Parkinson’s disease (PD)

Parkinson’s disease is a neurological disease that causes nerve cells to atrophy prematurely. Parkinson’s disease is the second most common primary neurodegenerative disease after Alzheimer’s disease. It is believed nearly nine million people are living with the disease globally and that this number will more than double by 2040. The disease is both chronic and progressive; in other words, it is both lifelong and worsening over time.

Debilitating, progressive and costly

The onset of Parkinson’s disease is usually after the age of 60, but it can also affect younger people. The exact cause of the disease is not known, and at present, there is no way to prevent the onset or slow down its progress. In recent years, several genetic defects have been identified, but overall, these only account for a minor share of all diagnosed cases.

The disease starts with motor symptoms such as a slowness of movement (bradykinesia), tremors and rigidity. These symptoms are caused by a deficit of the neurotransmitter dopamine in the brain. The progression of the disease also affects other nerve cells and neurotransmitter systems, and with time, an increasingly difficult balance impairment emerges, along with symptoms from the autonomic nervous system and cognitive disorders.

Levodopa improves mobility but causes dyskinesia

A gigantic leap in the treatment was made in the 1960s, when the dopamine deficiency was identified, and levodopa treatment was introduced. Levodopa, a precursor to dopamine, is converted to dopamine in the brain, replacing the dopamine that has been lost due to the disease. All of a sudden, patients who were previously bedridden or used wheelchairs were able to get up and walk! But nothing is all good. It was noticed early on that levodopa, which was so effective in reducing hypokinesia and tremors, eventually began to cause involuntary movements (dyskinesia). With time, the treatment became increasingly difficult to manage; patients fluctuated rapidly between reduced mobility and dyskinesia. The treatment may also cause the patient to hallucinate. People who suffer from this also often experience the feeling that someone else is present in the room, which can progress to visual hallucinations, and in severe cases, obvious psychotic symptoms with a distorted concept of reality.

No cure and no certain reason to why Parkinson’s occur

Parkinson’s disease entails slow degeneration of nerve cells that use the signal substance dopamine and decline of the dopamine level in the brain. Dopamine is an important signal substance in the brain. Parkinson’s disease is normally not discovered until nearly 80% of the nerve cells that signal using dopamine have been lost. There is currently no cure for Parkinson’s disease, and the mechanism underlying the disease is largely unknown.

Present treatments of Parkinson’s are entirely focused on symptom relief. The standard of care treatment is with levodopa, a drug that the body converts into the signal substance dopamine. Since its introduction in the 1970s, some new drugs have been introduced. These are based roughly on the same principle – the use of various methods to increase the transmission of dopamine, thereby improving mobility. To stabilize motor function, pump-controlled treatments with levodopa have been introduced, and the development of pump-controlled subcutaneous levodopa is still ongoing. An increasingly common method of treating Parkinson-related conditions that are difficult to treat is the surgical insertion of electrodes in the brain, referred to as deep brain stimulation (DBS). The method involves using high frequency electrical activity to disrupt any signals that contribute symptoms.

As the disease progresses, it becomes necessary to add several drugs to control symptoms (e.g. so called enzyme inhibitors). Research is being conducted in order to find a drug that slows the progression of the disease, but no clinical results have so far been obtained. Treatment options for those who suffer from Parkinson’s disease are currently far from optimal. At IRLAB, we are trying to find ways of addressing some of the greatest medical needs for those affected by the disease.