Drinking three or four alcoholic drinks a day can double the risk of developing essential tremor – or ‘the shakes’ – in old age, suggest new findings from a Spanish research group. In a report published earlier this year, the same researchers found that individuals with essential tremor were four times more likely to develop Parkinson’s disease than people without the shakes.
Essential tremor is a progressive neurological disorder characterised by uncontrollable shaking of the hands or, in some cases, the head, jaw, face, feet or tongue. An estimated 650,000 people in the UK and five million in the US over the age of 60 are affected by this disorder.
Scientists don’t really know what causes essential tremor. They do know, however, that people with this disorder have damage in the cerebellum part of their brain, including loss of neurons called Purkinje cells. Given that alcohol is known to be toxic to the cerebellum, Louis and colleagues investigated whether alcohol consumption had an effect on the development of essential tremor.
This study assessed lifetime alcohol consumption and neurological symptoms in more than 3,000 people aged 65 years or older. At initial assessment, more than half (1,838 people; 56%) of the participants were found to have had at least one alcoholic drink per day over their lifetime. During the subsequent 3 years, 76 people developed essential tremor.
Individuals who drank 3-4 alcoholic drinks each day were twice as likely to develop essential tremor than those who drank less. In fact, just one or two drinks a day increased the risk by 30%.
The authors suggest that ethanol, a known cerebellar toxin, lowers the threshold for developing ET – a disorder involving the cerebellum. It is also possible that individuals who develop essential tremor use alcohol to self medicate, thus making their shaking worse.
Louis E et al. (2009) Population-based study of baseline ethanol consumption and risk of incident essential tremor. Journal of Neurology, Neurosurgery & Psychiatry 80 (5): 494-497 DOI: 10.1136/jnnp.2008.162701