Scientists Discover Sex Differences in How a Nasal Spray Reaches the Brain

A study published in the journal Genomic Psychiatry has found that the same intranasal medication may reach and affect the brain differently in men and women, highlighting important differences in the so-called “nose-to-brain” drug delivery system.

Researchers investigated a method in which a medication is administered as a nasal spray and travels directly to the central nervous system through the olfactory pathways, bypassing some of the body’s protective barriers. This approach is considered a promising strategy for treating brain disorders, including cognitive impairment and neurodegenerative diseases.

In the study, older adults with normal cognitive function as well as individuals with mild memory impairment received intranasal insulin. Using PET imaging, researchers tracked how the drug was distributed throughout the brain. They found that in participants with preserved cognitive function, the insulin more effectively reached brain regions involved in memory. In contrast, individuals with early cognitive impairment showed weaker and less sustained distribution of the drug.

The researchers also identified notable differences between men and women. Patterns of drug distribution, as well as their relationship to vascular health and biomarkers of brain health, varied by sex. These findings suggest that the effectiveness of nose-to-brain drug delivery may depend not only on age and brain condition but also on biological differences between individuals.

The authors emphasize that nose-to-brain delivery systems could become an important tool for treating neurological disorders. However, their effectiveness may need to be tailored to individual patient characteristics, including sex and vascular health status.

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