Anyway, ever since my sister-in-law’s mother was taken to the doctor with signs of Alzheimer’s and discovered to have nothing but dehydration, I’ve been meaning to read up on how exactly the lack of water hinders brain function.
Here’s what I found about dehydration and the aging brain:
Not much—unless you count articles on websites trying to sell water filtration systems.
The fact that water makes up 70-80% of a nerve cell and transports both nutrients and wastes from neurons means it is essential for proper brain function all through life. That’s a given. What’s not a given is how much a brain has to be depleted of water to affect cognition.
Rigorous research on the topic of the brain and dehydration is limited. Even the “standard facts” about the body and water are all over the place: babies come out of the womb composed of 90% water; no, 78%; no, make that 70%. In adults, the proportion is 60% water for males and 55% for females. The consensus is 50-60% for adults in general. The brain is 60% water; nay, 90%. Whatever.
As for how much water you need to drink on a daily basis to be properly hydrated, oy, there is no consensus. For years I’ve been hearing “8 cups a day.” No allowance for a sedentary life or for someone with a diet of fruits and vegetables (which are high in water content); no penalty for eating junk food (which would increase the need for the detoxifying properties of water) or for spending days cooped up near a wood stove.
One article quoted the Mayo Clinic as saying that “the average adult loses more than 80 ounces of water every day through sweating, breathing, and eliminating wastes,” and therefore you’d have to drink 10 cups of water/day to rehydrate. I searched for the quote on the Mayo Clinic site and didn’t find it. Instead, I found a recommendation for 6-8 cups of water per day.
Suppose you take the most conservative recommendation of 6 cups per day-do you follow that? I don’t think I’ve ever gone one whole week drinking that much per day.
It has been estimated that 75% of Americans are chronically dehydrated. OK, that figure is questioned. But it seems to be a fairly hard fact that “among people over 65, dehydration is one of the most frequent causes of hospitalization.”* Understandable: throw in a bit of incontinence, and fear of hydration soars. Also, some medications are diuretics, and after 50, the body loses kidney function and is less able to conserve fluids.*
But how bad is dehydration for your brain?
According to Lumosity, when your body lacks water,
brain cells and other neurons shrink and biochemical processes involved in cellular communication slow. A drop of as little as 1 to 2% of fluid levels can result in slower processing speeds, impaired short-term memory, tweaked visual tracking and deficits in attention. With proper hydration however, neurons work best and are capable of reacting faster.
But pinning down the exact link between hydration and cognitive function is tricky in the lab. From Hydration and Human Cognition:
Although adequate hydration is essential for optimal brain function, research addressing relationships between hydration status and human behavior and cognitive function is limited. The few published studies in this area are inconclusive and contradictory. The impact of variations in hydration status, which can be substantial as humans go about their daily activities, on brain function and behavior is not known and may impact quality of life.
From PubMed’s Hydration and Cognition: a Critical Review and Recommendations for Future Research: “The limited literature on the effects of dehydration on human cognitive function is contradictory and inconsistent.” The monkey wrench in research here is given as confounding factors:
Confounding factors, such as caffeine intake and the methods used to produce dehydration, need to be considered in the design and conduct of such studies. Inclusion of a positive control condition, such as alcohol intake, a hypnotic drug, or other treatments known to produce adverse changes in cognitive performance should be included in such studies. To the extent possible, efforts to blind both volunteers and investigators should be an important consideration in study design.
On the Mayo Clinic site, a Dr. Lette finds that “there’s no scientific evidence that drinking large amounts of water is good for one’s health.” The recommendation in this article is to drink when you’re thirsty, and that’s enough.
My question is, does the lack of scientific evidence mean there is no scientific proof or merely that there is no motivation to research the topic to obtain the evidencef? Who, after all, would fund research into water being fundamental to the health of the aging brain? Not the pharmaceutical industry. If you could avoid dementia by being continually hydrated, you wouldn’t need pills to fix dementia. Why would any self-respecting drug company fund that finding? And if it takes a lot of money to work through all the confounding factors, who’s going to pay for it?
The thing is, when the anecdote about my sister-in-law’s mother is not even rare, it makes me wonder how many cases of Alzheimer’s are checked for a history of dehydration. I don’t mean just the over-the-weekend kind of dehydration, but long-term, chronic shortage of water.
As with Mom. The list of things Mom was doing “right” for her aging brain is stellar: she was highly educated, spoke multiple languages, was given to prayer and meditation, was active in the community, etc., etc. Yet she succumbed to complete dementia in her early seventies! Could it all have been due to her severe distaste for water? I mean, she hated water-would gag if she drank it straight from the tap. Could her present dementia have been prevented by a regimen of 4+ cups of plain ole water daily?
I hate to look at the “what if” from Mom’s point of view, but for our generation and beyond, it needs a good deal more consideration than we’re giving it.
What do you think? Am I grasping at straws? (I suppose that’s OK as long as the straw is propped inside a nice glass of water, right?).
Resources:
Water and Brain Function
Water in the Body”
You’re Not Demented, Just Dehydrated
Dehydration and Cognitive Performance
Hydration and Cognitive Function in Children
Nerve and Muscle Cells
Impaired cognitive function and mental performance in mild dehydration
Excellent Article.
I was taken to the hospital a few years ago, unsteady on my feet, dizzy, couldn’t think straight. Thought I was having a stroke. After blood work was taken it turned out I had low electrolytes. When I was asked how much water I had to drink I said, “I drink a lot during the day because I take a diuretic.” The ER nurse said, “Too much water is not good unless you’re getting the minerals needed.” I apparently had diluted my minerals. Sodium plays a part in brain health. There’s dehydration, and there’s too much hydration.Till this day I find that interesting.
Also my grandfather who lived to be 98 years old, no dementia, spoke English and Italian, walked everyday, drank ‘wine’ everyday did not drink water. When he visited us he’s say, “RoseMarie give me a drink.” I filled a glass of water and gave it to him. “What do you want to do rust my pipes,” he said in broken English. So I do wonder if water is the answer to good brain health. Hope this gave you a laugh, true story though.
Those are good stories, Rose. I’m glad you added that you can be over-hydrated as well as dehydrated. In fact, hyper-hydration can kill you. Good thing you got that under control. Go figure, right?
Then your grandpa goes and throws a curve to the curve. Confounding factors!
Very good to bring dehydration topic and elderly together. Dehydration is a very big problem in nursing homes causing more confusion, urinary tract infections etc. I know a literally had to gentle hold the glass of water to my mothers mouth to get her to drink. She always insisted she was not thirsty. It took me quite a while to figure out she did not experience thirst as you or I do. I also think she still understood the drink meant pee, and that was a chore for her. First off, she had to find the bathroom. She lived in my house for almost 2 years and never could remember where the bathroom was but she could sense when I was in a bad mood. Strange disease that Alzheimers. As we all know a caregiver could not make up stuff as baffling as the reality.
There is a new article on the New York Times site today that might interest you. Thanks again for the excellent blog. Sorry I didn’t see an email to send this rather than the comment section.
http://www.nytimes.com/2012/03/06/science/a-quest-to-understand-how-memory-works.html?hpw
Hey Marty,
Thanks for the info and the great job you are doing with this site! Love the Jabberwocky poem, and am determined to try it out with my friends who seem to like word salads…ESPECIALLY love the message there of the import of aware, nonverbal communication and unconditional love.
Far as this water post goes, it’s wisely informative and only want to mention that one shouldn’t drink much of ANYTHING right before or during eating (not good to dilute stomach acids that aid in digestion).
Also, on a related note, what about our oxygen requirement? Biology says we get 15-20% through our SKIN…which is not usually thought of as a respiratory organ. It also says that even a drop of a few percent can have physiological and cognitive effects on our calorie and oxygen gobbling brains. Need to be careful of makeup, moisturizers, sunblock, dirt/grime, and most especially, dead skin cells which need to be regularly cleared from one’s pores. I use a LOOFA SPONGE (natural sea sponge commonly available)…just have to be careful of scraping elders’ tender skin too hard. Make sure you are getting as much oxygen as you can through both your lungs AND skin!
Best wishes,
Charlie Macknee
Wow, that’s awesome information, Charles! In addition to your comments about cosmetics, I’d add that skin has natural oils that should not be washed off constantly with cleansers. Why pay for cosmetics to strip you of the body’s natural protectant, then pay again to replace it with man-made approximations? If you want to retain your youthful skin (and apparently, your mind), throw away most of your cosmetics.