This morning, I saw a fellow doctor share an interesting comment in a doctors’ chat group:

“Now there’s going to be more hypertensive patients who refuse to take medication.”

In plain English: more patients with high blood pressure may start refusing blood-pressure medication.

My first reaction was: that is actually possible.

Many people may read a headline and reason like this:

“Low blood pressure is linked to a higher risk of Alzheimer’s disease. So does that mean having slightly higher blood pressure is better?”

If you only read the headline and not the study, it is easy to reach that conclusion. But that conclusion is wrong.

What did the study actually find?

The study combined data from nearly 800,000 people, including the UK Biobank and the All of Us Research Program.

The researchers found that several cardiovascular conditions were associated with an increased risk of Alzheimer’s disease, including:

  • Low blood pressure
  • High blood pressure
  • Heart failure
  • Atrial fibrillation
  • Ischaemic heart disease
  • Stroke

The most important word here is association, not causation.

The study did not prove that low blood pressure causes dementia. It found that people with low blood pressure were more likely to be diagnosed with Alzheimer’s disease in the future. Those are two very different statements.

Why might low blood pressure show a strong association?

1. Reverse causation

This is a common issue in studies involving older adults. Some elderly patients may not develop dementia because their blood pressure is low. The sequence may instead look like this:

  1. Early neurodegenerative disease begins.
  2. Autonomic nervous system function declines.
  3. Blood pressure gradually becomes lower.
  4. Alzheimer’s disease is diagnosed years later.

When we look back at the database, it may appear that people with low blood pressure are more likely to develop dementia. In reality, the order may be reversed.

Low blood pressure may be an early sign of disease, rather than the cause of disease.

2. Poor blood flow to the brain

This is also something we see in clinic. Some elderly patients have heart failure, severe atrial fibrillation or coronary artery disease. Their blood pressure may not be high; it may even be low.

The real issue is not just the number. The heart may not be pumping well. Over time, poor blood flow to the brain may contribute to cognitive decline.

3. Overall frailty

Many older adults with muscle loss, poor nutrition, multiple chronic illnesses or general frailty naturally have lower blood pressure. These patients are also already at higher risk of dementia.

Seeing low blood pressure and dementia appear together is therefore not surprising. It still does not mean that low blood pressure directly causes dementia.

Do blood-pressure medicines increase dementia risk?

Current mainstream evidence points more in the opposite direction.

One of the best-known studies is the SPRINT MIND trial. It found that intensive blood-pressure control was associated with reduced mild cognitive impairment and a trend towards lower dementia risk.

Not every result reached the strictest level of statistical significance, but the overall direction was consistent: controlling high blood pressure is more likely to protect the brain than harm it.

A common misunderstanding in clinic

In my clinic in Singapore, I often hear patients say:

“Doctor, my blood pressure is now 130/80. It is normal already. Why do I still need to continue medication?”

The goal of blood-pressure medication is not only to make today’s reading look good. It is to reduce the future risk of:

  • Stroke
  • Heart attack
  • Heart failure
  • Kidney failure
  • Vascular dementia

Some patients feel that they have “more energy” when their blood pressure is slightly higher. This can happen, especially in people who have lived with high blood pressure for many years. When their blood pressure comes down, the body may need time to adjust.

That does not mean high blood pressure is healthier. It may simply mean that the body has become used to an unhealthy baseline.

Two very different kinds of “low” blood pressure

Pathological low blood pressure

Low blood pressure caused by heart failure, malnutrition, neurodegenerative disease, chronic wasting illness or severe frailty may reflect underlying illness.

Normal blood pressure achieved with treatment

Readings such as 120/70, 125/75 or 128/78 are generally healthy readings. They are not the same as pathological low blood pressure, and we should not compare them as if they were.

A GP’s concern

My concern is not really the study itself. My concern is how the study may be misunderstood.

One patient may ask, “Doctor, is 120/70 too low?” Usually, the answer is no, not usually.

Another may say, “I read that low blood pressure increases dementia risk. I don’t want to take my blood-pressure medication anymore.” This is the harder conversation.

The problem is not that the patient is wrong, or that the study is wrong. The problem is that many people see the headline but do not see the study design.

Final thoughts

I completely understand why patients feel confused. There are more medical studies, news headlines are getting shorter, and social media spreads information faster than ever. But the human body cannot be explained by one headline.

The real message from this study is not that higher blood pressure is safer. It is that heart health, blood-vessel health and brain health are deeply connected.

For most adults:

  • Around 120/80 is ideal.
  • Below 130/80 is generally good.
  • Persistently above 140 without control increases long-term risk.

So when you see a headline saying that low blood pressure is strongly linked to Alzheimer’s disease, please do not rush to stop your blood-pressure medication.

Very often, protecting your blood vessels also means protecting your future brain.

Important: Blood-pressure targets and medicines should be personalised. Speak with your own doctor before changing or stopping treatment.