Japanese researchers helped a mouse forget bad memories by administering a dementia drug, and said the finding could lead to new treatments for patients with post-traumatic stress disorder (PTSD).

Satoshi Kida, a University of Tokyo chemistry professor, said Aug. 2 that his team confirmed the effects of memantine through the experiment.

People often develop PTSD as a result of terrifying circumstances, and feel a sense of terror when recalling such memories.

A common therapy for the condition is having patients speak about their experiences to medical professionals. However, the process takes time and puts a heavy burden on patients.

Kida and his colleagues placed a small mouse weighing 30 grams near a 40-gram mouse that exhibited threatening behavior, for 10 minutes a day for 10 consecutive days.

The smaller mouse displayed signs of PTSD and stayed away from the larger rodent. But once it took memantine weekly for four weeks, it started approaching the larger one without fear.

The scientists observed the behavior by placing the mice in a partially walled, round stand that was 50 centimeters high, for five minutes at a time.

While the PTSD-affected mouse feared the non-walled sections, staying there for only 20 seconds, the duration lengthened to around 50 seconds after the animal's condition improved with the drug injections.

Memantine likely promoted nerve regeneration in the area of the brain associated with memories, helping the mouse forget its fearful experience, the researchers said.

"We confirmed that administering memantine can ease anxiety-driven behavior," said Kida. "If the method is applied to humans, it may become possible to treat patients affected by earthquakes and other disasters."

The findings were published in the British journal Molecular Brain (https://doi.org/10.1186/s13041-019-0488-6).