Having practised psychiatry for 24 years, I was pleased to see that the value of the mouse ‘forced-swim test’ is being called into question by researchers studying human depression (Nature 571, 456–457; 2019). Besides being shockingly cruel, this behavioural test misses the mark in approximating clinical depression in people.

Physical and emotional abuse (such as that associated with the test) is likely to induce hopelessness in humans and animals alike. In my experience, however, hopelessness is just one symptom of clinical depression in humans; abused people do not always meet the full criteria for major depressive disorder; and most individuals with the disorder are not currently being abused.

In my view, the complexity of human-brain function means that interpretations based on simplistic animal-behavioural testing are questionable. Data from clinical studies and from technologies that use human induced pluripotent stem cells offer a more rational approach for research into mental health.