Two doses of a nasal spray reduced chronic brain inflammation in aging mice and improved memory performance for several months. Dr. Ashok Shetty of Texas A&M University published the results in April 2026 in the Journal of Extracellular Vesicles. The active ingredient: tiny vesicles from human nerve stem cells that reach the brain directly through the nasal mucosa. Several development steps remain before human clinical trials, but the biological mechanism is reproducibly measurable.
What Is Neuroinflammation?
With advancing age, the brain's immune cells, called microglia, enter a permanently activated inflammatory state. The consequence is a smoldering chronic inflammation that damages nerve cells and slowly erodes cognitive functions. Researchers call this process neuroinflammaging. The study worked with 18-month-old mice, roughly equivalent to the biological age of a 60-year-old human. In these animals, two central inflammatory pathways were measurably overactivated: the NLRP3 inflammasome and the cGAS-STING signaling pathway, both known drivers of chronic brain inflammation. Alzheimer's and other dementias are closely linked to sustained neuroinflammation; an estimated 55 million people worldwide live with a dementia diagnosis.
How the Spray Reaches the Brain
The core problem of many brain therapies is the biological barrier between bloodstream and brain: it protects the brain from foreign substances but also blocks most medications. Nasal sprays bypass this obstacle through smell nerves in the nasal mucosa, which have direct connections to the brain. Shetty's working group used as active ingredient so-called extracellular vesicles (EVs), nanometer-sized vesicles shed by human neural stem cells. These EVs transport microRNAs and other regulatory messengers that specifically intervene in the inflammatory signaling cascade. According to the study published in the Journal of Extracellular Vesicles (DOI: 10.1002/jev2.70232), they reach the hippocampus, the brain's memory and learning center, through this nasal route.
What the Study Actually Shows
After two spray doses, the aging test animals showed significantly lower activity in both measured inflammatory pathways. Mitochondria in nerve cells worked more efficiently and in memory tests, treated mice performed significantly better than untreated age-matched controls. Particularly remarkable is persistence: improvements according to the study lasted over several months after the final dose. Texas A&M filed a patent application. Results applied equally to males and females, which is significant for future human studies. Many older preclinical studies tested only one sex and failed in follow-up studies because the effect was absent in the other.
How Long Such Discoveries Take to Reach Humans
The EV spray represents a wave of research approaches using chronic brain inflammation as a target. How long such paths take is shown by the history of Alzheimer's therapy: Donepezil was identified as a promising substance in 1983 and received FDA approval in 1996, 13 years later. Lecanemab, the first drug proven to slow Alzheimer's progression, went through over 20 years of development until approval in 2023. In October 2025, the Institute of Bioengineering of Catalonia (IBEC) in Barcelona reported nanoparticles that dissolved Alzheimer's deposits in mice, with the same caveat: promising in animal models but years away from human trials. The common thread in all these approaches is that they target actual biochemical mechanisms that can be measured and changed.
Three Conditions for the Path to Human Studies
Before the spray can be tested in humans, several prerequisites must be met. First, efficacy and safety must be confirmed in a primate model, since results from mouse studies frequently do not reproduce in humans. The research team plans further animal studies as an immediate next step. Second, systematic dosing data is needed. Retinoic acid compounds are potent and at excessive concentrations can themselves damage cells. Compound 7 showed no toxicity in previous experiments, but dose-finding studies are entirely lacking. Third, the clinical indication must be clearly defined. Alzheimer's and Parkinson's differ substantially in affected brain regions and cell types. Whether a single drug class can address both diseases or whether specific variants are needed remains open.
Dr. Shetty estimates that human clinical trials could begin at the earliest in a few years. For affected individuals, this is no immediate improvement. But the mechanism works in the animal model, can be measured from outside, and targets an inflammatory process that is equally demonstrable in humans as in aging mice.