I could discuss direct and indirect mechanisms by which chronic dehydration leads to worsening of these issues, but that's not the point here. It's just a truth, a known relationship.
I'm often surprised that we in the medical community don't bother our patients enough about the importance of hydration and am often surprised at how often I see my patients internally rolling their eyes when I bring it up, as if they don't see where their lack of hydration, chronically usually, can actually increase their risk for stroke. Or they yawn at such advice because they don't feel thirsty and assume they are hydrating "enough." This little entry is not about how much is right for each person, because there are numerous factors involved, but I do see a LARGE number of my patients walking around with chronic dehydration. It's endemic it seems.
I have a rule for my older adults (and frankly middle-aged adults should follow it too), and I got the idea from my mother, where it was known in my youth as the Grape-Juice-Water Rule.
I love grape juice. Even now, when I'm out with friends at a party, if there's the option of a beer or grape juice, I'll be the one sipping on the purple stuff. But grape juice is expensive. And growing up, my mother couldn't afford to supply me with an endless supply of grape juice when I came in from outside sweaty and thirsty. So she gave me a choice: She could either start buying as much of the purple powder stuff (grape drink) or I could follow her Grape-Juice-Water-Rule
THE GRAPE-JUICE-WATER RULE:
When I come in from outside thirsty, I have to first drink a full glass of tap water BEFORE I am allowed to drink an equal-amount glass of grape juice. And then after that I can alternate between water and grape juice, a half-glass at a time. And if she saw that I wasn't seeming to follow such a rule, I would just start seeing the powdered grape drink in the fridge instead of actual juice.So, I have modified the rule for my adults who need to work on their hydration.
Dr. Kirk's COFFEE-WATER-HYDRATION RULE:
You can drink your 8 oz cup of coffee in the morning, BUT you have to FOLLOW it with two 8 oz glasses of water afterward, which both keeps you more hydrated (especially since coffee actually makes people lose more water, as a diuretic), and the water coming afterward helps reduce the teeth staining that comes from wonderful coffee. 
AND
I tried to make the glass of water look more exciting.
