Is There a Link Between Sleep Disorders and Personality in Parkinson's Disease?

What you need to know

• People with Parkinson’s disease and a sleep disorder called REM sleep behavior disorder (RBD) have high rates of obsessive-compulsive personality traits.
• Over half of RBD patients and nearly half of Parkinson’s patients showed signs of obsessive-compulsive personality disorder, compared to only 13% of healthy controls.
• This suggests there may be a common personality profile associated with both RBD and Parkinson’s disease, potentially related to changes in brain circuits.

Background on REM Sleep Behavior Disorder and Parkinson’s Disease

REM sleep behavior disorder (RBD) is a sleep condition where people physically act out their dreams. Normally during REM sleep, our bodies are paralyzed to prevent us from moving. But in RBD, this paralysis doesn’t work properly. People with RBD may kick, punch, yell, or jump out of bed while dreaming.

Interestingly, RBD is closely linked to Parkinson’s disease and related brain disorders. Many people who develop RBD go on to be diagnosed with Parkinson’s disease years later. Because of this connection, researchers are very interested in studying people with RBD to better understand the early stages of Parkinson’s disease.

Parkinson’s disease is a brain disorder that causes problems with movement, like tremors, stiffness, and difficulty walking. It also can cause non-movement symptoms like loss of smell, constipation, and sleep problems. Parkinson’s develops when brain cells that produce dopamine die off.

For many years, doctors and researchers have noticed that people with Parkinson’s disease often have certain personality traits, like being very cautious, rigid in their habits, or perfectionistic. However, it hasn’t been clear if these personality traits develop because of Parkinson’s disease or if they may actually be present before the disease begins.

What This Study Looked At

This study aimed to examine personality traits in three groups of people:

1. Patients with REM sleep behavior disorder
2. Patients with Parkinson’s disease
3. Healthy individuals without either condition (the control group)

The researchers wanted to see if there were differences in personality disorders between these groups. In particular, they focused on obsessive-compulsive personality disorder.

People with obsessive-compulsive personality disorder tend to be overly focused on order, perfectionism, and control. They may have very rigid routines or beliefs, be workaholics, or have trouble delegating tasks to others. This is different from obsessive-compulsive disorder (OCD), which involves unwanted intrusive thoughts and repetitive behaviors.

The study included:

• 29 patients with RBD
• 30 patients with Parkinson’s disease
• 30 healthy control subjects

All participants underwent neurological exams and completed questionnaires about their personality traits. They were also interviewed by a neurologist to assess for personality disorders based on standardized diagnostic criteria.

Key Findings

The main findings of the study were:

1. Obsessive-compulsive personality disorder was much more common in both the RBD and Parkinson’s groups compared to healthy controls:

   • 55.2% of RBD patients had obsessive-compulsive personality disorder
   • 46.7% of Parkinson’s patients had obsessive-compulsive personality disorder
   • Only 13.3% of healthy controls had obsessive-compulsive personality disorder

2. The rates of obsessive-compulsive personality disorder were very similar between the RBD and Parkinson’s groups.

3. Other types of personality disorders were much less common in all groups.

4. Statistical analysis showed that having RBD was strongly associated with having obsessive-compulsive personality disorder, even after accounting for factors like age and sex.

What This Means

These results suggest there may be a common personality profile associated with both RBD and Parkinson’s disease. The high rates of obsessive-compulsive traits in both conditions, compared to healthy individuals, points to a potential link.

This is interesting because RBD often develops years before the movement symptoms of Parkinson’s disease appear. Finding similar personality traits in both groups raises the possibility that these traits may be an early sign of brain changes related to Parkinson’s disease.

The researchers propose that the high rates of obsessive-compulsive personality in both RBD and Parkinson’s could be related to changes in brain circuits connecting the frontal lobes and an area called the basal ganglia. These circuits are known to be involved in both Parkinson’s disease and in regulating personality and behavior.

However, it’s important to note that this study only looked at people at one point in time. It can’t tell us whether these personality traits actually develop before RBD or Parkinson’s disease, or if they appear as a result of the conditions. Larger studies that follow people over time will be needed to clarify this.

Limitations of the Study

There are a few limitations to keep in mind when interpreting these results:

1. The study had relatively small numbers of participants in each group. Larger studies will be needed to confirm the findings.

2. Not all of the RBD patients had their diagnosis confirmed with an overnight sleep study. Some were diagnosed based on symptoms and examination by a sleep specialist. This introduces some uncertainty.

3. The study only looked at participants at one point in time. It can’t tell us how personality traits might change over the course of RBD or Parkinson’s disease.

4. The RBD patients were significantly younger on average than the Parkinson’s and control groups. While the researchers tried to account for this statistically, it could still influence the results.

Conclusions

• Obsessive-compulsive personality traits appear to be much more common in people with REM sleep behavior disorder and Parkinson’s disease compared to the general population.
• This raises the possibility that certain personality traits could be an early indicator of brain changes related to Parkinson’s disease, appearing even before movement symptoms.
• More research is needed to understand if these personality traits actually develop before RBD and Parkinson’s disease, or if they appear as a result of the conditions.
• Understanding personality changes associated with RBD and Parkinson’s disease could potentially help with earlier diagnosis and treatment in the future.

While these findings are intriguing, it’s important to remember that having obsessive-compulsive personality traits doesn’t necessarily mean someone will develop RBD or Parkinson’s disease. Many people have some of these traits without ever developing a neurological condition. More research is needed to fully understand the connections between personality, sleep disorders, and Parkinson’s disease.