BARI, Italy, June 21 -- Coffee drinkers with a multi-cup a day habit are at lower-risk for potentially disabling eyelid spasms than non-drinkers, but cigarette smoking was not protective, as earlier evidence suggested.
In a study comparing 166 patients who developed late-onset blepharospasm with 228 patients who had other forms of facial spasms and with 187 healthy controls, a history of coffee drinking was associated with about a 40% lower risk for eyelid spasms, reported Giovanni Defazio, M.D., and colleagues, of the University of Bari here.
The effect of coffee appeared to be dose dependent, with patients who reported drinking two or more cups a day having the greatest benefit, the authors reported in an early online release from the Journal of Neurology, Neurosurgery & Psychiatry, a BMJ specialty journal.
Patients with a heavy coffee habit also tended to have later onset of spasms, with each additional cup per day delaying onset by 1.7 years (adjusted regression coefficient 1.73; P=0.001), the investigators found.
Although copious coffee-drinking is usually associated with the jitters, the calming effect on eyelid spasms may be related to caffeine, the authors suggested, adding that they were not able to compare caffeinated coffee with decaf, owing to the infrequent use of the latter in Italy.
In an earlier study, the same group had found evidence that cigarette smoking might have a protective effect against late-onset dystonia. However, "owing to multiple testing, this study was liable to a higher risk of false results than ad hoc hypothesis testing studies," the authors wrote.
"In addition, the study did not examine some potential confounders, including coffee. We therefore designed an ad hoc case control study investigating the role of lifetime coffee and cigarette habits on the risk of primary blepharospasm."
The authors looked at information on age at disease onset, smoking and coffee drinking status at the reference age, and the average number of cups of coffee drunk and/or cigarettes smoked per day.
They found that in an unadjusted logistic regression analysis, both coffee drinking and cigarette smoking were inversely associated with blepharospasm risk compared with patients with other types of facial spasms or controls.
But in an analysis adjusted for age, gender, referral center, disease duration, years of schooling, and ever coffee drinking/cigarette smoking, the authors found that smoking was no longer significantly associated with a lower risk for blepharospasm, whereas coffee-drinking remained significant.
In the adjusted analysis, the odds ratio for coffee consumption in cases versus hospital controls was 0.37 (95% confidence interval 0.20 to 0.67) and compared with population-based controls the odds ratio for coffee consumption was 0.44 (95% CI 0.23 to 0.85).
They noted that the evidence for coffee's protective effects against blepharospasm are supported by their observation of a dose-response effect, and delayed onset of spasm among patients with a multi-cup per day habit.
"Several studies have shown a similar dose-related protective effect of coffee in Parkinson's disease," they wrote. "Considering that the caffeine content of a cup of Italian coffee (60-120 mg) is similar to the average content of a cup of American coffee (95-125 mg), the protective effect on the development of blepharospasm might be exerted at caffeine doses greater than 120-240 mg, comparable with the caffeine doses suggested to be protective in Parkinson's disease."
They acknowledged that the study was limited by the retrospective case control design, which may be subject to recall or reporting bias.
The study was supported by a 40% grant from the Italian Ministry for Education, University and Research. The authors declared that they had no competing interests. Primary source: Journal of Neurology, Neurosurgery & PsychiatrySource reference: Defazio G et al. "Influence of coffee drinking and cigarette smoking on the risk of primary late onset blepharospasm: evidence from a multicenter case control study."
J Neurol Neurosurg Psychiatry doi: 10.1136/jnnp.2007.119891
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