From the article:
At 24 hours, mice treated with DHA, but not EPA, had a significant reduction in brain injury. In the following weeks, the DHA group also had significantly better results in multiple brain functions compared to the EPA-treated mice and untreated (control) mice.
The researchers also discovered that these mice had increased concentrations of DHA in their brain mitochondria, energy-producing structures in cells that can be injured by free radicals when blood flow is restored to the brain after a stroke.