But some scientists involved in chimp-assisted research challenge the validity of Ferdowsian’s study and the proposed ban.

John VandeBerg, a biomedical researcher and director of the Southwest National Primate Research Center in San Antonio, Texas, finds serious flaws in the study and considers its conclusions invalid.

"The authors appear to have tried to assign a human disorder, Post Traumatic Stress Syndrome, to these chimpanzees and this syndrome is defined primarily by psychological characteristics such as persistent nightmares, recurrent distressing feelings about the event that they have suffered," says VandeBerg. "Chimpanzees aren’t able to relate to us whether they are having nightmares or recurrent, distressing recollections.”

'Devastating blow'

VandeBerg, who uses chimpanzees in the medical research he conducts at his Texas facility, says the animals are treated humanely.

“We have many chimpanzees here at the Southwest National Primate Research Center that have been here for many decades, who’ve been used in experimental research over many decades. They do not exhibit symptoms of depression, and certainly as I say, there is no way of diagnosing Post Traumatic Stress Syndrome.”

VandeBerg says chimpanzee research has led to life-saving medical gains.

“For example, the Hepatitis B vaccine would not have been developed without research with chimpanzees. Hepatitis B vaccine was given to the children in 116 countries of the world. That was a huge medical breakthrough which will save hundreds of millions of human lives.”