I found the inital, "diagnostic", treatment with sinemet, alone, to have the most effective anti-depressant activity of any of the several standard ADs I had been prescribed in the decade of depressive symptoms prior to PD Dx. Admittedly, that could be because my last depressive bout which occurred a year before Dx, was the worst. That, along with the PD symptom relief may have subjectively magnified the percieved effect.
Robert