The link between schizophrenia and Parkinson’s idiopathic disease is still unknown and rare where they coexist. So, diagnosis of coexisting schizophrenia and idiopathic Parkinson’s disease is a challenge. It is particularly in developing countries due to a lack of experts and advanced imaging facilities. There are also a few treatment choices. The two disorders have different effects on the brain’s dopamine system. A recent study shows that those with schizophrenia are more likely to experience Parkinson’s later in life.
Parkinson’s disease is a neurodegenerative disorder. This disease causes the brain cells responsible for generating dopamine to eventually die.
The resulting loss of dopamine induces tremors, weakness, extremely slow movements, and poor balance. About 50,000 individuals in the United States got Parkinson last year.
Around half a million people in the U.S. are daily diagnosing with this disease. This number is likely to increase as the population ages. Parkinson’s is more prevalent among older adults.
In the other hand, schizophrenia spectrum disorders are some psychotic conditions. They tend to develop in young people. Scientists believe that an overactive dopamine system in the brain causes them.
This article shows the link between Schizophrenia and Parkinson’s
Key Facts
- A recent study concludes that schizophrenia spectrum symptoms increase the risk of Parkinson’s disease.
- The analysis contained evidence from more than 3,000 people with Parkinson’s disease.
- Researchers got an unexpected result, as symptoms have opposite effects on the brain.
What’s Parkinson’s disease?
Central nervous system dysfunction that causes movement, often including tremor. Nerve cell damage in the brain leads dopamine levels to decrease. This contributes to signs of Parkinson’s disease.
Parkinson’s often begins with a tremor in one hand. Other signs include slow motion, weakness, and loss of balance. Medications help control Parkinson’s symptoms.
You can treat Parkinson’s with a medication called levodopa, which raises the amount of dopamine. But, doctors often manage schizophrenia with medications that block the activity of dopamine.
The opposite effects of these two disorders on the dopamine system have led to a long-standing belief. People with schizophrenia are much less likely to develop Parkinson’s later in life.
A large retrospective analysis by researchers at the University of Turku in Finland and the University of Eastern Finland in Kuopio casts serious doubts on this belief.
The incidence of Parkinson’s disease and schizophrenia in the same individual is rare. Because these disorders have a link with opposite changes in the brain’s dopamine function,” says Dr. Tomi Kuusimäki of the University of Turku, who led the analysis. “Our work changes this prevalent conception.”
What’s the link between Schizophrenia and Parkinson’s?
Also, recent research at the University of Turku, Finland, got some data. It indicates that people with schizophrenia have an elevated risk of Parkinson’s disease later in life. The increased risk could be due to improvements in the brain’s dopamine function.
Furthermore, researchers conducted the record case-control analysis at the University of Turku. The study examines the incidence of previously diagnosed mental illnesses and schizophrenia. They examined more than 25.000 Finnish Parkinson’s disease (PD) patients treated in 1996-2019.
Patients with Parkinson’s disease are previously diagnosed with psychiatric illnesses and schizophrenia more frequently than control patients of the same age.
Previous studies have identified many risk factors for PD. These include age, male sex, insecticide exposure, and head injury. However, the current belief is that PD development is due to a mixture of various environmental, genetic, and patient-specific causes. According to our findings, a previously diagnosed psychotic disorder or schizophrenia could be one factor that raises the risk of PD later in life, says Dr Tomi Kuusimäki of the University of Turku, the main author the research report.
Study changes the idea of the link between Parkinson’s disease and schizophrenia.
PD is currently the fastest-growing neurological disease in the world. It is a neurodegenerative condition most common in people over 60 years of age. Cardinal motor symptoms include shaking, stiffness, and slow movement. Approximately 15,000 patients are currently undergoing PD diagnosis in Finland.
In Parkinson’s disease, the neurons found in the substantia nigra steadily degenerate into the mid-brain. It is due to a deficiency in a neurotransmitter named dopamine. As for schizophrenia, the amount of dopamine rises in certain parts of the brain. Also, PD symptoms can be relieved with dopamine receptor agonists. Schizophrenia is commonly treated with dopamine receptor antagonists.
Regional and national records
The researchers studied the medical history of 3,045 individuals treated for Parkinson’s disease in southwest Finland between 2004 and 2019. 22,189 patients entered the Finnish national registry between 1996 and 2015.
They contrasted the prevalence of pre-existing schizophrenia diagnoses in Parkinson’s patients.
Nationally, the prevalence of schizophrenia spectrum disorders in individuals with Parkinson’s disease was 1.5 percent compared to 1.31 percent among the controls.
Regionally, the prevalence was 0.76% in those with Parkinson’s disease in comparison to 0.16% for the controls.
There are obvious differences in prevalence between national and regional results. But, this indicates that having schizophrenia increases a person’s chance of developing Parkinson’s.
Researchers suggest that increased risk can result from prolonged use of medications. These medications block dopamine receptors, known as dopamine receptor antagonists.
Drugs can change the brain’s dopamine system. It improves a person’s risk of having Parkinson’s disease.
Alternatively, over time, schizophrenia may directly damage the dopamine system. This makes a person more vulnerable to Parkinson’s disease.
We need more studies to investigate whether the severity of psychotic symptoms or the type or dosage of antipsychotic drugs impacts the risk of [Parkinson’s disease], say the researchers in their paper.
Overlapping features
The authors of the report observed that the link between schizophrenia and Parkinson’s is further complicated by the overlapping features of both types of conditions.
In schizophrenia, movement problems are a common side effect of the antidepressant medications.
People with Parkinson’s disease, on the other hand, often develop symptoms of psychosis.
Researchers report that they have tried to avoid confusing these overlapping effects. They used the underlying conditions themselves in their study.
However, they also note:
Advanced [Parkinson’s disease] is often linked with psychotic symptoms. And parkinsonism can be drug-induced in patients with a schizophrenia spectrum disorder. It is, therefore, difficult to distinguish between concurrent [schizophrenia and Parkinson’s] diagnoses in a patient at a certain point in a certain study.
The Bottom Line
Researchers considered the occurrence of Parkinson’s disease and schizophrenia rare in the same person. These diseases are linked with opposite changes in the brain’s dopamine system. But new studies are proving this consideration wrong. We need more research to confirm the link.
