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Dehydration and Dementia

While the overall risk of dehydration can increase as you get older, the risk is particularly acute if you have dementia. Here’s how to spot it and prevent it…

What is dehydration?

Someone with dementia will become dehydrated when they lose more water from their body than they take in.

Water is needed in the body for a wide range of uses including regulating temperature (through sweating), maintaining blood pressure and eliminating bodily waste, as well as a host of cell reactions. In men, the body is made up of around 60-65% water. In women, it’s 60% water.

Even mild dehydration can start to have an effect on people, causing tiredness, headaches and a lack of concentration. But in more severe cases, it can cause confusion, delirium and in the very worst case scenarios, death.

Mild dehydration is defined as losing 2% of your body weight. Severe dehydration occurs with 4% or greater body weight loss.

Causes of dehydration in people with dementia

Dehydration can be a common challenge for people with dementia, particularly if they are also elderly. This is due to:

Forgetting to drink

It seems simple enough – you feel thirsty, so you take a drink. But for someone with dementia, changes in the brain can lead to two issues. They either forget to take a drink regularly, perhaps making a cup of tea and then forgetting where they’ve left it. However, sometimes the part of the brain that recognizes that you’re dehydrated and sends a message to let you know you’re thirsty, isn’t working properly. So they may be feeling parched, but not actually realize that the feeling they have is thirst, and that taking a drink would help with it.


Some drugs can have a diuretic effect on people. This means that it causes the person to urinate frequently, meaning they lose fluids more quickly. Blood pressure drugs often have a diuretic effect.


If the person you care for has developed a bug, it can have an effect on their hydration levels. Diarrhea and vomiting can lead to a loss of fluids, so it’s vital that these are replenished at regular intervals if your loved one gets ill.

Inability to swallow

In the later stages of dementia, it can become harder to swallow, as the brain struggles to send messages to the mouth and throat to tell it what it needs to do when drinking. This can lead to choking or dribbling and a loss of fluid.

Lack of mobility

If your loved one has limited mobility – either because of dementia or due to another health condition such as arthritis or rheumatism – they may struggle to get up from a chair or bed regularly to get a drink.

Symptoms of dehydration

- Increase in confusion, delirium (over and above typical dementia symptoms)

- Urine is dark and strong smelling

- Skin may appear drier and more papery than usual

- Lips are cracked and dry

- Urinary tract infections (which can also cause delirium)

- They may complain of a headache

- Eyes become sunken

- Blood pressure is lower

- Pulse is fast, weak and/or irregular

The trickiest symptom to work out is the increased confusion and delirium you can experience when dehydrated. Many people with dementia will already have days where they seem very confused, and other days where they’re more lucid, so knowing when these symptoms might be caused by dementia, versus dehydration can be difficult.

It’s why you need to factor in other symptoms of dehydration, such as changes in urine colour or skin dryness, to confirm that they are in need of extra fluids.

Did you know?

One in five older people living in care homes is dehydrated, according to a joint study carried out by researchers from the University of East Anglia (UEA) and Canberra University in Australia.

Preventing dehydration

If you’re concerned about a loved one with dementia becoming dehydrated, there are steps you can take to help prevent it.

Leave out jugs of water

Make it as easy as possible for your loved one to have regular drinks of water or other fluids throughout the day by placing cups and jugs of water in areas around the house. For example, next to their favourite chair in the living room and by their bedside.

Make drinking easier

If they have limited dexterity or co-ordination, and struggle to drink from a cup, a water bottle with an easy-to-open top could be useful. You can also serve drinks in two-handled cups with sturdy bases, which will help to prevent spillage and maintain dignity. One-way straws (which let you suck fluid up without it then falling back down the straw if suction is weak) can help to maintain hydration levels.

Set up reminders or leave notes

If your loved one needs a gentle nudge to remind them to have a drink regularly, you can put up notices around the house, and even set up electronic reminders. These can be programmed into day clocks or specific electric memos which will play at certain times, or if they detect the movement of someone walking past them.

Get creative

Remember, you don’t have to only provide plain tap water, and even if you do, you can make it a bit more interesting by adding slices of lemon, orange or cucumber, or adding a splash of squash or cordial. Herbal teas are a great option for boosting hydration, but even regular tea and coffee will help. Many people worry that because the caffeine in them has diuretic properties, they’re not appropriate for boosting hydration. However, the amount of caffeine in a cup of coffee is relatively small, so it will still hydrate you to a certain extent.

Provide high water content food

If the person you care for doesn’t particularly like drinking drinks, you could also try offering foods that are high in fluids. Go for things like broth, apples, oranges, berries, grapes, watermelon, cucumber and cottage cheese.

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