Dementia And Hydration

What is dementia?

Dementia is a term used by health professionals to describe common symptoms like memory loss and confusion, but also problems with speech and understanding, that worsens over time. Dementia is not a specific disease; however, several diseases can cause dementia. Having memory loss alone does not mean you have dementia, but it can be an early sign.

The most well-known type of dementia is Alzheimer’s disease; however, there are more than 200 subtypes of dementia, like vascular dementia or Lewy body dementia. Each type of dementia stops a person’s brain cells (or neurons) in specific areas from working properly. This decline in brain function causes their ability to remember, think, and speak to be affected.

By 2025, it is estimated that over one million people in the UK will have a diagnosis of dementia.¹ Dementia is typically seen in people over the age of 65, but it can affect people of all ages. It is important to note that dementia is not a natural part of ageing.²

Symptoms of dementia

The problems most described include issues with memory loss, speed of thinking, mental acuity, understanding, judgement, mood (managing behaviour or emotions), movement, doing daily activities, but also with language, like using words incorrectly or having trouble speaking. Aspects of your personality may change as well, and you may lose empathy or lose interest in relationships and socialising. Additionally, you may start to have hallucinations.²

As dementia progresses, it will become increasingly more difficult to maintain your independence as you will struggle to remember events and even things like when you have had your last meal or drink.

Can dehydration cause dementia?

Studies have shown that you only need to be 1% dehydrated to experience a 5% decrease in cognitive function. A 2% decrease in brain hydration can have short-term memory loss as a result. Staying dehydrated for prolonged periods of time will cause the brain cells to shrink in size and mass.³
In young people, specifically those assigned female at birth, these cognitive deficits were not permanent and were seen to be reversible by replenishing fluids.⁴ However, in the elderly, it was seen that the prolonged cellular stresses of dehydration could promote brain pathology and continue the decline in brain function. When older than 65 years, dehydrated individuals were placed at a higher risk for dementia.⁵

Severe dehydration and dementia show similar symptoms

Severe dehydration will show similar symptoms to dementia. They include memory issues, mental confusion, cognitive decline, changes in behaviour, weakness, fatigue, agitation, and dizziness. Also important to note is that being dehydrated can increase the risk of a urinary infection, which can also cause an acute phase of confusion in the elderly.^3-6

Dehydration is common in people with dementia

Parts of the brain that act on the feeling of thirst/recognize thirst are commonly affected by dementia. With age, the brain also becomes less sensitive to sensing thirst, making it a less reliable indicator of hydration status.⁷ Additionally, the person with dementia may not remember being thirsty or how to get themselves a glass or some water. Maybe their verbal communication has declined so far that they cannot express their thirst, or they do not understand why they need to drink. They could be on medication increasing their output in urine or perspiration, so they will need to drink more than usual. They could suffer from a fear of incontinence, so they will restrict their fluid intake, causing them to be dehydrated.^5,8

Conclusion

It is important to stay well hydrated. Studies have shown that 1% dehydration can cause a 5% decrease in cognitive function. To keep a healthy adult hydrated, they need to be drinking about 6-8 glasses of water daily. When a person has dementia, it can become a challenge to make sure they drink enough water in a day. It is important for them to have reminders to drink, in the form of a helpful water bottle with a straw they can carry with them or little alarms or notices that will nudge them to drink water. It is also an idea to give them foods with higher water content, like cucumber or watermelon, and provide easy access. People who become dehydrated show a decline in brain function, which can be reversed if spotted early; however, if left for a long time, it can become permanent as the brain cells shrink in size and mass.