Depression
in Parkinson's disease (PD) is common, often untreated
and exacerbates motor function problems, suggests a
study published online in Neurology June 20.
It appears depression may simply go unnoticed or get
mistaken for other PD symptoms, the researchers found.
The study suggests better depression treatment would
improve PD patients' overall daily functioning.
UNDER
THE RADAR
The multi-centre study included 413 subjects with early,
untreated PD. "Despite the early course of the PD, clinically
significant depression was still common," says study
author Dr Richard Camicioli, a neurologist at the University
of Alberta. "Almost 30% of patients had symptoms."
Disturbingly, of those, fully 40%
weren't being treated or sent for psychiatric referrals.
There are several possible explanations for this undertreatment.
"Some doctors attribute depressive symptoms, like fatigue
or sleep disturbances, to the Parkinson's itself," says
Dr Camicioli. "This raises the possibility that treatment
ought to be done differently with these patients."
Dr Camicioli and his team also
looked at whether depression was associated with motor
function, the need for symptomatic PD therapies and
level of daily life functioning. They found that depression
was loosely tied to worsened motor skills, but significantly
linked with patients' chances of being prescribed PD
drugs. It also played a role in impaired daily living
activities like eating, dressing and bathing.
PD blues: a chemical connection?
The
causal nature of the link between depression and
PD is poorly understood. One explanation is that
depression is a relatively normal response to
living with a debilitating progressive disease.
But
there may be a more fundamental connection. "Neurochemical
and structural changes in Parkinson's could go
well beyond the dopaminergic system," says Dr
Camicioli. Some experts even wonder whether the
PD etiology in depressed patients may actually
differ from that in non-depressed PD patients.
While he cautions it's speculative to say so,
Dr Camicioli considers it an interesting possibility.
"This research may reveal surprising things. It
could shed light on our understanding of Parkinson's,
and depression too. It's an interesting area to
be working in right now."
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QUALITY
TREATMENT
In cases where depression was recognized, doctors were
often more comfortable treating their patients with
PD drugs than with antidepressants, hoping that mood
improvements will ride the coattails of motor improvements.
But the PD drugs don't always resolve the depression.
"We're not sure that that's the only thing we could
do to improve these patients' quality of life," says
Dr Camicioli.
There's also the possibility that
some antidepressant treatments may worsen PD symptoms.
Little data is available on the effects of antidepressants
specifically in PD patients, so doctors are often reluctant
to prescribe them. "We have much better guidelines on
treating the motor symptoms," says Dr Camicioli.
So what's a doc to do? "Doctors
ought to screen for depression in people with Parkinson's.
The Geriatric Depression Scale is fairly easy to use,"
says Dr Camicioli. "If patients are depressed in our
clinic we assess suicide risk, and initiate antidepressant
treatment. We'll also give a psychiatric referral, or
get patients in touch with support groups or counsellors."
He suggests doctors carefully monitor patients for antidepressant
side effects.
Dr Camicioli hopes his research
can raise awareness of depression in Parkinson's disease.
"Depression is something for family and friends of Parkinson's
patients to really keep an eye open for."
The study hints at new research
horizons. "Being a secondary analysis of trials data,
the study didn't exactly fill a gap, but we definitely
found one." Although he considers the problems caused
by PD's non-motor aspects pressing, Dr Camicioli suspects
interest in cognitive impairments, depression and sleep
issues in PD is growing. "We're realizing how important
this is from a general quality of life perspective,"
says Dr Camicioli.
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