June 27, 2007 — Coffee drinking, but not cigarette smoking, may have a protective effect in primary late-onset blepharospasm, a rare type of dystonia.
Investigators at the University of Bari in Italy found individuals who drank 1 to 2 cups of coffee per day were less likely to develop the condition than those who drank less than this amount. Furthermore, there was a delay in the age of onset of the condition associated with coffee consumption — 1.7 years for each additional cup per day.
However, unlike studies of Parkinson's disease, which have linked smoking to a decreased risk for the disease, as well as in a previous study of blepharospasm, the Italian team found no significant protective effect of blepharospasm related to cigarette smoking.
"The protective effect of cigarette smoking and coffee in Parkinson's disease is well established. However, like Parkinson's, blepharospasm arises from the extrapyramidal system. In addition, there is a scarcity of information on the etiology of PD [Parkinson's disease] so we wanted to look at these lifestyle habits to see whether lifetime coffee and cigarette used influenced blepharospasm risk," principal investigator Giovanni Defazio, MD, of the University of Bari told Medscape.
The study is published in the June 19 Online First issue of the Journal of Neurology, Neurosurgery, and Psychiatry.
Smoking Conferred No Protective Effect
In this retrospective, case-control, multicenter study, the 2 lifestyle habits, coffee drinking and cigarette smoking, were examined in 166 patients with primary late-onset blepharospasm, 187 healthy population control subjects (patients' relatives), and 228 hospital control patients with primary hemifacial spasm all from 5 hospital-based movement disorder clinics in Italy.
The lifetime coffee consumption and smoking habits were determined for all participants by an expert interviewer who was not blinded to the case/control status but was unaware of the study hypothesis. All study subjects were asked about their coffee and smoking habits up to the reference age. This was the age of onset of dystonia or hemifacial spasm for case patients and hospital control patients.
A reference age was calculated for the population control subjects based on the duration of the spasms in the hospital control patients.
Study participants were also asked to estimate how many cups of coffee they drank and/or packs of cigarettes they smoked per day. Demographic and clinical information was also collected.
The investigators found that individuals with blepharospasm reported a significantly lower mean number of cups of coffee per day than hospital control patients and population control subjects, whereas there was no significant relationship with the amount smoked per day and a reduced risk for blepharospasm.
Delayed Disease Onset
"We found patients with blepharospasm drank coffee less often than controls, which suggests a strong protective effect. The other important result was the observation that for every additional cup of coffee consumed per day there was a delay in the age of onset of blepharospasm. So the higher the number of cups per day, the greater the delay in onset of the disease," he said.
According to Dr. Defazio, prevalence estimates of blepharospasm are uncertain. Available studies, he said, are biased because of a number of methodologic problems and likely provide an underestimation. However, he said, the most relevant research showed a prevalence of about 133 per 1 million population. Dystonia in general, he added, affects approximately 1000 per million population.
The protective effect associated with coffee is most likely caffeine, said Dr. DeFazio.
"The association of caffeine and BSP [blepharospasm] may be biologically plausible given the pro-dopaminergic activity exerted by caffeine through an antagonistic action on adenosine receptors. This has been called into play to explain the observed protective effect on the development of PD," the authors write.
As a result, said Dr. Defazio, adenosine receptor antagonists may effectively alleviate blepharospasm symptoms.
The team's next research steps, said Dr. Defazio, will be to determine whether coffee consumption has any protective effect in other forms of dystonia such as writer's cramp and cervical dystonia, because although these conditions differ in their clinical presentations, it is likely they have a common etiology.
"I believe our data may have implications for the understanding of the etiology and treatment of primary BSP and that future studies seeking additional environmental or genetic factors for dystonia should take the effect of coffee into account," he said.
J Neurol Neurosurg Psychiatry. Published online June 19, 2007.
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