What has research for Parkinson's been able to determine?

Medical experts and research teams have been able to determine some strongly linked contributing factors when it comes to the underlying cause of Parkinson’s disease.

The deterioration (breaking down) of neurons in the brain affects the production levels of dopamine. This causes a malfunction in brain activity and interferes with the normal ‘messaging system’ in the body that signals and controls motion ability, ultimately leading to signs and symptoms of the condition.

With that in mind, research has looked at the following contributing causal factors:

• Genes: It has been noted that at least 15% to 25% of those diagnosed with Parkinson’s disease have a family history of the condition. This sizable percentage is enough to assess level of potential risk. Having a close relative (first-degree relative), such as a sibling or parent, or a known history with multiple family members having been diagnosed with Parkinson’s appears to place a person at higher risk of developing the condition themselves. Gene mutation, a permanent alteration in DNA sequence, is thought to have the heaviest influence as to why Parkinson’s disease runs in families. Research in this area is ongoing.
• Environment: Chemical exposure has been researched as another potential causal link. On the list of researched substances are insecticides, fungicides, herbicides and ‘Agent Orange’ (a defoliant chemical used by U.S military troops during the Vietnam War as part of its herbicidal warfare programme). Other possible environmental links being researched include ingesting manganese (a chemical) and the drinking of well water (that is not filtered or purified). Exposure to chemicals is thus, largely tied to occupations, such as those that deal with toxic substances on a regular basis. Occupations in agriculture, welding or of an industrial nature are potentially at the most risk. Research has not shown that toxin exposure alone leads to Parkinson’s disease. Many believe it may play a role, but in combination with other factors, more specifically gene mutations.
• Lewy bodies: Abnormal clumps of proteins in the brain stem (as well as the midbrain and olfactory bulb) are known as ‘Lewy bodies’. Cells of protein (alpha-synuclein or A-synuclein) that are unable to adequately break down form clumps and cause disruption in normal brain function. Clusters of these protein clumps lead to the gradual degeneration of function over time and ultimately lead to impairments with motor coordination.
• Dopamine reduction / loss: A lack of dopamine production leads to a malfunction of neurotransmission function in the brain. The brain, effectively, is unable to send and receive messages that control smooth function and normal movement. Dopamine levels are balanced with another substance, known as acetylcholine (another chemical in the brain responsible for the transmission of nerve impulses). Imbalance between the two leads to coordination impairment and begins affecting a person’s capacity to walk or balance properly. It also affects non-motor functions such as sleep regulation and sense of smell. This cellular degeneration is being researched extensively in combination with gene mutation, as some experts believe that genes may have an influence and be the key to explaining why a breakdown occurs. Researchers believe that if it is possible to determine the sequence of events that lead to the development of symptoms, specifically the loss of dopamine and cell degeneration, better treatment methods can be developed to gain more control or reverse signs of the disease altogether.
• Gender and age: Research has taken into account the age and gender of the majority of diagnosed cases. As the body ages, dopamine production naturally alters, making an older person vulnerable to developing Parkinson’s disease. It has also been noted that men are more prone to developing Parkinson’s disease than women.

What genes have been linked to Parkinson’s disease?

Parkinson’s disease is classified as an idiopathic illness (one which occurs without a known cause), but through intense research, experts have identified several genes associated with the condition.

Scientific experts have investigated the possible causal links among family members who have all been diagnosed with the condition.

This research has proved incredibly valuable as it allows experts the ability to better understand the nature of Parkinson’s disease, which in turn allows medical professionals an opportunity to potentially develop and implement more effective treatment and therapies.

Through research, the following genes have been conclusively identified with strong links to Parkinson’s disease:

• PARK2 (Parkinson’s disease autosomal recessive, juvenile 2): This gene produces parkin (a protein), which has been identified mostly in those diagnosed with juvenile Parkinson’s disease. Normally this protein assists cells with functions of breaking down and recycling proteins but in those with juvenile Parkinson’s disease, mutations of the gene occur causing dysfunction within this process.
• PARK7 (Parkinson’s disease autosomal recessive, early onset 7): This gene produces the DJ-1 protein, which is responsible for protecting cells from oxidative stress. Mutations of PARK7 were identified in early-onset Parkinson’s disease.
• PINK1 (PTEN-induced putative kinase 1): Researchers have not been able to conclusively establish what the purpose of the protein made by PINK1 is, but they suspect that it protects the mitochondrial cell structures from stress. Gene mutations have been identified in early-onset Parkinson’s disease.
• SNCA (Synuclein, alpha non A4 component of amyloid precursor): This gene produces the protein, alpha-synuclein, which is known to form clumps called Lewy bodies. Research has identified these genes in early-onset Parkinson’s disease and noted distinctive mutations in the SNCA gene.
• LRRK2 (Leucine-rich repeat kinase 2): This gene produces dardarin (a protein). Gene mutations have been identified with late-onset Parkinson’s disease.

Other genes have been identified and are being researched as potential links to Parkinson’s disease. These are SNCAIP (synuclein alpha interacting protein), GBA (glucosidase beta acid) and UCHL1 (ubiquitin carboxyl-terminal esterase L1).