In a mouse model of Alzheimer's disease, a drug called trofinetide – which mimics the hormone IGF‑1 – helped the mice think better, lowered the build‑up of harmful amyloid plaques, and reduced brain inflammation and cell death. The same benefits were seen in lab-grown brain cells exposed to toxic amyloid fragments.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive impairment, neuroinflammation, and neuronal apoptosis. Trofinetide, an analog of insulin-like growth factor 1 (IGF-1), has shown neuroprotective effects in various neurological disorders, but its role in AD remains unclear. Six-month-old APP/PS1 transgenic mice received intraperitoneal trofinetide for 2 months. Cognitive function was assessed using the Morris water maze (MWM) test. Immunohistochemistry (IHC) and immunofluorescence (IF) evaluated β-amyloid (Aβ) pathology, microglial activation, and neuronal loss. In vitro, BV2 microglial cells and HT22 hippocampal neurons were treated with trofinetide against AβO-induced cytotoxicity. Western blot (WB) was used to analyze inflammation and apoptosis-related proteins. Trofinetide significantly improved cognitive deficits, reduced Aβ plaque deposition, and decreased microglial activation and neuronal loss in APP/PS1 mice. In vitro, it rescued AβO-induced cytotoxicity, suppressed inflammatory cytokines (TNF-α, IL-6, IL-1) in BV2 cells, and inhibited apoptosis in HT22 cells. Mechanistically, trofinetide upregulated PPAR-γ, reduced BACE1, suppressed NF-κB phosphorylation, inhibited caspase-3 activation, and restored Bax/Bcl-2 balance, alleviating neuroinflammation and apoptosis. This study provides the first evidence that trofinetide improves cognitive function and mitigates Aβ pathology, neuroinflammation, and apoptosis in APP/PS1 mice and AβO-treated cells, highlighting its therapeutic potential for AD.