Previously, addressing motor symptoms of Parkinson’s disease (PD) predominated research. In the past five years, researchers turned to non-motor symptoms as a large unmet need in PD. Shulman and colleagues found 88% of patients had at least one non-motor symptom—see: Shulman LM, Taback RL, Bean J, Weiner WJ, "Comorbidity of the nonmotor symptoms of Parkinson’s disease," Mov Disord, 16:507–510 (2001). Further, prevalence estimates of depression (20-70%), psychosis (10-50%), and dementia (as high as 70%), demonstrate their impact on PD patients and care.

“People often discount Parkinson's Disease as a normal consequence of aging or consisting only of tremor. This work highlights the neurobehavioural problems these patients and caregivers face.”

The article is a systematic review of the evidence regarding the detection and treatment of depression, psychosis, and dementia in PD.

Our work gives clinicians tools to detect behavioral problems in PD (depression, psychosis and dementia). We sought tools that were practical for use in a clinician’s office. Our review also provides evidence for the best treatments for depression, psychosis, and dementia, highlighting areas where information is lacking, in order to help with treatment decisions.

Producing evidence-based practice parameters (practice guidelines) is an important activity of the American Academy of Neurology, both as a service to its members and also to improve the care of people with neurologic illness. It allows the clinician to see the conclusions and recommendations after an intensive, rigorous, highly vetted review of all relevant research in the area.

In this review, scientific evidence, not individual or group opinions, form the basis of its conclusions and recommendations. Due to the rigorous process of investigation, these guidelines are highly regarded, both in guideline methodology and in neurology practice.

As a movement disorders specialist, I am interested in the neurobehavioral aspects of PD, which are under-recognized, yet highly prevalent. Addressing these problems and informing patients has a huge impact on patient and caregiver quality of life. Also, the behavioral changes in PD offer a unique opportunity to understand behavior in non-Parkinson’s patients.

Research directed to detect and treat these problems is needed. As outlined in the "Future Research Recommendations," there is much opportunity to further knowledge and improve patient quality of life.

The research recommendations we made were as follows:

Future research is required to determine the best (sensitive, specific, but also practical for clinicians to rapidly administer) depression screening tool for patients with PD. DSM-IV criteria have not been validated for depression in PD.

Psychosis screening tools: The Parkinson Psychosis Rating Scale needs to be evaluated in nonpsychotic and psychotic PD patients. DSM-IV criteria for psychosis have not been validated in PD and this is required to further research in psychosis and PD.

Cognition screening tools: Screening tools must be easy and quick to administer. Cognitive decline in PD is characterized by impaired executive function, visuospatial abnormalities, impaired memory, and language deficits. An appropriate scale that reliably incorporates executive function (e.g., frontal assessment battery and other practical tests of executive function) should be incorporated into a screening test for PD dementia. When evaluating new screening tools, the DSM-IV criteria for dementia may not be the most appropriate gold standard for patients with PD. DSM-IV criteria for dementia have not been validated in PD. In PD patients, it may be difficult to assess impairments in domains other than memory.

Depression treatment: There is a need for randomized, double-blinded, placebo-controlled studies of adequate size and duration of follow-up to assess antidepressants, psychotherapies, and other somatic therapies such as electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS).

Psychosis treatment: Due to rare but possible agranulocytosis—a condition which occurs when a person does not have enough white blood cells called granulocytes—and concerns about increased mortality associated with clozapine, other treatments should be identified for patients with PD and psychosis. Class I studies are required to evaluate the efficacy of quetiapine. Evidence for efficacy of novel antipsychotics without dopaminergic blocking effects is needed for effective treatment of psychosis in PD.

Dementia treatment: The cognitive benefits of donepezil and rivastigmine were small in PD dementia or DLB, and tremor increased with rivastigmine. Therefore, future research should include more Class I studies to assess the role of cholinesterase inhibitors and other medications in the treatment of dementia associated with PD. Additional treatments need to be developed that alleviate cognitive symptoms without worsening parkinsonism.

The increased attention on these problems for people with PD is important to convey the impact this illness has. People often discount PD as a normal consequence of aging or consisting only of tremor. This work highlights the neurobehavioral problems these patients and caregivers face. Neurobehavioral complications of PD are in fact, the commonest reason for nursing home placement—PD alone estimated to comprise more than 10% of nursing home admissions.

Thus, improving our detection and treatment of these problems will have major healthcare utilization implications. The current prevalence of PD in the United States alone is 1,000,000 people. Since the prevalence of PD increases with age, our aging population will experience more of these problems. Research to address these problems will result in healthcare savings and improve the quality of life of countless patients and their families.