That morning cup of coffee can do more than give you a jolt – it can help lower your chances of developing Alzheimer’s. But make sure you drink a dark roast because a new study has found that darker roasts work better as a preventative.

Canada’s Krembil Brain Institute based its research on three types of Arabica coffee – a light roast, dark roast and decaffeinated dark roast.

And although other studies have found health benefits in coffee, this study surprisingly found that dark roasts help lower your chances of developing both Alzheimer’s and Parkinson’s diseases, and that both caffeinated and decaffeinated roasts were effective.

Phenylindanes is the key compound in coffee that had an anti-clumping effect on protein fragments beta amyloid and tau. The clumping of those elements is a key cause of Parkinson’s and Alzheimer’s, experts believe.

Phenylindane is formed during the roasting of coffee beans and higher quantities are found in darker roasts, according to the study, which was published in “Frontiers in Neuroscience.”