Parkinson's symptoms or depression? Look for clinical signs

Many depressive symptoms are seen in the normal course of Parkinson’s disease (PD). As a result, depression—the most common neuropsychiatric disturbance in PD—is difficult to assess in PD and easily can go undetected and untreated.

Making the diagnosis is important, however, because depression causes PD patients suffering and may accelerate decline in motor and cognitive function, activities of daily living, and quality of life. In the absence of specific guidelines, we provide evidence to help you sort through the overlapping symptoms to find clinical signs that differentiate depression from PD symptoms.

Symptoms of depression that occur in or mimic those in the natural course of PD

Psychomotor retardation (bradykinesia)
Depressed or emotionless appearance (‘masked facies,’ stooped posture)
Agitation (dyskinesias)
Decreased interest and enjoyment (apathy and decreased initiative)
Impaired memory and concentration
Fatigue or decreased energy
Impaired sleep
Weight and appetite changes
Physical complaints

Frequency of depressive symptoms in Parkinson’s disease

Effect
Significantly higher frequency in PD patients with depression

Symptoms
Worrying, brooding, loss of interest, hopelessness, suicidal tendencies, social withdrawal, self-depreciation, ideas of reference, anxiety symptoms, loss of appetite, initial and middle insomnia, loss of libido

Effect
No significant differences in frequency compared with PD patients without depression

Symptoms
Anergia, motor retardation, early morning awakening

Recommendations

As we have seen, depression’s somatic and cognitive symptoms and PD’s motor, somatic, and cognitive features overlap substantially. How, then, should clinicians handle symptoms that can be attributed to either depression or PD? Several approaches are possible and each has strengths and weaknesses.

An exclusionary approach may be indicated for research, whereas an inclusive approach may be better suited to clinical settings. As mentioned, the National Institute of Neurological Disorders and Stroke/National Institute of Mental Health Work Group on Depression in Parkinson’s Disease supports an inclusive approach when evaluating depression symptoms. This group also recommends eliminating the DSM-IV-TR general exclusion criterion “due to the effects of a medical condition” applied to the diagnosis of depression.