In 2012, Canadian researchers brought some welcome news for patients with Parkinson's disease: caffeine may ease symptoms of the disease. But 5 years on, the research team has revealed that the coffee compound may not be so beneficial after all.
The disappointing findings come from a new analysis of more than 120 older adults with Parkinson's disease.
Compared with participants who were given a placebo, subjects who consumed caffeine in doses equivalent to around three cups of coffee per day showed no improvements in movement symptoms or quality of life after 6 to 18 months of follow-up.
Dr. Ronald B. Postuma, of McGill University in Canada, and colleagues recently reported their results in the journal Neurology.
According to The Parkinson's Disease Foundation, up to 1 million people in the United States are living with Parkinson's disease, which is a chronic, progressive central nervous system disorder affecting movement.
While the symptoms of Parkinson's can be different for each individual, tremors, slowness of movement, or bradykinesia, and muscle rigidity are common.
There is currently no cure for Parkinson's disease, but there are medications available that can help patients to manage their symptoms.
From the results of their previous study - published in August 2012 - Dr. Postuma and colleagues believed that they may have identified another promising treatment strategy for patients with Parkinson's, after finding that 6 weeks of caffeine supplementation led to improvements in movement in patients with the disease.
Their latest study looked at the longer-term effects of caffeine supplementation, but it was unable to find any benefits for patients with Parkinson's.
Caffeine did not improve movement
The new research included 121 adults aged 62 years, on average. All patients had been diagnosed with Parkinson's disease at least 4 years prior, and they were followed-up for between 6 and 18 months.
Half of the subjects were given 200 milligrams of caffeine twice daily - which is the equivalent to around three cups of coffee each day - while the remaining participants were given a placebo.
The researchers note that the caffeine-consuming participants began with a placebo and gradually increased their caffeine dose over the first 9 weeks, reaching 200 milligrams twice daily at week 9. This was to help them adjust to the caffeine.
Upon assessing the movement symptoms and quality of life of the participants, the researchers were unable to identify any differences between subjects who took caffeine and those who took the placebo.
"While our previous study showed possible improvement in symptoms, that study was shorter, so it's possible that caffeine may have a short-term benefit that quickly dissipates," notes Dr. Postuma.
"Regardless, our core finding is that caffeine cannot be recommended as therapy for movement symptoms of Parkinson's disease."
Dr. Ronald B. Postuma
The team notes that the current study has some limitations. For example, they say that it is possible that some subjects did not meet the study requirements, and they did not measure blood caffeine levels to help account for this fact.
What is more, the reaserchers say that the caffeine dose of 200 milligrams twice daily was chosen based upon doses used in previous studies, and that higher doses could pose different outcomes.
Still, the current evidence indicates that for patients with Parkinson's disease, that cup of joe is unlikely to offer any benefits for movement.