Levodopa May Not Be the Best Option for Parkinson’s Treatment, Study by Students Contends

Levodopa May Not Be the Best Option for Parkinson’s Treatment, Study by Students Contends

Levodopa improves Parkinson’s patients’ symptoms by binding with two types of receptors for dopamine, a neurotransmitter that helps regulate movement and emotional response.

Although it is considered the gold standard in Parkinson’s treatment, a study from Binghamton University students contends that levodopa’s interaction with the dopamine receptor D2 may cause involuntary muscle movements, compulsive behaviors, and hallucinations.

The research, “Effects of Receptor-Specific Dopamine Drugs on the Treatment of Cognitive Deficits in Parkinson’s Disease,” appeared in the The Undergraduate Journal of Psychology at UCLA.

Parkinson’s is a progressive neurodegenerative disorder that affects movement, muscle function, and speech. It is characterized by gradual loss of nerve cells that contain the neurotransmitter dopamine. They are located in a brain area called substantia nigra that is essential to the control of movement.

Dopamine binds to two classes of receptors — D1 and D2. Levodopa, which is also called L-DOPA, is a naturally occurring molecule that generates dopamine. It binds to both D1 and D2 receptors to replenish the disease-related lower levels of dopamine, improving Parkinson’s symptoms.

The New York State university research team triggered the formation of brain lesions in rats to mimic the loss of nerve cells in Parkinson’s. Rats were then treated with levodopa or compounds that bind with either D1 or D2 receptors, but not both. The next step was for rats to be tested for movement, ability to pay attention, and spatial memory.

Although activating D2 receptors with quinpirole improved the rats’ spatial memory, it led to  attention loss in both rats with brain lesions and controls. In contrast, activating D1 receptors did not lead to significant differences, in comparison with levodopa.

Overall, the findings suggested that, because levodopa stimulates D2 receptors, it may not be the best choice for Parkinson’s treatment.

“Parkinson’s disease is one of the most common neurodegenerative diseases in the world,” Lakshmi Hareendran, a member of the research team, said in a press release. “Knowing that the current treatment isn’t as effective as it could be is important.”

“In conclusion, the quinpirole effects on memory and attention ability is an essential discovery. Uncovering the mechanisms underlying these actions may lead to the development of a more effective treatment for [Parkinson’s] that covers both motor and cognitive deficits in humans,” the researchers wrote.

Hareendran comes from a family with several doctors and has an uncle who is a brain surgeon. “As a kid, just thinking about him being able to understand something as complex as the human brain really inspired me to go down that path,” she said. She plans to work with Doctors Without Borders some day.

10 comments

  1. Joann says:

    If not l-dopa, then what’s the alternative ? L-dopa, the “gold standard”, is the only standard – over 60 years since it was developed and hundreds of billions of dollars later , there is nothing else. Why ???? Almost in believable

  2. Jay says:

    Sad that studies such as this one just target the bad on the one medicine that brings a bit of hope. So, if L-dopa is not good what other medicine is out there for those who suffer Parkinson? it’s 2018 We need a cure for this disease now!

  3. Allan says:

    I know we will not be seeing any cures for Parkinson’s from Pfizer ever as they recently halted all research on Parkinson’s and Alzheimers because these medications will not bring profits to Pfizer’s stockholders. I’m wondering if their CEO or the other executives get Parkinson’s in their mid 50’s as I did, how would they feel about their decision.

    Obviously there is more money in Viagra for Pfizer. That of course is more important to the Pfizer executives.

  4. Anthony says:

    Levadopa was developed in the early 1960’s and it’s sad that it remains the Gold Standard of treatment for Parkinson’s. James Parkinson discovered the “Shaking Palsy” aka Parkinson’s 201 years ago.

    Do we have to wait another 200 years for a cure? Thanks Pfizer

    • Patrick says:

      Levodopa doesn’t always help with Tremors which are not present in all forms of Parkinson’s. The cardinal feature is slowness of movement or inability to initiate movement, not tremor. If he has s,ow movements and the levodopa does nothing for him: He’s been misdiagnosed and you need to find another neurologist.

      In reference to the article itself; Levodopa does not cause hallucinations, compulsive behaviors and has little to do with cognition or spatial memory. Note the article was written by psycholgists who have absolutely no understanding of Parkinson’s, not Neurologists who deal with the full range of symptoms and it’s treatments everyday. I woyuld encourage them to take up a new hobby.

  5. David says:

    We have several posts, not necessarily relevant to the discussion.
    Apparently the Journal wanted a Titillating headline.
    L-dopa has been very successful in comparison to anything else. It isn’t successful for everyone. It isn’t a cure. It induces side effects.
    Most searches have been aimed at boosting L-dopa with an agonist, enabling it to be more successful and smooth out its deficiencies, as well as reduce complications (LID). Pfizer and everyone else have sunk Billions into this search, with poor results. The receptor discussion is intriguing but incomplete. There are not just 2 receptors. Improving receptors is a potential improvement. Overall exclusively looking at pharmacology seems to be the reason for a lack of success. DBS is highly invasive but can be succesful without changing chemistries and, typically, reducing drug reliance. Ideally less invasive electrophysiology approaches could attain similar benefits. Curiously, TrCrMS has been in view for 3 decades without really breaking out.

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