Our purpose of the present this literature review is  that we would like to discuss about Parkinson patiences whose are using L-Dopa  and we are making review the effects of L-dopa medication in Parkinson’s disease on cognitive functions in the broad domains of cognitive flexibility and working memory. In another word, the purpose of the present article is to review the positive effects of L-dopa medication in Parkinson’s disease and this medication is used to treat  symptoms of Parkinson’s disease or Parkinson-like symptoms, such as shakiness, stiffness, difficulty movingand etc. According to Neuroscience and Biobehavoral,  Parkinson’s disease exhibit cognitive deficits, even in the earliest disease stages. Whereas, L-dopa therapy in early Parkinson’s disease is accepted to improve the motor symptoms, the effects on cognitive performance are more complex: both positive and negative effects have been observed. We are searching positive effect on the Parkinson patience.

When you have Parkinson’s, your brain gradually stops making dopamine a chemical that helps send signals in your brain. Medicine can often keep your symptoms in check for years. Your doctor may suggest you try drugs and levodopa is one of them also you may hear your doctor call this L-dopa. 

We have learnt that Parkinson’s disease is a movement disorder and it affects elderly population about 1-2% of middle age people and old people. Intially, Parkinson semptoms seem mildly but they inevitably incerase in harshly with upcoming years. Most common semptoms are muscular rigidity, difficulty initiating movement, slowness of movement, masklike face and also  pain, depressing , often develop before the motor syptoms are becoming severe. Scientists say that Parkinson’s disease seems to have no single cause such as faulty genes, brain infectious, strokes, tumors , traumatic brain injury etc., and neurotoxins have all been implicated in specific cases.

According to Parson biopsychology book, “Parkinson’s disease is associated with widespreade degeneration, but it is particularly severe in Substantia nigra-the midbrain nucleous whose neurons Project via the Nigrostriatal pathway to the Striatum of the basal ganglia. Also we have learned about Lewy bodies , they are named after  German doctor who first identified them, they are abnormal group of protein that develops inside nerve cells and are a marker for Parkinson disease. According to Pearson biopsychology book, We have learned about the case of d’Orta. We should look briefly what was happening in Mr d’Orta’s brain. He was strong business man, he had Parkinson but it happend slowly and he turned a pieces of granite, because he had rigit muscle, hand shake worse, walked in shuffling steps, difficulty in starting to move and etc. His neurologist prescribed L-dopa, and it worked, his feet no longer shuffled. He was able to perform with easy some activites of  daily life ,  “the semptom of Parkinson’s disease can be alleviated by injections of L-dopa-the the chemical from which the body synthesizes dopamine. “[1]

We have search about the L-dopa and its benefit for the Parkinson patience, there are significant study about it and we will examine some article.

According to the article, Parkinson’s disease  is thought to be caused by too little of a naturally occurring substance (dopamine) in the brain . Levodopa changes into dopamine in the brain, helping to control movement.  Carbidopa prevents the breakdown of levodopa in the bloodstream so more levodopa can enter the brain. Carbidopa can also reduce some of levodopa’s side effects such as Nausea and vomiting.[2]

According to researchers, dopamine is not an effective treatment for Parkinson disease because it does not readily penetrate the blood-brain barrier. However, knowledge of dopaminergic transmission has led to the development of an effective treatment: L-dopa, the chemical precursor of dopamine, which readily penetrates the blood-brain barries and is converted to dopamine once inside the brain.[3]

We see in this research that, 3,4‐dihydroxy‐L‐phenylalanine (L‐DOPA) is the gold standard treatment for Parkinson’s disease. It has earned that title through its highly effective treatment of some of the motor symptoms in the early stages of the disease but it is a far from perfect drug. The inevitable long‐term treatment that comes with this chronic neurodegenerative condition raises the risk significantly of the development of motor fluctuations including disabling L‐DOPA‐induced dyskinesia. Being unsurpassed as a therapy means that understanding the mechanisms of dyskinesia priming and induction is vital to the search for therapies to treat these side effects and allow optimal use of L‐DOPA. However, L‐DOPA use may also have consequences (positive or negative) for the development of other interventions, such as cell transplantation, which are designed to treat or repair the ailing brain. This review looks at the issues around the use of L‐DOPA with a focus on its potential impact on advanced reparative interventions.[4]

As reported by neurosciences,  “Parkinson’s disease (PD) is a neurodegenerative disorder characterized by dopaminergic neuronal loss in the substantia nigra parscompacta (Braak et al., 2003). Dopamine deficiency leads to dysfunctionin multiple, topographically organized cortico-striatal circuits, consequently giving rise to motor symptoms as well as cognitive and emotional problems. The pathology in Parkinson disease is not limited to the neuronalcell bodies. Studies using animal and cell culture models of Parkinson disease have demonstrated that neurodegeneration is also associated with axonopathy and synaptic dysfunction, and impairs white matter integrity (Burke and O’Malley,2013;O’Malley, 2010;Tagliaferro et al.,2015.) Neuroimaging studies have also provided evidence for differential effects of dopaminergic states on striatal functional connectivity patterns. In a study with drug naive de novo PD patients, the striatal dopamine levels correlated differentially with the resting-state whole-brainfunctional connectivity patterns of the caudate and putamen seeds.”[5]

We look another study about L-dopa, “Next to undertake clinical research was Yahr et al.Columbia University, whose study with levodopa was double-blind and prospective. It included some patients who crossed over between placebo and active treatment. Comprising the clinical population were 56 patients with presumed idiopathic Parkinson disease, 3 patients with postencephalitic parkinsonism, and 1 patient with probable progressive supranuclear palsy. This study, published in the same year as the second report by Cotzias et al.,  administered levodopa 3–5 times per day, starting with a daily intake of 750– 1,000 mg. The maximal dose was 8 g/d, and in the study, the optimal effect for some patients was that dose or as low as 3 g/d.The study results confirmed the dramatic improvement of parkinsonism previously reported by Cotzias et al.In the study by Yahr et al.,improvement was “marked” or “complete” for two-thirds of the patients. The results of the trial by Yahr et al., opened the support of the pharmaceutical industry to make this compound available (using a newly developed chemical chirally- specific synthesis methodology that would one day help to win a Nobel Prize). Linked to the further development of levodopa was the coadministration of carbidopa or another inhibitor of peripheral L-aromatic amino acid decarboxylase, benserazide. Each greatly reduced many of the adverse effects and permitted easier introduction of the drug by clinicians.” [6]

In conclusion, Our findings also raise concerns about usefulness of L-dopa, it has to effective to movent and learning-enhancing properties. Unfortunately, there are some side effect such as nausea, loss hair, hypertension, but Clinicians try to avoid these side effects and adverse reactions by limitingL-dopa doses as much as possible until  necessary. Our literature review indicated that the L-dopa was appropriate to induce the effects of interest with positive-effects, but we cannot completely rule out the possibility that L-dopa  can have negative effects according to amounts and using period., also L-dopa’s use has important consequences on the Parkinson disease such as orally or intravenously.


John P.J. Pinel – 4 EDITION-Biopsychology-Pearson (2010)

[1]John P.J. Pinel – 4 EDITION-Biopsychology-Pearson (2010)






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Published by Minerva's Wings

Welcome my blog! I started this blog to share my experiences about learning and teaching.

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