Depression in Parkinson’s disease patients is a little like the riddle about the chicken and the egg: Which came first — the nervous system disorder characterized by impaired movement and slurred speech, or the depression that is both an early symptom of the disease as well as a consequence of it?

Until a decade or two ago, scientists thought the latter was true, says Michael Okun, a neurologist and co-director of the University of Florida’s Center for Movement Disorders and Neurorestoration. “The prevailing thought was that it was a reactionary thing, like a reaction to a traumatic event,” says Okun, who is also the medical director of the National Parkinson Foundation. “Now we think there are biological changes in the brain that we believe underlie depression.”

In Parkinson’s disease, cells are dying off in certain parts of the brain, creating a deficiency of neurotransmitters that affect our mood. Much of the attention has focused on loss of dopamine, which causes the tremors, slowness and stiffness associated with Parkinson’s. But other neurotransmitters — serotonin and norepinephrine — also undergo “robust degeneration,” Okun says, which is largely responsible for the onset of depression.

Read: [What You Need to Know About Schizophrenia]

Depression as an Early Warning Sign of Parkinson’s

Depression may predate the onset of motor impairment, and in fact be the first sign of Parkinson’s disease, five to 10 years before a Parkinson’s diagnosis. According to Jim Beck, vice president of scientific affairs at the Parkinson’s Disease Foundation, 60 percent of Parkinson’s disease patients suffer from depression, which preceded Parkinson’s disease for 30 percent.

Spotting depression early can be difficult, since the initial symptoms may be subtle and overlap with Parkinson’s itself, Okun says. Typical symptoms of both conditions include loss of energy and interest in things, as well as overall slowness, both in movements and mental response time. The earlier depression is diagnosed, the better, since “the longer you are depressed, the harder it is to reverse it,” says Peter Schmidt, chief information officer at the National Parkinson Foundation. “If left untreated, the brain will adapt to being depressed. The brain is optimized structurally to do the things that you do.”

Depression in Parkinson’s patients is also “the main driver of quality of life,” Schmidt adds. This result emerged from the Parkinson’s Outcome Project, a survey of more than 7,500 Parkinson’s patients in the U.S., Canada, the Netherlands and Israel. In other words, depression was the top criterion for patients evaluating their own health status.

That may be a stunning revelation, considering the focus of doctor’s visits is normally on the physical degeneration associated with Parkinson’s, Okun says. That’s in part because most Parkinson’s disease patients are only ever treated for their condition by their neurologists — after having been diagnosed by their geriatrician or general practitioner. None of these doctors specialize in psychiatric issues, nor would they necessarily think to refer patients to a psychiatrist, Schmidt adds.

Patients treated at places that refer them to mental health professionals, which is the case largely at academic medical centers like the University of Florida, have the lowest rates of depression, according to the Project results, Schmidt says. “A lot of these centers are helping patients early,” Schmidt says.

Read: [Coping With Depression at Work]

Treating Depression and Parkinson’s in Tandem

At UF Health, psychiatrist Herb Ward’s office is down the hall from Okun’s. “We exchange notes on patients,” Ward says. “It’s the best way to do it.”

Ward says he sees patients even more frequently than Okun will, starting with monthly appointments that become quarterly. Ward normally starts treatment plans with antidepressants, which work directly on the neurotransmitters that Parkinson’s depletes. “We can usually choose an agent that is a good fit with the patient,” Ward says, adding that antidepressants’ typical side effects, like weight gain, can actually play in Parkinson’s disease patients’ favor.

“Weight loss is common in Parkinson’s disease, so weight gain can be a good thing,” Ward says, adding that sleep issues are also common. “We can use a sedating antidepressant at night, so the side effect profile isn’t always a negative thing.”

Psychotherapy and cognitive behavioral therapy are also helpful, especially when combined with antidepressants, Ward adds. And for patients who don’t respond to either of these approaches, the more invasive therapies — transcranial magnetic stimulation and electroconvulsive therapy — work well with few side effects, Okun adds.

Read: [How to Find the Best Mental Health Professional for You]

The key for patients and their caregivers, experts say, is to know if patients are at risk of Parkinson’s disease and related depression and to be proactive about handling both.

“If you have a family history [of Parkinson’s disease] and develop depression at an early age, you should be aware of your risk of Parkinson’s disease,” Schmidt says, adding that people with a history of depression are 2.4 times more likely to develop Parkinson’s disease, even though the percentage of people over age 55 with Parkinson’s is still relatively small at 1.5 percent.

But the sheer prevalence of depression in Parkinson’s patients, coupled with neurologists’ natural preoccupation with treating the disease’s physical, rather than psychological, consequences, “puts the onus on patients to be well educated,” Beck says. “Be on the lookout for signs, and speak up to physicians. It’s the kind of conversation that needs to happen.”

And mostly, don’t suffer in silence, he adds. While on a positive note, suicides are rarer among Parkinson’s disease patients than the general population, suicidal thoughts plague many patients chronically. Robin Williams may have been one tragic example of that tendency. He was struggling with the early stages of Parkinson’s, which may have exacerbated his struggles with depression. For most Parkinson’s patients, however, suicide is not the outcome because the very loss of energy and apathy associated with the disease (symptoms overlapping with depression) are what actually prevent patients from going through with it, Beck says.

“That may be a silver lining, but it’s no way to live life,” Beck says.

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Dealing With Parkinson’s Disease-Related Depression originally appeared on usnews.com