There may be a link between attention deficit hyperactivity disorder (ADHD) and Parkinson’s disease, as they both affect the same parts of the brain. Parkinson’s may also have an association with ADHD medications.
Some research also suggests a link between certain stimulants for ADHD treatment and the risk of developing Parkinson’s.
This article looks at the potential link between Parkinson’s and ADHD and what the research says.
Parkinson’s disease is a neurological disorder that
Nerve cells in the basal ganglia usually produce dopamine, a chemical messenger that helps support important bodily functions, including movement.
Parkinson’s disease occurs when these nerve cells become impaired or die, resulting in insufficient dopamine production. This causes the movement changes that occur in people with Parkinson’s disease.
ADHD is a chronic condition that causes inattention, hyperactivity, and impulsive behaviors. Healthcare professionals usually diagnose ADHD in school-aged children.
Experts are not sure of the cause of ADHD, but it may involve genetics and differences in brain anatomy. Environmental factors, such as exposure to toxins during pregnancy, may also contribute.
Researchers are now suggesting a possible link between Parkinson’s and ADHD. According to the Parkinson’s Foundation, this link may be due to the areas of the brain that the conditions affect.
These two areas of the brain — the basal ganglia and the cerebellum — both require healthy amounts of dopamine to function properly.
The basal ganglia refer to a collection of nerve cells that work as messengers between the brain and the nervous system, providing information to the spinal cord and cerebellum. The basal ganglia help control motor functions, behaviors, and emotions.
The cerebellum sends messages to the muscles to help control posture and movements such as walking, as well as coordination, reflexes, and head and eye movement.
Research has shown that people with ADHD have damage to the nerve cells that produce dopamine in the basal ganglia, as well as abnormal cerebellar differences.
Damage to nerve cells in the basal ganglia and changes in dopamine production, as well as cerebellar involvement, also occur with Parkinson’s.
Factors that contribute to this association may include the neurotoxic effects of stimulant medications, environmental factors, and Lewy bodies, which are deposits of protein in the brain.
The researchers had access to statewide medical records from across Utah from 1996–2016. These records belonged to 31,769 people with an ADHD diagnosis and 158,790 people without. The participants had no diagnoses of Parkinson’s or similar diseases and no history of substance misuse.
The results of the
In 4,960 people with ADHD taking prescription psychostimulants, the risk of BG&C diseases was 8.6-fold among those between the ages of 21 and 49 years.
The incidence rate of BG&C diseases was 0.19% for participants without ADHD and 0.52% for participants with the condition. On average, the onset of BG&C diseases occurred at a slightly younger age in the latter group.
People with ADHD had a 2.6-fold increased risk of Parkinson’s compared with people without ADHD.
In people with ADHD taking prescription medication for ADHD, there was a 4-fold increased risk of Parkinson’s compared with the participants without ADHD.
What the results mean
The results from the above study show an increased risk of BG&C diseases in those with ADHD. This means that people with ADHD may be more likely to develop diseases such as Parkinson’s than those without ADHD.
The results also demonstrate that taking prescription stimulants for ADHD may further increase a person’s risk of developing diseases such as Parkinson’s.
However, the authors note that this result could be because people who use medications have a more severe form of ADHD. Therefore, the increased risk could be due to the severity of the condition rather than a direct result of medication use.
According to the study, having ADHD may also increase the risk of earlier onset BG&C diseases, particularly in those who take prescription stimulants.
The authors also acknowledge that other factors that they did not take into account, such as brain injuries, head trauma, and environmental toxins, may play a role in the development of ADHD and Parkinson’s.
About 10–15% of Parkinson’s cases are due to genetics. Environmental factors can also play a part in the development of Parkinson’s. Avoiding risk factors for Parkinson’s, where possible, may help lower the risk.
Risk factors for Parkinson’s include:
- traumatic brain injury
- exposure to certain metals and pesticides
- exposure to trichloroethylene and polychlorinated biphenyls
In people with Parkinson’s, higher levels of physical activity may slow down the progression of motor and non-motor symptoms.
A 2020 review notes that aerobic exercise, in particular, may have protective effects against Parkinson’s. The research also suggests that a balanced diet, such as the Mediterranean diet, may have protective effects. This dietary approach focuses on:
People may find the following organizations and resources helpful for ADHD support:
People with Parkinson’s disease may find the following organizations and resources helpful:
This section answers some common questions about Parkinson’s disease and ADHD.
Do ADHD medications cause Parkinson’s?
So far, there is not enough research to reach a definite conclusion, and the increased risk of developing Parkinson’s is small.
It is important that people with concerns about ADHD medications and Parkinson’s discuss them with a doctor.
Can stimulants prevent Parkinson’s?
According to a
Research suggests that methylphenidates are relatively safe in comparison with amphetamines and may improve motor and non-motor symptoms in people with Parkinson’s.
However, stimulant use cannot prevent Parkinson’s from developing. Chronic use of amphetamines may increase the risk of developing Parkinson’s.
Is there a link between ADHD and dementia?
ADHD may also link to risk factors for dementia, such as low educational attainment, metabolic syndrome, sleep disorders, head injuries, and psychiatric disorders.
After taking into account any psychiatric disorders, the risk of dementia in relation to ADHD was lower. Other risk factors, such as those above, had a limited effect on dementia risk.
ADHD and Parkinson’s both affect the basal ganglia and cerebellum, which are parts of the brain that are involved in movement and require healthy levels of dopamine to function properly.
Research suggests that ADHD — particularly the use of certain ADHD stimulants — may increase the risk of Parkinson’s.
Researchers still need further evidence to determine the link between Parkinson’s and ADHD, as well as the long-term effects of ADHD medications.