Characteristics of Apathy in Parkinson’s Disease.
Kathy Dujardin, PhD, Pascal Sockeel, PhD, David Devos, MD, PhD, Marie Delliaux, PhD, Pierre Krystkowiak, MD, PhD, Alain Deste´e, MD, PhD, and Luc Defebvre, MD, PhD (2007). Characteristics of Apathy in Parkinson’s Disease. , Movement Disorders, Vol. 22, No. 6, 2007, pp. 778–784.
The authors of this study wanted to look at apathy among people with Parkinson’s disease (PWP). They describe apathy as having reduced participation in tasks that one used to enjoy, difficulty initiating activities, feeling indifferent, and having little expression or feeling “flat.” The authors wanted to evaluate an apathy scale, possibly identify if there is a specific “apathy profile” for PD, as well as to evaluate if depression, cognitive decline, or disease severity affected apathy. Approximately 1/3 of the PWP (none had DBS) in this study were classified as apathetic compared to less than 2% of the non-PD control group. Other research studies have suggested that the range of PWP that have apathy is 16-38%. The apathetic PWP also had more depression and cognitive impairment than the non-apathetic PWP.
One aspect of apathy that was measured revealed that the PWP showed less activity and less initiation than the non-pd group. They also found that PWP who had “fluctuating” motor symptoms or dementia demonstrated a flat affect that was not as evident with the non-PD group or the other PD groups (non-demented, constant motor symptoms). The researchers found that impaired cognitive state was more predictive of apathy than severity of motor dysfunction. The authors readily noted that there are many similar symptoms between depression and apathy but they classify them as distinct entities, which suggests that clinicians and researchers should use appropriate assessment tools to gain a clear understanding of both depression and apathy in PWP.
In the introduction as well as the conclusion of the paper, the authors discuss in detail the role of the frontal lobe (frontal portion in the brain) in apathy and suggest that apathy is not solely related to motor dysfunction and that additional therapies focusing on that area of the brain may improve quality of life in PWP. These authors as well as others discuss the importance of monitoring apathy as well as depression within the PD population, as some studies suggest that both can be a side effect of DBS-STN. It is clear that more research is needed to study both apathy and depression to best treat PWP with and without DBS.