The hallmark of Parkinson’s disease is the accompanying motor symptoms, but the condition can bring other challenges. Among those are nonmotor symptoms, including depression, dementia, and even psychosis.
Dr. Leslie Citrome
The culprit is Lewy bodies, which are also responsible for Lewy body dementia. “What we call Lewy body dementia and Parkinson’s disease are caused by the same pathological process – the formation of Lewy bodies in the brain,” Leslie Citrome, MD, MPH, said in an interview. Dr. Citrome discussed some of the psychiatric comorbidities associated with Parkinson’s disease at a virtual meeting presented by Current Psychiatry and the American Academy of Clinical Psychiatrists.
In fact, the association goes both ways. “Many people with Parkinson’s disease develop a dementia. Many people with Lewy body dementia develop motor symptoms that look just like Parkinson’s disease,” said Dr. Citrome, professor of psychiatry and behavioral sciences at New York Medical College, Valhalla, and president of the American Society for Clinical Psychopharmacology.
The motor symptoms of Parkinson’s disease are generally attributable to loss of striatal dopaminergic neurons, while nonmotor symptoms can be traced to loss of neurons in nondopaminergic regions. Nonmotor symptoms – often including sleep disorders, depression, cognitive changes, and psychosis – may occur before motor symptoms. Other problems may include autonomic dysfunction, such as constipation, sexual dysfunction, sweating, or urinary retention.
Patients might not be aware that nonmotor symptoms can occur with Parkinson’s disease and may not even consider mentioning mood changes or hallucinations to their neurologist. Family members may also be unaware.
Sleep problems are common in Parkinson’s disease, including rapid eye-movement sleep behavior disorders, vivid dreams, restless legs syndrome, insomnia, and daytime somnolence. Dopamine agonists may also cause unintended sleep.
Depression is extremely common, affecting up to 90% of Parkinson’s disease patients, and this may be related to dopaminergic losses. Antidepressant medications can worsen Parkinson’s disease symptoms: Tricyclic antidepressants increase risk of adverse events from anticholinergic drugs. Selective serotonin reuptake inhibitors (SSRIs) can exacerbate tremor and may increase risk of serotonin syndrome when combined with MAO‐B inhibitors.
Dr. Citrome was not aware of any antidepressant drugs that have been tested specifically in Parkinson’s disease patients, though “I’d be surprised if there wasn’t,” he said during the Q&A session. “There’s no one perfect antidepressant for people with depression associated with Parkinson’s disease. I would make sure to select one that they would tolerate and be willing to take and that doesn’t interfere with their treatment of their movement disorder, and (I would make sure) that there’s no drug-drug interaction,” he said.
This can include reduced working memory, learning, and planning, and generally does not manifest until at least 1 year after motor symptoms have begun. Rivastigmine is Food and Drug Administration–approved for treatment of cognitive impairment in Parkinson’s disease.
As many as 60% of Parkinson’s disease patients suffer from psychosis at some point, often visual hallucinations or delusions, which can include beliefs of spousal infidelity.
Many clinicians prescribe quetiapine off label, but there are not compelling data to support that it reduces intensity and frequency of hallucinations and delusions, according to Dr. Citrome. However, it is relatively easy to prescribe, requiring no preauthorizations, it is inexpensive, and it may improve sleep.
The FDA approved pimavanserin in 2016 for hallucinations and delusions in Parkinson’s disease, and it doesn’t worsen motor symptoms, Dr. Citrome said. That’s because pimavanserin is a highly selective antagonist of the 5-HT2A receptor, with no effect on dopaminergic, histaminergic, adrenergic, or muscarinic receptors.
The drug improves positive symptoms beginning at days 29 and 43, compared with placebo. An analysis by Dr. Citrome’s group found a number needed to treat (NNT) of 7 to gain a benefit over placebo if the metric is a ≥ 30% reduction in baseline symptom score. The drug had an NNT of 9 to achieve a ≥ 50% reduction, and an NNT of 5 to achieve a score of much improved or very much improved on the Clinical Global Impression–Improvement (CGI-I) scale. In general, an NNT less than 10 suggests that a drug is clinically useful.
In contrast, the number needed to harm (NNH) represents the number of patients who would need to receive a therapy to add one adverse event, compared with placebo. A number greater than 10 indicates that the therapy may be tolerable.
Using various measures, the NNH was well over 10 for pimavanserin. With respect to somnolence, the NNH over placebo was 138, and for a weight gain of 7% or more, the NNH was 594.
Overall, the study found that 4 patients would need to be treated to achieve a benefit over placebo with respect to a ≥ 3–point improvement in the Scale of Positive Symptoms–Parkinson’s Disease (SAPS-PD), while 21 would need to receive the drug to lead to one additional discontinuation because of an adverse event, compared to placebo.
When researchers compared pimavanserin to off-label use of quetiapine, olanzapine, and clozapine, they found a Cohen’s d value of 0.50, which was better than quetiapine and olanzapine, but lower than for clozapine. However, there is no requirement of blood monitoring, and clozapine can potentially worsen motor symptoms.
Dr. Citrome’s presentation should be a reminder to neurologists that psychiatric disorders are an important patient concern, said Henry A. Nasrallah, MD, professor of psychiatry, neurology, and neuroscience at the University of Cincinnati, who moderated the session.
“I think this serves as a model to recognize that many neurological disorders actually present with numerous psychiatric disorders,” Dr. Nasrallah said during the meeting, presented by MedscapeLive. MedscapeLive and this news organization are owned by the same parent company.
Dr. Citrome has consulted for AbbVie, Acadia, Alkermes, Allergan, Angelini, Astellas, Avanir, Axsome, BioXcel, Boehringer-Ingelheim, Cadent Therapeutics, Eisai, Impel, Intra-Cellular, Janssen, Karuna, Lundbeck, Lyndra, MedAvante-ProPhase, Merck, Neurocrine, Noven, Otsuka, Ovid, Relmada, Sage, Sunovion, and Teva. He has been a speaker for most of those companies, and he holds stock in Bristol Myers Squibb, Eli Lilly, J&J, Merck, and Pfizer.
Dr. Nasrallah has consulted for Acadia, Alkermes, Allergan, Boehringer-Ingelheim, Indivior, Intra-Cellular, Janssen, Neurocrine, Otsuka, Sunovion, and Teva. He has served on a speakers bureau for most of those companies, in addition to that of Noven.