On 2016 Nov 26, David Keller commented:

Thank you. Your findings compare with the CALM-PD study [1], which found "For subjects who consumed >12 ounces of coffee/day, the adjusted hazard ratio for the development of dyskinesia was 0.61 (95% CI, 0.37-1.01) compared with subjects who consumed <4 ounces/day." in patients at an early stage of PD. Longer follow-up should indeed be helpful in assessing whether the benefits of increased caffeine ingestion are durable, at what cost in side-effects, and whether higher doses of caffeine provide correspondingly higher benefits.

Reference

1: Wills AM, Eberly S, Tennis M, Lang AE, Messing S, Togasaki D, Tanner CM, Kamp C, Chen JF, Oakes D, McDermott MP, Schwarzschild MA; Parkinson Study Group. Caffeine consumption and risk of dyskinesia in CALM-PD. Mov Disord. 2013 Mar;28(3):380-3. doi: 10.1002/mds.25319. PubMed PMID: 23339054; PubMed Central PMCID: PMC3608707.

On 2016 Nov 25, Marcello Moccia commented:

We agree with the need for evaluating incidence and severity of dyskinesia in the long-term assessment of drug efficacy in PD. However, studies including de novo PD patients have to consider early markers of motor progression which indeed are associated with the development of dyskinesia in the long term. In view of this, we showed that the voluptuary consumption of caffeine-containing products is associated with reduced need for levo-dopa and with reduced accrual of motor symptoms. Of course, a longer follow-up will possibly confirm the positive impact of caffeine use also on dyskinesia.

On 2016 Nov 09, David Keller commented:

What effect did caffeine consumption have on the incidence or severity of dyskinesia?

In this study, higher caffeine consumption was associated with a lower rate of starting levodopa treatment and reduced motor and non-motor disability. Any treatment for Parkinson disease (PD) which delays or decreases the need for levodopa therapy should be evaluated for its propensity to hasten the onset of dyskinesia, or to worsen established dyskinesia. If the motor and non-motor benefits of caffeine are accompanied by a risk of developing dyskinesia equal to that of a levodopa regimen with equivalent benefits, then it is unclear why ingesting caffeine on a pharmacologic basis is preferable to simply initiating levodopa when it is needed.

On 2016 Nov 09, David Keller commented:

What effect did caffeine consumption have on the incidence or severity of dyskinesia?

In this study, higher caffeine consumption was associated with a lower rate of starting levodopa treatment and reduced motor and non-motor disability. Any treatment for Parkinson disease (PD) which delays or decreases the need for levodopa therapy should be evaluated for its propensity to hasten the onset of dyskinesia, or to worsen established dyskinesia. If the motor and non-motor benefits of caffeine are accompanied by a risk of developing dyskinesia equal to that of a levodopa regimen with equivalent benefits, then it is unclear why ingesting caffeine on a pharmacologic basis is preferable to simply initiating levodopa when it is needed.