Parkinson’s anxiety is likely more than plain vanilla
Date: July 15, 2011
Ask most anyone about Parkinson’s disease (PD), and you’ll hear about the motor symptoms: the tremor, the unsteadiness, the freezing in place. Ask psychiatrists, and it’s depression and anxiety that come to mind. The latter disorders are rampant in PD. More than half of patients report depression. Some 40 percent experience anxiety.
But geriatric psychiatrist Gregory Pontone’s focus is even finer. His time as a clinician and as director of Hopkins’ Movement Disorder Psychiatry Clinic has honed his feel for the anxiety that PD patients suffer. And his sense is that it’s more nuanced than most suspect: Subtle but important differences in biology likely separate the anxiety his patients experience from the garden variety, he says.
Depression is common within five years of Parkinson’s onset, “but the anxiety tied to it could occur far earlier,” Pontone says, “as much as 20 years before you see motor symptoms.” And like recent Alzheimer’s studies that now confirm that disease’s long approach, knowing what happens before PD takes hold brings hope of changing its course.
Now Pontone is putting his ideas to the test. As a start, a just-out paper describes an anxiety subtype unique to PD patients. What Parkinson’s patients experience covers a spectrum of anxiety types, often PD-tinged: Some have phobias related to fear of falling, for example, or of “freezing” in the midst of a crowd. Others have anticipatory anxiety tied, say, to facing an upcoming trip. Generalized worry or anxiety attacks—with or without panic—are common.
But “fluctuation-associated anxiety,” Pontone says, “is likely Parkinson’s-unique.” In a cruel irony, it stems from the therapy. Patients typically take levodopa—a drug that boosts much-needed dopamine—and symptoms fade. But after the body metabolizes levodopa they return in force. So patients well into the disease, who need more frequent doses, can ride a roller coaster multiple times a day. And that may bring psychological symptoms ranging from “a sense of discomfort and worry,” Pontone says, “to physical feelings of restlessness and agitation that turn panic-like for some patients. They can last minutes to hours, depending on time until the next dose.”
To help, he and clinic colleagues, including Hopkins neurologists, fine-tune levodopa dosage or add drugs made to pull every shred of benefit from the drug. Then they turn to standard antianxiety agents (except for benzodiazepines, which are risky here). Behavioral therapy is also useful, he says.
But Pontone’s goal is a far earlier approach. Parkinson’s runs a route that begins in the gut, current ideas say, and that spreads to the brain’s motor areas and higher. The movement problems surface with the motor takeover, but earlier stages are supposedly symptom-free. “Many of us, however, think that’s when PD’s psychiatric disorders start,” Pontone says, and he’s singled out panic disturbances, which his work suggests might be a flag.
“That certainly doesn’t mean every middle-aged person with panic gets Parkinson’s!” he says. It could be just that the early disease affects the same fight-or-flight pathways as classic anxiety disorders. “So we need to research those stages more carefully.” Even now, Pontone’s mapping studies to reveal which is which.
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