A new hope for Parkinson’s sufferers?

1 out of 350 adults in the UK will be diagnosed with Parkinson’s disease in their lifetime. It is the second most common neurodegenerative disorder that becomes increasingly common over the age of 60. As this disease has such a large impact on society, you may be wondering what is being done to bring an end to its impact in ageing communities.

Parkinson’s disease results in reduced dopamine levels due to damaged nerve cells. This affects most aspects of movement causing tremors, loss of balance, and even difficulty with speech. Parkinson’s is also degenerative, meaning it will worsen with time. Unfortunately, current treatments only help to alleviate symptoms and do not slow its progression. This leaves some severely disabled in the later stages of Parkinson’s, with no independence and needing full-time care.

However, there is potentially hope on the horizon.

The results of a new experimental treatment for Parkinson’s disease have just been published. The lead researcher Dr Alan Hone is now “focused upon analysing and understanding the results” and says that their aim “is to communicate these to people affected by Parkinson’s as soon as we can”. This new treatment involves infusing glial cell line-derived neurotrophic growth factor (GDNF) directly into affected areas of the brain.

GDNF structure
Source: Wikipedia

GDNF is a naturally-occurring protein in the brain which protects and promotes the survival of neurons: specifically, dopaminergic neurons – the type that are lost in Parkinson’s patients. Due to this, GDNFs are suitable candidates for a treatment that could reverse the effects of the disease. Since the discovery of GDNFs in 1993, there have been multiple promising experimental animal studies of its effects on dopaminergic neurons.

It was the hope generated by the first studies that prompted testing this new drug in human trials. However, there was no improvement in the health of those receiving GDNF compared to the placebo, making the results disappointing. It was thought this was due to the drug not penetrating deep enough to reach the dopaminergic neurons within an area of the brain called the putamen.

As a result of the previous studies’ lack of clinical significance, a new method was opted for in the aforementioned new experimental treatment. This was specifically a convection enhanced delivery (CED) system, which would allow the drug to be delivered ultra-precisely. Forty-one patients underwent robot-assisted surgery where four tubes were implanted into their brain, which allowed the infusion of the drug directly to the target area.

For the first stage across nine months, the patients received either GDNF or placebo infusions. Going onto the second stage, all the participants were given the opportunity to receive GDNF treatments for a further 9 months, to which they all agreed.

While the first nine months of the study showed that there was no significant difference in the symptoms of the GDNF and placebo group, the brain scans showed much more promising results. After nine months of treatment with GDNF there was 100% more activity in a part of the brain called the putamen compared to no improvement within the placebo group. To top it all off, after the patients received GDNF for a further nine months, there were moderate to large improvements in the Parkinson’s associated symptoms. However, this stage lacked a control group so this could boil down to a placebo effect.

Aside from the uncertainty surrounding the results, the GDNF trial has still benefited those suffering from Parkinson’s disease, whether it be placebo or not. Christine Proctor, a grandmother of two, is a great example of this. Since taking part in the trial, she has seen significant improvements in her condition, saying, “the difference GDNF made was most definitely life-changing for me”. Ms Proctor has now gained more independence and a better quality of life thanks to the trial. Before it, she “couldn’t get out of bed without [her] meds”. She has even since taken a trip to New Zealand which is something she “never would’ve dreamed of doing before the trial.”

All in all, there is hope that GDNF has a regenerative effect on dopaminergic neurons in humans. The researchers have also suggested that future trials would require treatment across 80 weeks at a higher dose to see larger improvements, so the potential exists for the benefits of GDNF to be more dramatic. While the jury is still out on whether GDNF is effective, it still has the potential to be a viable treatment for patients suffering from Parkinson’s disease with further testing.

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