Parkinson's Disease: Effect on Learning

Since Parkinson's disease is a neurological disorder, it might be expected that the typical functions of the brain---memory, learning, planning---would be affected. Though Parkinson's disease primarily affects motor functions, patients can experience learning challenges, and in the 10 to 15 percent of patients who develop dementia in later stages, learning can be significantly impaired.

• Learning can be more challenging for Parkinson's patients.

Basics

• Parkinson's is a progressive degenerative disease in which motor functions (the ability to initiate, inhibit and direct movement) is impaired. Although the cause of Parkinson's is unknown, the reason it occurs is the lack of an essential chemical messenger in the brain known as dopamine. If dopamine is not present in large enough quantities or the brain is unable to process the amount of dopamine there is, movement begins to decline, become disrupted or cease altogether. Inadequate dopamine levels can also affect learning, especially reward-based learning.

Learning

• Learning relies on several things, including short-term memory, sensory processing, long-term memory, the ability to make connections between concepts and the ability to categorize. The entire brain is activated during learning, but the structures that process memory are critical. Repeated behaviors, or practice, increase the number and strength of connections within the brain and lead to more effective learning.

  Reward and punishment for a certain action or thought can strengthen, weaken or eliminate the behavior. In other words, you learn to do or not do something based on what happens after you do it. Parkinson's patients may experience learning differently because of the way their brain approaches learning, the effects of practice, and how they respond to reward and punishment.

Brain Use

• Though Parkinson's patients are able to learn new skills and concepts, a University of Montreal study discovered that people with Parkinson's diseases work harder at learning than people without Parkinson's.

  The structures in the brain that control memory are more active in someone with Parkinson's, using direct access to memory to learn rather than the indirect routes "normal" people use. Both groups are able to learn the same task or concept to the same degree. The brains of Parkinson's patients work harder at processing and establishing learning by drawing on more mental systems than people without Parkinson's.

Practice

• A 2002 study cited in the Journal of Neurology, Neurosurgery, and Psychiatry found that though initial learning of a task by Parkinson's patients was impaired compared to a group of "normal" people, a repeated test of the same material resulted in no significant difference between the two groups. This suggests that the old saying, "Practice makes perfect," can be applied to Parkinson's patients.

Reinforcement

• Learning is often accomplished by reacting to a positive reinforcement (a reward such as praise, money or food) or punishment (such as scolding, disapproval or isolation). A Rutgers University study found that Parkinson's patients who were not taking dopamine medication were significantly less likely to learn through positive reinforcement, but they learned at a normal rate with punishment.

  Oddly, once the patients began taking medication, this process reversed. With adequate dopamine, patients learned normally with rewards, but not with punishment. The researchers suggested that this decrease in learning from the negative effects of their behavior, combined with a focus on positive effects, may explain why some treated Parkinson's patients develop reward-based behaviors like compulsive overeating, gambling and hypersexuality.