The Forced Swim Test has no more place in tackling mental illness than asylums or lobotomies
Published on February 23, 2023
As someone who has been dealing with mental health issues for most of my adult life, I am all too aware of the urgent need for medical progress in this field. I suffered from anorexia as a young adult, and after a break of almost a decade, have been dealing with eating problems again in recent times. I’ve grappled with various anxiety related disorders over the years, from Generalised Anxiety Disorder to a particularly troubling form of OCD that resulted in intrusive thoughts that I could suddenly lose control and commit some terrible act of harm. Having been through a fourth round of Cognitive Behavioural Therapy (CBT), I am on the road to recovery, although it’s never a straightforward process.
I know that this experience is far from unique, since one in four people in England will suffer from a mental health problem each year. Fortunately, awareness of mental health issues is growing and more people feel able to speak openly about them.
An area that has gained much less public awareness, however, is the hopelessly crude and outdated nature of some animal-based research into mental health disorders. Using animals to research mental illness is deeply counter-intuitive, given the obvious importance of being able to verbally describe symptoms. In fact, scientists acknowledge that the problems in translating results from animal-based research to human patients are likely to have contributed to the lack of progress in this area.
A particularly troubling example of mental health research on animals is the ‘Forced Swim Test’. This upsetting test, which dates back to the late 1970s, involves dropping mice or rats into a container of water from which they cannot escape. At first, they will swim, but after a while they will stop struggling, stay immobile and float. Comparing this test with the state of mental health treatment in the UK at that time highlights just how outdated it is. In the late 1970s, the large-scale closure of asylums had not yet taken place, and some lobotomies were still being performed. While such establishments and techniques have happily been consigned to history, the Forced Swim Test has not.
Unbelievably, this test has been used as a model for depression in humans. While my own encounters with depression have been secondary to anxiety disorders, and I haven’t experienced the debilitating symptoms that many people endure, I am confident that the feelings of despair and failure that I am familiar with are nothing like what must be experienced by a mouse or rat who is suddenly dropped into a situation of immense physical stress. In fact, it has been suggested that the ‘floating’ behaviour does not represent the animal ‘giving up’ in despair, but rather a learned behaviour that helps them to conserve energy.
A growing number of scientists now accept that dropping mice and rats into containers of water is hardly an accurate model of depression in humans. Yet the test is still sometimes used as a means of screening new antidepressants. The theory goes that drugs which reduce the amount of time the animals spend floating and immobile, are the ones which have the best potential for treating depression in humans. Unsurprisingly, there is a wealth of evidence to suggest that this test is not a reliable predictor of whether new antidepressants will be safe and effective in people. This includes an analysis of 47 potential new antidepressants that were given to animals subjected to the Forced Swim Test, which found that none of them were later considered safe and effective treatments for depression in humans. In fact, several major pharmaceutical companies have already abandoned the use of the test.
A further strand to this distressing story is the effect that carrying out animal experiments can have on the people involved. For example, a preliminary study in Poland found that 72% of survey respondents felt an emotional burden as a result of carrying out animal research, and 63% experienced stress.
Fortunately, modern, animal free techniques offer a much more ethical approach to mental health research and provide results that are directly relevant to human patients. Approaches include the sophisticated use of human cells and tissues and organ-on-a-chip technology. Non-invasive approaches to recording brain activity, such as electroencephalography (EEG) can provide valuable data which has even more potential when combined with analysis using artificial intelligence. Another promising area is re-purposing existing drugs, which are already known to be safe in humans, for their potential in treating mental health disorders.
There has never been a better time to overhaul mental health research and ensure that it is human relevant, fit-for-purpose, and offers the best possible chance of tackling conditions that can make everyday life feel difficult to cope with. The Government has recently commissioned a review of the Forced Swim Test and should take this opportunity to immediately stop allowing it to take place. Instead, it should provide practical support and funding to help researchers transition to the use of cutting-edge, human relevant techniques. This more enlightened and compassionate approach will bring us closer to a brighter future for both animals and people.
Isobel Hutchinson, Public Affairs Director
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