Huntington’s disease is a genetic disorder that generally kicks in between the ages of 35 and 45, causing debilitating dementia and loss of motor control. After the disease was shown to be caused by a lengthy pattern of repeating DNA trios in a gene called Huntingtin, most scientists assumed that the age of onset for neurodegenerative symptoms depended solely on the number of trinucleotide repeats. But a 2004 study analyzing the genetic data of more than 18,000 Huntington’s sufferers from Venezuela found that the age of first disease symptoms was only 40% genetic, and the rest of the disease’s timing was determined by environmental factors. At the time, researchers couldn’t definitively identify any of the environmental factors associated with Huntington’s. But now new research has pinpointed a possible player with addictive implications.
Cecile Duru, a neurobiologist at Amiens University Hospital in France wondered whether chemicals that engage certain neurotransmitter receptors that are altered early on during Huntington’s progression could affect the onset of Huntington’s, and she leaned towards adenosine, which has a pretty common antagonist: caffeine. In research presented at the International Congress of Parkinson’s Disease and Movement Disorders meeting in Toronto today, Duru compared caffeine consumption with age of onset in 80 people with Huntington’s disease, and found that those who consumed over 185 milligrams of caffeine each day — roughly equivalent to two cups of coffee — in the decade prior to disease onset developed neurodegenerative symptoms four years earlier than those who consumed fewer cups of joe.
If these results hold true, caffeine would be the first specific environmental factor identified that can affect the onset of Huntington’s disease. Consequently, stimulating the adenosine receptor — rather than blocking it, as caffeine does — could provide a new therapeutic approach to delaying the effects of Huntington’s.
But surprisingly, these results run counter to those seen with other neurodegenerative diseases in which coffee has been shown to prevent cognitive decline. For example, a recent meta-analysis of five studies looking at the effects of coffee and tea in people with dementia and Alzheimer’s found a beneficial effect of caffeine in three of the reports. And researchers have also shown in animal models of these diseases that blocking the adenosine receptor with caffeine or other drugs prevents neuronal cell death.
So for people with undiagnosed neurodegenerative disease, it seems, it’s still unclear whether the best or worst part of waking up is Folgers in your cup.
Image: Flickr user chichachaunder Creative Commons