A new study has found a dose-dependent relationship between coffee consumption and reduced severity of tremors in men with Parkinson disease.
A new study has found a dose-dependent relationship between coffee consumption and reduced severity of tremors in men with Parkinson disease (PD).
Previous research has established that coffee is a negative risk factor for PD, a neurodegenerative disorder that produces motor symptoms, including tremor, as well as nonmotor symptoms. Based on mouse models, investigators have hypothesized that the caffeine in coffee offsets the loss of striatal dopamine and dopamine transporter binding sites seen in PD. There have been few studies that assessed how coffee consumption may be linked with the motor symptoms of PD, and they have suggested that coffee consumption has a positive effect.
The current study, published in BMC Neurology, aimed to determine the association between coffee drinking and motor symptoms in patients with newly diagnosed PD based on their gender. From 2011 to 2016, the researchers enrolled patients at the Chonnam National University Hospital outpatient clinic in China whose PD had been diagnosed by an expert in movement disorders but not yet treated. They had access to patients’ clinical history and neurological examination results, and they asked participants about their past and present coffee drinking habits in semistructured interviews.
Of the 284 patients enrolled, 71.83% (n = 204) were categorized as coffee drinkers (based on past or current coffee drinking) while 28.17% (n = 80) were considered non—coffee drinkers. There were several significant demographic differences between the groups, including that coffee drinkers tended to be younger than the non–coffee drinkers (mean [SD] age, 64.57 [9.83] vs 68.79 [8.24]; P = .001) and that the group of coffee drinkers had a higher proportion of men (58.8% vs 33.8%; P <.001).
When comparing the participants’ scores on the motor and activities of daily living (ADL) subscales of the Unified Parkinson’s Disease Rating Scale, coffee drinkers had significantly lower overall motor scores and lower tremor, bradykinesia, and gait and posture scores compared with non—coffee drinkers. When examining the type of tremor, only rest tremors, not action tremors, were significantly associated with coffee drinking. This association persisted after adjustment for clinical variables, whereas the other motor scores were no longer significant.
Rest tremor scores were lower in both the male and female subgroups of the coffee drinkers, but when looking for a dose-dependent relationship between coffee and PD symptoms after adjusting for clinical variables, tremor scores were inversely related to the number of cups of coffee per day only in the male subgroup.
The study authors suggested that tremor may be caused by pathophysiological mechanisms that differ from those causing bradykinesia and rigidity, which would help explain why only tremor severity was affected by coffee consumption after adjustment. They called for large prospective studies that could help determine the therapeutic effects of coffee or other adenosine A2A receptor antagonists on symptoms of tremor in patients with PD, as well as studies to elucidate the role of estrogen in modulating the relationship between caffeine and tremor severity in women.
“Further investigations are needed to reveal the exact causal relationship between coffee consumption and tremor in PD patients,” they concluded.
Cho BH, Choi SM, Kim BC. Gender-dependent effect of coffee consumption on tremor severity in de novo Parkinson’s disease. BMC Neurol. 2019;19(1):194. doi: 10.1186/s12883-019-1427-y.