Parkinson’s disease is a neurological disorder that researchers are still studying in order to determine the cause. While the etiology has not been identified yet, researchers have pinpointed some variations that happen.
Low dopamine levels
Some research suggests that Parkinson’s disease symptoms may be due to low or decreasing levels of dopamine, which is a neurotransmitter. It occurs when cells that produce dopamine die in the brain.
Dopamine helps with sending messages to the part of the brain that controls movement and coordination. Low dopamine levels can make it more difficult for people to control their movement. As dopamine levels continue to fall, symptoms gradually become more severe.
Low norepinephrine levels
Parkinson’s disease may also result from damage to nerve endings that produce norepinephrine, which is another neurotransmitter. It contributes to blood circulation and other automatic body functions. Low levels of norepinephrine in Parkinson’s disease may increase the risk of both motor and nonmotor symptoms, such as:
- stiffness and rigidity
- postural instability
- tremor
- anxiety
- difficulty focusing
- dementia
- depression
This may help explain why individuals with Parkinson’s disease frequently have orthostatic hypotension. This is the scientific name for that sensation of lightheadedness and dizziness when you stand up.
Lewy bodies
A person with Parkinson’s disease may have clumps of protein known as alpha-synuclein, or Lewy bodies, in their brain. The accumulation of Lewy bodies can result in a loss of nerve cells and changes in thinking, movement, behavior, and mood. It may also result in dementia.
Lewy body dementia is not the same as Parkinson’s disease, but people may have both as the symptoms are similar.
Genetic factors
Researchers have found changes in certain genes appear to be linked with Parkinson’s disease, but they do not consider it to be a hereditary condition. Genetic factors appear to cause only 10% of cases, mostly among people with early-onset disease.
Autoimmune factors
In a 2017 study, scientists found a possible genetic link between Parkinson’s disease and autoimmune conditions, such as rheumatoid arthritis. In 2018, researchers investigating health records in Taiwan found that people with autoimmune rheumatic diseases had a 1.37-higher chance of also having Parkinson’s disease.
Risk factors
Several environmental factors may increase the risk of developing Parkinson’s disease.
These include:
- Past traumatic brain injury: Head injuries from contact sports, for example, may increase the risk of the condition.
- Toxin exposure: Such as pesticides, solvents, metals, and other pollutants.
- Gender: Males are 50% more likely to develop the condition than females, although one 2016 study suggests the risk for females may increase with age.
- Age: The condition often appears from the age of 60 years.
- Some drugs and medications: Certain medicines can lead to Parkinsonism, where a person has tremors and other symptoms but does not have Parkinson’s disease.
Symptoms usually appear from the age of 60 years. However, 5–10% of people with the disease have early-onset Parkinson’s, which starts before the age of 50 years.