People with Parkinson’s disease are more likely to have received an ADHD diagnosis in the past compared with those who don’t have Parkinson’s. Several things may contribute to this link, including genetics.
Attention deficit hyperactivity disorder (ADHD) and Parkinson’s disease are distinct neurological conditions. They typically onset at different life stages: ADHD in childhood and Parkinson’s in older adulthood.
Despite their differences, both conditions involve dysfunctions in the brain’s dopamine system, which regulates movement, mood, and cognition.
Recent research suggests this shared dopamine pathway may link the two conditions, potentially increasing the risk of Parkinson’s disease in those with a history of ADHD.
ADHD does not directly cause Parkinson’s disease, but having ADHD may raise the risk of developing neurological conditions like Parkinson’s.
Both ADHD and Parkinson’s disease share issues with dopamine function in the brain, specifically in the striatum (a key part of the basal ganglia). This may lead to similar challenges in focus, memory, and self-control.
A 2020 study using Taiwanese health data found that individuals with ADHD have a higher risk of developing Parkinson’s disease. Researchers found that people with Parkinson’s were 2.8 times more likely to have a prior ADHD diagnosis than those without Parkinson’s. This connection wasn’t due to other health conditions.
In addition, an animal model of ADHD displayed brain changes similar to those seen in Parkinson’s disease.
The findings suggest that dopamine issues may connect ADHD and Parkinson’s disease, and that people with ADHD might need to be monitored over time for Parkinson’s-like symptoms.
Can Parkinson’s disease cause ADHD?
Parkinson’s disease does not cause ADHD. However, both conditions involve
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They found that certain genetic factors related to brain volume, especially in dopamine-rich regions like the caudate nucleus and putamen, may contribute to both ADHD and Parkinson’s. These regions are critical for movement and cognitive control, which both conditions can impair.
However, a 2020 study found only a very weak, negative association between Parkinson’s and ADHD, meaning their genetic risk factors overlap very little.
Additionally, when researchers tested whether having genes for one condition might increase the risk of the other, results were negative.
ADHD medications, especially stimulants like amphetamines (Adderall) and methylphenidate (Ritalin), have been linked to a higher risk of developing Parkinson’s disease later in life. These medications increase dopamine levels in the brain, which is the same neurotransmitter system affected in Parkinson’s.
Research shows that dopamine transporter levels differ in ADHD and Parkinson’s. People with Parkinson’s disease generally have reduced dopamine transporters, while those with ADHD often have elevated levels.
In the 2020 Taiwanese study mentioned earlier, researchers found that people with ADHD, particularly those taking stimulant medications, had a greater likelihood of developing diseases of the basal ganglia and cerebellum, including Parkinson’s, before age 50 years.
Specifically, people with ADHD who took stimulants had four times the risk of developing Parkinson’s than those without ADHD.
While stimulants are designed to correct dopamine imbalances in ADHD, there’s still uncertainty about whether these medications further exaggerate the differences in dopamine transporter levels between ADHD and Parkinson’s disease. More research is needed to understand this connection fully.
Parkinson’s disease and ADHD are typically treated with different approaches due to the distinct ways these conditions affect the brain, particularly regarding dopamine levels.
Parkinson’s disease treatment
The primary treatment for Parkinson’s focuses on increasing dopamine levels or mimicking dopamine’s effects.
Common approaches include:
- Levodopa: This is the most common and effective medication for Parkinson’s. The brain converts it into dopamine.
- Dopamine agonists: These medications mimic dopamine’s effects directly on the brain.
- MAO-B inhibitors: These prevent the breakdown of dopamine in the brain.
- Deep brain stimulation (DBS): DBS is a surgical option for individuals whose symptoms aren’t controlled by medication.
ADHD treatment
ADHD treatment usually focuses on increasing dopamine and norepinephrine activity in the brain, particularly through stimulant medications:
- Stimulants, such as Ritalin and Adderall: Stimulants increase dopamine levels by blocking its reuptake and stimulating its release.
- Nonstimulants, such as atomoxetine: Nonstimulants affect norepinephrine, which indirectly increases dopamine levels in the brain.
It’s rare for a person to receive a diagnosis of both conditions simultaneously, but it’s possible. Some people with early onset Parkinson’s disease may have had ADHD earlier in life, and the two conditions might overlap in certain cases, especially with the impact of dopamine dysfunction.
In these cases, healthcare professionals need to carefully monitor symptoms and medication effects, often adjusting treatment based on how each condition evolves over time.
Some studies suggest a genetic connection between ADHD and Parkinson’s disease, particularly in brain areas that regulate dopamine. However, while shared genetic factors may play a role, there’s no clear evidence that one condition causes the other.
The differences in dopamine function between ADHD and Parkinson’s disease complicate the relationship. More research is needed to fully understand how these conditions may be linked.