According to researchers in the U.S. people suffering from Parkinson's disease can be apathetic without being depressed, and apathy may be a core feature of the disease.
Apathy is a mental state characterized by a loss of motivation, loss of interest, and loss of effortful behavior.
In apathy, a person's mood is neutral and there is a sense of indifference, whereas in depression, the mood is negative and there is emotional suffering.
However because apathy and depression share some of the same symptoms, the disorders can be misdiagnosed.
Dr. Lindsey Kirsch-Darrow from the University of Florida in Gainesville believes it is important to screen for both apathy and depression so patients can be treated appropriately.
She also says it is important that family members and caregivers understand that apathy is a characteristic of Parkinson's disease and is not laziness or something the patient can voluntarily control; it is a symptom of Parkinson's disease.
Kirsch-Darrow and colleagues compared 80 patients with Parkinson's disease to 20 patients with dystonia, another movement disorder and they found a "significantly higher severity and frequency of apathy" in the Parkinson's disease patients compared to the dystonia patients.
It seems 51% of Parkinson's disease patients exhibited apathy compared with 20% of those with dystonia.
The researchers say that apathy without depression was common in Parkinson's disease patients but was not seen in any of the dystonia patients.
For patients with apathy, stimulant-type drugs have been suggested as a possible treatment, but experts suggest that the current criteria for diagnosing depression may not be appropriate for people with Parkinson disease.
With apathy it is appears it is usually a family member who complains because the patient requires constant prompting to do anything and does not want to go anywhere and not the patient themselves complaining.