Why do you think that the initial conditions were so inappropriate? Were they necessary?
That’s a question I am unable to answer. Was biomedical research necessary in great apes? I actually don’t know for sure. Maybe to this extent, it wasn’t necessary. But I also don’t want to accuse anybody for this, because perhaps some 30 years ago, most people didn’t know that these animals are so vulnerable to developing abnormal behaviors and psychopathology.
Is it appropriate to refer to the chimps as suffering from mental illness?
It’s a very good question. I think we don’t have a better language than [what] we also use for human pathology. We can safely say, I think, that they suffer from depression and post-traumatic stress disorder, based on the common causes of these disorder in apes and humans, and based on the observation of the behavioral signs.
Is there any kind of standard system for diagnosing apes, like the DSM [Diagnostic and Statistical Manual of Mental Disorders] for humans?
No, this doesn’t exist.
Well, it should. But I think it would be very difficult to come to this point. Even if you can improve the conditions of the chimps, they still have these abnormal environments. So you cannot expect that they come back to an entirely normal behavioral repertoire. The baseline actually is the behavior in the wild, and any deviation from behaviors observed in the wild perhaps can be classified as abnormal.
You wrote a letter in 2004 to Science suggesting psychiatric treatment for lab chimps. What prompted you to do that?
The concept was discussed during a coffee break at a conference where I met Professor [William] McGrew, who is a well-known primatologist. We were thinking, “Hey, can we perhaps write that, for some of the really worst cases, maybe psychiatric treatment could be an appropriate measure.”
And what was the response?
The response was poor, I would say. There was very, very little response to the letter. And so we expanded on these sketchy ideas and wrote a larger review article that was published in another journal called Neuroscience & Biobehavioral Reviews. So I think it’s one contribution among many that go in the same direction.
Do you think the scientific community has a different approach now than it did in 2004?
For some reason, I think there is more public attention now, especially with regard to the ethical issues associated with the treatment of chimpanzees in captivity. And that’s a fairly recent development. But it’s good.
Can you tell me about the research in the Netherlands that you’re working on now?
I wouldn’t call it research because it’s not a proper study. What’s going on there is a behavioral observation of chimpanzees who receive behavioral treatment—and some of them medication—in comparison with a control group. But I wouldn’t call it an experiment. It’s more like a naturalistic study.
What medication do they get?
Well, this was my suggestion to use sertraline as a serotonergic drug [one that affects levels of the neurotransmitter serotonin in the brain], for several reasons. In humans, it’s available for treating depression, obsessive-compulsive disorder, binge eating disorder and panic disorder. Because the signs and symptoms observed in the chimps somehow resemble depression, anxiety, and also PTSD, I thought it might be a good idea to start with an SSRI [selective serotonin reuptake inhibitor]. I thought sertraline would perhaps produce the least side effects. And it seems to work very well.