimental; it’s not yet approved by the FDA as a standard treatment and is only available through clinical trials. This contrasts with existing Alzheimer’s medications like aducanumab or lecanemab, which are FDA-approved but work differently and have different effectiveness profiles. Patients interested in participating in intranasal trials should speak with their neurologist about enrollment opportunities.
What Are the Remaining Questions and Challenges?
Despite promising results, significant questions remain unanswered about intranasal Alzheimer’s treatment. Researchers still don’t fully understand whether insulin itself is the active ingredient slowing cognitive decline, or whether the delivery mechanism simply works better with other compounds. The Wake Forest study showed insulin reaches the right brain regions, but that’s different from proving it halts neurodegeneration or improves cognition in living patients—that evidence will come from the Phase 2 and Phase 3 trials. Additionally, insulin is a hormone with metabolic effects throughout the body; intranasal delivery may reduce systemic effects compared to injections, but long-term safety in Alzheimer’s patients remains to be established. Another limitation is that intranasal delivery works best for small molecules and proteins like insulin, but many experimental Alzheimer’s treatments are large antibodies or complex compounds that don’t absorb well through nasal tissue. Researchers continue developing new formulations and absorption-enhancing agents, but not every potential Alzheimer’s drug can use this pathway effectively.
There’s also the practical question of patient compliance: while nasal sprays seem simple, some patients struggle with consistent use, especially as cognitive decline worsens and executive function deteriorates. A caregiver’s involvement may be necessary, which isn’t always available. Safety monitoring is another ongoing concern. Long-term intranasal medication use could potentially affect the olfactory bulb or cribriform plate, though animal studies haven’t shown this. The nasal passages’ immune defenses might be overwhelmed by repeated daily exposure to pharmaceutical formulations. These questions highlight why careful clinical trial monitoring is essential—intranasal delivery to the brain is new enough that long-term safety data simply doesn’t exist yet.
How Does This Compare to Current Alzheimer’s Treatment Options?
Current FDA-approved Alzheimer’s medications like lecanemab (Leqembi) work by targeting amyloid protein buildup in the brain, which is believed to contribute to Alzheimer’s pathology. However, lecanemab requires intravenous infusion every two weeks, an inconvenience for patients and caregivers. Other medications like donepezil or memantine aim to preserve remaining cognitive function but don’t address underlying disease mechanisms. Intranasal insulin, by contrast, may work through metabolic pathways that support brain cell energy production and reduce inflammation—a different mechanism entirely.
The practical advantages of intranasal delivery are immediately apparent: daily spray versus bi-weekly infusions or daily pills that may cause gastrointestinal side effects. For patients with swallowing difficulties or memory problems affecting medication compliance, a simple twice-daily nasal spray offers real convenience. However, intranasal treatment isn’t inherently superior to other approaches—it’s simply different. The question of whether intranasal insulin actually works better than lecanemab or other approved treatments will only be answered once trials compare them directly, something that hasn’t yet been done.
What Comes Next for Brain-Targeted Drug Delivery?
The success of intranasal delivery pathways has opened researchers’ eyes to similar routes for other difficult-to-treat brain conditions. Parkinson’s disease researchers are exploring intranasal levodopa delivery. Migraine researchers are testing intranasal CGRP inhibitors. Neuropsychiatric conditions from depression to schizophrenia may eventually benefit from brain-targeted nasal delivery.
The nose, once overlooked as a drug delivery route, is now recognized as offering a direct highway to the brain that bypasses both the digestive system and the blood-brain barrier. Looking forward, the real breakthrough may come from combining intranasal delivery with personalized medicine. If genetic testing could identify which Alzheimer’s patients would benefit most from insulin versus other compounds, doctors could match the right intranasal medication to the right patient. The Wake Forest finding that cognitive decline alters insulin absorption suggests that future treatments will need to account for disease stage, genetic factors, and individual differences. By 2030, intranasal delivery may be as routine for neurological conditions as inhalers are for asthma—a simple, direct way to get medication to the tissue that needs it most.
Conclusion
Scientists have identified a promising new pathway for delivering Alzheimer’s treatment directly to the brain through nasal passages, bypassing both the digestive system and the blood-brain barrier. The 2025 Wake Forest study confirmed that intranasal insulin successfully reaches 11 key memory regions, and an ongoing Phase 2 clinical trial will determine whether this approach can actually slow cognitive decline. This method offers practical advantages for patients who struggle with pills or injections, while opening a new frontier in brain-targeted drug delivery.
However, intranasal treatment remains experimental and several years away from widespread availability. Patients interested in participating in clinical trials should discuss this option with their neurologist, and those currently diagnosed with Alzheimer’s should continue working with their care team on proven treatments while staying informed about emerging options. The next few years of research will determine whether this new delivery route becomes a standard part of Alzheimer’s care or a promising avenue that didn’t ultimately deliver the hoped-for clinical benefits.
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For more, see NIH MedlinePlus — dementia.
