Regular coffee (slow brewed as with a filter or cafetière) is sometimes combined with espresso to increase either the intensity of the flavour or the caffeine content. This may be called a variety of names, most commonly "red eye," "shot in the dark," and "depth charge" – though this last is a federally registered trademark of a company, Caribou Coffee, so its usage is restricted. Coffeehouse chains may have their own names, such as "turbo" at Dunkin' Donuts. A double shot of espresso in the coffee may be termed a "black eye," and a triple shot a "dead eye." "Caffè Tobio" is a version with an equal amount of coffee to espresso.
Generally the best type of coffee to use in order to make a great tasting cup of black coffee is that which has been freshly ground. The reason why freshly ground is better is because after a couple of days ground coffee generally begins to lose its taste. Also if you are going to make coffee on your stove top then only keep it on there for a few minutes as any longer and the coffee will lose some of its taste and in some cases will become bitter. So it is better if you serve the coffee as soon as you have made it. Also you should use about 2 tablespoons of ground coffee for every cup that you make expect in the case of espresso. If making an espresso it is best to follow the guidelines that your espresso machine will have.
A 28-year study, eventually published in 2017 in Alzheimer's and Dementia, the journal of the Alzheimer's Association, determined that four to five cups of a coffee a day – a level deemed "moderate" – led to a decreased risk of dementia during that time period. Those who drank coffee in moderate levels had less medial temporal atrophy, which is linked to Alzheimer's disease, compared to those who drank three or fewer cups a day, including those who didn't drink any.