Psychiatric and Cognitive Disorders in Parkinson’s Disease

Depression and anxiety are so prevalent in Parkinson’s disease and related disorders (e.g., progressive supranuclear palsy, multiple system atrophy, corticobasal ganglionic disease) that most patients will experience an episode of depression or anxiety (usually both) at some time during the course of their disease. Because depression and anxiety are underdiagnosed and undertreated, many patients will suffer chronic depression and anxiety, which may exacerbate disease-associated cognitive impairment and further impair their capacity for self-sufficient living.

After years of increasing doses of direct and indirect dopamine agonists, many patients with Parkinson’s disease develop hallucinations and delusions in addition to the well-known neurological phenomena such as on-off effects, dyskinesias, and abnormal involuntary movements.

With an unstated goal of improving the treatment of cognitive and psychiatric disturbances in Parkinson’s disease, the authors aim their short volume “at senior clinicians and trainees in internal medicine and general practice, at neurologists who may want a better understanding of their patients’ ‘nonmotor’ problems, and at geriatric psychiatrists who may want to access the relevant information about emotion and cognition in Parkinson’s disease, and update their knowledge about the motor complications and treatment of this disorder.”

To educate this somewhat diverse audience the authors have organized the text into seven chapters: clinical, epidemiologic, and therapeutic aspects of Parkinson’s disease; other disorders that can produce parkinsonism and hence mimic Parkinson’s disease in some ways; cognitive deficits in Parkinson’s disease in comparison with other neurodegenerative diseases; depression in Parkinson’s disease; anxiety, phobias, and apathy in Parkinson’s disease; cognitive and psychiatric side effects of antiparkinsonian medications; and treatment of psychiatric disorders in Parkinson’s disease. The book concludes with an appendix in which commonly used neurological and psychiatric rating scales are reproduced verbatim.

In general, the chapters are clearly written and the main points illustrated with well-chosen cases from the authors’ clinical experience. The information is up-to-date, and the reviews are fair and balanced. Points of controversy are clearly indicated. Inclusion of commonly used rating scales will be helpful to readers who do not treat many patients with Parkinson’s disease. I have two minor complaints: 1) In the chapter on parkinsonism the authors briefly mention Pick’s disease, but they do not indicate that Pick’s disease is now regarded as one cause of frontotemporal dementia, which has some cognitive commonalities with Parkinson’s disease and is increasingly recognized as an important type of dementia. 2) The authors briefly describe two nonpharmacological treatments for Parkinson’s disease: pallidotomy and deep brain stimulation. Deep brain stimulation, because it is largely reversible, offers great promise in treating advanced Parkinson’s disease. Potentially, deep brain stimulation can lead to reduction in doses of dopaminergic medications with, one hopes, a concomitant reduction in neurological and psychiatric side effects. Unfortunately (and this is not a criticism of the book), not much has been published on the cognitive and psychiatric effects of the neurosurgical procedures in Parkinson’s disease.

In summary, this will be a valuable book for physicians who want to learn more about Parkinson’s disease and its treatment.