Sometimes, changes that look like “part of the dementia” are actually the body responding to something physical. Understanding what these changes might mean — and what to do about them — can make a real difference.
You might notice that the person you support:
- Seems suddenly more sleepy or less responsive
- Goes quiet or “zones out” without warning
- Looks pale or a bit washed out
- Becomes unsteady on their feet
- Slumps, dips, or even falls when standing up or after sitting for a while
These changes can be unsettling. In some cases, they may be linked to drops in blood pressure — something that is more common in dementia than many people realise, and more manageable once you know what to look for.
What is low blood pressure?
Blood pressure is the force of blood moving around the body. When it drops too low — a condition known as hypotension — the brain may not receive enough blood flow for a short time.
This can lead to symptoms such as:
- Dizziness or light-headedness
- Unsteadiness
- A glazed or distant appearance
- Sudden fatigue or drowsiness
- Fainting (also called syncope)
These drops can happen at any time, but they are particularly common when moving from sitting to standing. This is known as postural hypotension, or orthostatic hypotension.
Is there a link with dementia?
Yes — and it is more common than is often discussed.
Dementia affects the brain in ways that go beyond memory and thinking. Over time, it can disrupt the systems the brain uses to regulate the body — including heart rate and blood pressure. This happens across different types of dementia, not just specific ones. Whether someone has Alzheimer’s disease, vascular dementia, Lewy body dementia, frontotemporal dementia, or another form, the risk of blood pressure changes increases as the condition progresses. The link is particularly well-documented in Lewy body dementia, where research suggests more than half of those diagnosed experience orthostatic hypotension — but it is by no means limited to this condition.
This is not inevitable for everyone, but it is common enough that all carers — family and professional — should be aware of it.
Why blood pressure can drop in later stages
As dementia progresses, the body can become less able to maintain stable blood pressure. This is usually due to a combination of factors rather than a single cause.
- Changes in how the brain regulates the body: The autonomic nervous system — which controls automatic functions like heart rate and blood pressure — can be affected by dementia. As this happens, the body becomes less able to respond quickly to changes in position or activity, making sudden drops more likely.
- Reduced movement: Spending more time sitting or lying down can affect circulation and make it harder for the body to adjust when moving.
- Dehydration: Reduced thirst or difficulty with drinking means many people with dementia take in less fluid, which lowers blood volume and can cause blood pressure to drop.
- Reduced food intake: Eating less affects general physical health and can contribute to blood pressure instability.
- Medication effects: Some medications commonly used in dementia care — including certain antipsychotics, antidepressants, diuretics, and blood pressure tablets — can lower blood pressure, sometimes more than intended as the body becomes more sensitive over time. It is worth asking for a medication review if blood pressure changes are a concern.
- General physical decline: Reduced muscle mass, reduced activity, and changes in heart function all play a role over time.
These changes tend to become more noticeable as dementia progresses. At this stage, the person may not be able to tell you that they feel dizzy or unwell before a fall happens — which makes it even more important for the people around them to recognise the signs.
What it can look like
Blood pressure drops are not always obvious. They can be brief and may easily be mistaken for a sudden worsening of dementia symptoms.
You might notice:
- Sudden unsteadiness or wobbling
- Paleness or clammy skin
- A glazed or distant expression
- Slumping in a chair or while standing
- Falls, particularly when standing up or after sitting or resting for a long time
- Episodes where the person briefly becomes unresponsive or “checks out”
In some cases, a person may faint (syncope). Occasionally, fainting can be accompanied by brief jerking or twitching movements — sometimes called convulsive syncope. This can look similar to a seizure, but it is caused by a temporary drop in blood flow to the brain rather than a neurological seizure. These episodes can be frightening to witness, but understanding what may be happening helps guide the right response.
It is also worth noting that blood pressure can drop after meals, as blood is directed to the digestive system. If episodes seem to happen shortly after eating, this may be a factor worth mentioning to a GP.
Simple things that may help
There are practical steps that can reduce the risk of sudden drops in blood pressure:
- Encourage slow, supported changes in position — for example, sitting quietly for a moment before standing, rather than moving quickly
- Offer regular drinks throughout the day to help maintain hydration
- Ensure the person is supported and steady when standing, particularly after sitting or lying down for a period
- Keep a note of when episodes happen — the time of day, whether it was after a meal, after changing position, or after a period of inactivity. This information is genuinely useful for a GP or healthcare professional
- Share any concerns with the GP or healthcare team, particularly if changes are new, increasing in frequency, or leading to falls
When to seek support
Speak to a GP or healthcare professional if you notice:
- Frequent dizziness or unsteadiness
- Falls or near-misses
- Episodes of fainting or brief unresponsiveness
- Sudden or unexplained changes in alertness
- New or worsening symptoms that seem physical rather than purely cognitive
A GP may review medications, check hydration, monitor blood pressure at different times of day, or explore other possible causes. Sometimes a simple medication adjustment makes a significant difference.
A final thought
Not every change is “just dementia.” Sometimes the body is responding to something that can be understood, monitored, and supported.
The people who spend time with someone living with dementia are often the first to notice that something is different. Noticing these patterns — and feeling confident to raise them — is an important part of care. It helps ensure that physical needs are recognised alongside cognitive changes, and that the person receives the right support at the right time.
Want to understand more about how dementia affects the brain?
The physical changes described in this article are part of how dementia progressively affects the brain’s ability to regulate the whole body — not just memory and thinking. If you’d like to understand more about this, our article The Orchestra Analogy: Understanding How Dementia Affects the Brain explains this in an accessible way.
If you have questions about dementia care or are interested in training for yourself, your team, or your organisation, get in touch — we’d be happy to help.