Did you know that Parkinson’s disease does not develop naturally in any animal except humans?

Despite the extensive use of monkeys in research, not one experiment has been able to completely reproduce the clinical symptoms and pathology of Parkinson’s disease seen in humans.

So today, on World Parkinson’s Day, while we think of those who are affected by this debilitating disease, we also reflect on the countless monkeys who continue to suffer and die in fruitless research.

The majority of Parkinson’s disease experiments involve artificially inducing similar symptoms in monkeys by injecting them with neurotoxins that damage the dopamine-producing cells in the brain.

After several days of dosing, the monkeys become disabled and cannot move properly. They have to be hand-fed to prevent them from starving to death. They are then usually dosed with the common treatment for Parkinson’s, levodopa, which, whilst freeing up the body to move, actually causes the debilitating shaking that people associate with the disease.

The UK Home Office has previously admitted that these procedures are some of the most severe in the country, with “devastating welfare costs” to the monkeys involved. In a 2015 report, we exposed this type of cruel research being carried out on marmosets at Kings College in London and criticised them for greatly downplaying the severity of the experiments to the public.

Not only are these experiments devastating for the monkeys involved, they are also ineffective.

Unlike the human disease, which is progressive and irreversible, symptoms in monkeys are immediate in response to the toxin and the effect often diminishes over time. Other fundamental differences from humans include the absence of Lewy bodies (abnormal proteins in the brains of people with Parkinson’s) and the absence of differences between males and females in susceptibility.

It is not surprising, therefore, that decades of monkey research have not resulted in any effective treatments for Parkinson’s or significant understanding as to its cause. Yet, researchers continue to waste time and resources on these pointless experiments.

In a recently published review, our scientists found that experiments on monkeys’ brains are flawed and misleading  due to important differences in brain structure and function between humans and monkeys. They also found that many researchers are incorrectly stating that these experiments are crucial to medical breakthroughs.

For example, advocates of monkey research often claim that macaque monkeys were indispensable to the development of deep brain stimulation (DBS), the much touted treatment for Parkinson’s Disease. In reality however, DBS was already being used in the late 1970s and 1980s in various parts of the brain including the basal ganglia to control tremor among other things, long before monkey experiments were conducted. Furthermore, the specific location in the brain relevant to Parkinson’s patients had been identified in the 1920s based on observations in humans.

Dr Jarrod Bailey, Senior Research Scientist at Cruelty Free International, said: “The increasing power of humane and human-specific testing methods renders monkey neuroscience research redundant.  Both the monkeys used in these cruel experiments and the people waiting for science to deliver better treatments for neurological diseases, will benefit from a move towards ethically and scientifically superior alternative methods of research.”

Why we believe monkey brain experiments are flawed and misleading.
 

Sources:

1. Distressing experiments carried out on monkeys in UK laboratories. (2015). Cruelty Free International, 5^th October: https://www.crueltyfreeinternational.org/distressing-experiments-carried-out-monkeys-uk-laboratories
2. Non-human primates in neuroscience research: the case against its scientific necessity. (2016). ATLA, 44: 43-69