Intranasal davunetide didn't significantly improve cognitive test scores in schizophrenia but did improve real-world functional capacity, suggesting the peptide may benefit practical abilities that tests don't capture.
d = 0.74 functional improvementA medium-to-large effect size for functional capacity improvement with the 5 mg dose — a meaningful real-world benefit even though formal cognitive test scores didn't reach significance.
What the researchers found
Intranasal davunetide (NAP peptide) did not significantly improve cognitive test scores (MCCB) versus placebo in 63 people with schizophrenia over 12 weeks. However, it did significantly improve functional capacity — the ability to perform real-world tasks — as measured by the UPSA (p = 0.048).
The 5 mg dose showed stronger effects than 30 mg, with effect sizes of d = 0.74 for functional capacity and d = 0.34 for cognition. The peptide was well tolerated with no significant side effects. The authors estimated 45–50 subjects per group would be needed to detect significant cognitive effects in future trials.
Why it matters
Cognitive dysfunction is the biggest predictor of disability in schizophrenia, yet no approved drugs effectively treat it. Antipsychotics control hallucinations and delusions but do almost nothing for thinking problems. Davunetide's improvement of functional capacity — even without clear cognitive test score improvements — is intriguing because real-world functioning is ultimately what matters most for patients. The dissociation between test scores and functional outcomes raises important questions about how we measure cognitive benefit.
The numbers in context
n=63 · 3 arms (5 mg, 30 mg, placebo) · 12 weeks · MCCB cognition: p = 0.45 (not significant) · UPSA functional capacity: p = 0.048 (significant) · effect sizes: d = 0.74 (5 mg UPSA), d = 0.48 (30 mg UPSA), d = 0.34 (5 mg MCCB) · 0 significant adverse events
How the study worked
Multicenter, double-blind, parallel-group randomized clinical trial. 63 adults with schizophrenia were assigned to intranasal davunetide at 5 mg, 30 mg, or placebo for 12 weeks while continuing their current antipsychotic medications. Cognition was assessed using the MATRICS battery (MCCB), and functional capacity using UPSA and SCoRS scales.
Who was studied
63 adults with schizophrenia, continuing their current antipsychotic medications, from multiple US centers
What this study cannot tell us
Small sample size (n=63 across three arms, ~21 per group) — underpowered to detect moderate cognitive effects. The primary cognitive measure (MCCB) was not significant. Only 12 weeks of treatment — longer durations might show different results. The significant UPSA finding could be a chance result given the small sample and multiple comparisons. Davunetide was later discontinued for progressive supranuclear palsy, which may have dampened enthusiasm for schizophrenia development.
How to read the evidence
Moderate evidence: a well-designed, multicenter, double-blind RCT with appropriate outcome measures. However, the small sample size (n=63 across three arms) limits statistical power. The primary cognitive endpoint was negative; the significant functional finding, while encouraging, comes from a secondary measure in an underpowered study.
When this study was published
Published in 2012. Davunetide's clinical development was later discontinued after failing in a progressive supranuclear palsy trial (2014). The schizophrenia indication was not further pursued, but the findings remain relevant to neuroprotective peptide research.
The bigger picture
Davunetide (NAP) is derived from activity-dependent neuroprotective protein (ADNP) and was one of the more promising neuroprotective peptides to reach clinical trials. This schizophrenia trial is notable because it found an effect on functional capacity — what patients can actually do in daily life — even when traditional cognitive tests missed it. This dissociation has influenced how the field thinks about measuring treatment benefits. Though davunetide's development stalled after a failed progressive supranuclear palsy trial, the NAP peptide concept continues to influence neuroprotective research.
Questions still open
- Why did davunetide improve functional capacity but not cognitive test scores — are the tests missing something important?
- Would a larger, longer trial with the 5 mg dose show significant cognitive improvements alongside functional gains?
- Could other neuroprotective peptides succeed where davunetide's development stalled?
Common questions
What is davunetide and how does it work?
Why did davunetide improve functioning but not test scores?
Read the original research
Effect of the neuroprotective peptide davunetide (AL-108) on cognition and functional capacity in schizophrenia.
Schizophrenia research, 136(1-3), 25-31
Citation
Javitt, Daniel C; Buchanan, Robert W; Keefe, Richard S E; Kern, Robert; McMahon, Robert P; Green, Michael F; Lieberman, Jeffrey; Goff, Donald C; Csernansky, John G; McEvoy, Joseph P; Jarskog, Fred; Seidman, Larry J; Gold, James M; Kimhy, David; Nolan, Karen S; Barch, Deanna S; Ball, M Patricia; Robinson, James; Marder, Stephen R. (2012). Effect of the neuroprotective peptide davunetide (AL-108) on cognition and functional capacity in schizophrenia.. Schizophrenia research, 136(1-3), 25-31. https://doi.org/10.1016/j.schres.2011.11.001