Having high blood pressure or hypertension is a recognised risk factor for Alzheimer’s and other forms of dementia, particularly vascular dementia.
The simple act of getting your blood pressure checked by your doctor regularly is paramount.

You can’t tell when your blood pressure is up. But your doctor can. Keeping your blood pressure within the normal range is very important for both heart and brain health.

There are some simple lifestyle choices, which can help keep your blood pressure normal:

• Keep your weight in the healthy range
• Exercise daily – gotta “find that thirty”
• Eat healthily with lots of green leafy vegetables and fruit
• Manage stress levels through exercise, meditation or mindfulness
• Stop smoking
• Cut the salt

If you are doing all of the above and your blood pressure is still too high, then it may be time to consider using an antihypertensive. This is where the choice of which antihypertensive used can possibly make a difference for preventing Alzheimer’s or slowing down the progression of the disease if already present.

At least that what research from a large observational study in the UK has found.
The findings from this study have been published in the Journal of Alzheimer’s Disease and indicate that for older patients (age 60+) being prescribed what is called an angiotensin 11 receptor blocker (ARB) was associated with a 53% lower risk of developing Alzheimer’s disease compared to a 24% reduction for those prescribed an angiotensin converting enzyme (ACE) agent.

These findings come from an observational study of over 9000 patients aged 60+ who were diagnosed at some time between 1997 and 2008 with either probable or possible Alzheimer’s disease or other dementia. The data suggested that being prescribed an ARB or ACE was associated with a lowered risk of developing Alzheimer’s disease, vascular or other dementia. Controlling for control and age, and other illnesses made no difference to the risk reduction and there was also noted to be an apparent dose- response relationship between ARBs and Alzheimer’s.

This research supports the move to now undertake actual clinical trials to verify these findings.

These results support findings from previous studies conducted elswhere. In 2010 a study from Boston University School of Medicine compared the incidence of Alzheimer’s disease and dementia in men taking ARBs compared to either the ACE drugs or other antihypertensives.

Reducing Alzheimer’s incidence and nursing home admission.

In this study a significant reduction in the actual incidence of Alzheimer’s and other dementia was reported as well as a reduction in the rate of disease progression measured in terms of lengthening time to admission to a nursing home or death.

Dr Wolozin reported that those people who did the best were prescribed a combination of an ARB and ACE with 55% reduction in the incidence of Alzheimer’s and other dementias and a 70% reduction in nursing home admissions. Being prescribed an ARD on its own was associated with a 50% reduction of risk of incidence of Alzheimer’s.

This in itself is of major implications as keeping a person with Alzheimer’s or other dementia at home for longer is highly desirable as well as a major cost saving.
In this study, data was collected from the US Veterans Affairs administrative database (this contains information on over 5 million people!) looking at the rate of incidence of Alzheimer’s or dementia being diagnose over a four years period in men over the age of 65 with a history of cardiovascular disease. The subjects were divided into three groups taking either a) an ARB b) taking an ACE (Lisinopril) or c) taking other cardiovascular drugs.
Adjustments were made for age, diabetes, stroke, cardiovascular disease and the findings were that those taking the ARB drugs had a lower incidence of Alzheimer’s and significantly lower risk of being admitted to a nursing home, again with a dose response for the ARB.

So why the difference?

Both ARBs and ACEs work by reducing angiotensin 11 signalling at the level of two receptors AT1 and AT2.
ARBs appear to make the difference by selectively inhibiting the angiotensin 1 receptor.

If the AT1 receptor is stimulated, this leads to vasoconstriction.
If the AT2 receptor is stimulated, this leads to vasodilation, neuronal differentiation and neuronal repair.
ARBs selectively inhibit the AT1 receptor, so vasoconstriction doesn’t occur and it is thought that this allows for increased blood flow to the brain and accounts for the neuroprotective effect.

Using a combination of an ARB and ACE was found to be of particular benefit perhaps because of the reduced risk of stroke and the ARB preventing vascular damage induced by beta amyloid that accumulates in the brain in Alzheimer’s disease.

The bottom line.

The most important factor here is to ensure that you keep your blood pressure in the normal range.

If you haven’t had your blood pressure checked in a while, NOW is a good time to make an appointment to see your doctor.

If you do have high blood pressure then ensure you make all the necessary lifestyle adjustments to see if you can bring it down to normal on your own.

If despite all this, your blood pressure remains elevated, talk to your doctor about which medication would be the most appropriate for you. Remember these observational studies are only suggestive that certain medications i.e. the ARBs may be of benefit in preventing the risk of Alzheimer’s and other dementias. Your doctor is in the best position to know which medication may be most suitable for your own particular needs. The main thing is to keep your blood pressure in the normal range.

Meanwhile further research will help to ascertain whether in fact the ARBs do have an advantage in helping to reduce the incidence of Alzheimer’s. Time will tell.

Do you know if your blood pressure is normal?

Refs:

Davies,N.M., Kehoe, P.G., Ben-Shlomo, Y., Martin, R.M.
Associations of Anti-Hypertensive Treatments with Azlheimer’s Disease, Vascular Dementia and other Dementias . Journal Of Alzheimer’s Disease October 2011 pg 699-708

Boston University Medical Center (2010, January 12). Angiotensin receptor blockers associated with lower risk of Alzheimer’s disease. ScienceDaily. Retrieved October 31, 2011, from http://www.sciencedaily.com¬ /releases/2010/01/100112201345.htm

Sometimes a science report headline will grab my attention because it sounds so quirky and this one certainly hit the spot.
“Tiny Blood Vessels In Brain Spit to Survive”

I was intrigued, so I read on.

It turns out that capillaries, our really small blood vessels have a unique way of clearing out debris such as blood clot, cholesterol and calcium plaque out of harms way.

In the larger veins and arteries there is sufficient blood pressure to both push against a clot and break it into smaller pieces, or the body’s enzymes in the blood help to break it down.
In the capillaries the role of blood pressure is much less effective and for debris (other than clot) such as cholesterol, because it is difficult to dissolve. Prolonged obstruction in a capillary will reduce the supply of oxygen and nutrient to a particular area of brain tissue, which if not cleared quickly enough can then cause cell death.

The really neat thing that has been observed in mice studies was that the brain capillaries have devised a unique way to clear out obstructions. What happens is that the clot or debris becomes enveloped in a membrane produced by the capillary vessel wall. The outer original vessel wall then opens up and literally ejects or spits the debris out into the brain tissue. The envelope, which had covered the clot, then becomes the new vessel wall and the blood flow is restored. Clever!

The study also showed that the capillaries ability to perform this diminishes with age, which may be relevant when we are looking at what causes brain age related cognitive decline. The process may be up to 30 to 50% slower in older brains. If the obstruction is not removed this can lead to damage or death of the affected brain tissue and capillary. Small brain infarcts are associated with the onset of vascular dementia, the second most common form of dementia after Alzheimer’s disease.

So there we have it. A fascinating tale of how our spitting brain capillaries clear out the rubbish.

Ref: Carson K. Lam, Taehwan Yoo, Bennett Hiner, Zhiqiang Liu, Jaime Grutzendler. Embolus extravasation is an alternative mechanism for cerebral microvascular recanalization. Nature, 2010; 465 (7297): 478 DOI: 10.1038/nature09001

I was sitting in my GP’s office recently, being told something I didn’t want to hear. My blood pressure was too high and I needed to start medication with antihypertensives.

I didn’t want to have to take medication. I had always planned not to be on anything apart from fish oil and glucosamine supplements until I was at least 90 years old. I consider myself fit. I exercise daily, my weight is normal, I eat healthily, I don’t smoke and I keep an eye on how much wine I drink each week.

But my family history includes hypertension and stroke on both my mother’s and father’s side.
And I do recall a conversation with my obstetrician who was managing my pregnancy-induced hypertension a number of years ago. He said, “Jenny, you are likely to develop hypertension as you get older.” Harrumph. I heard, but didn’t want to listen. But who am I trying to kid?

I have what is called “essential hypertension”. The cause is as yet unknown.
I don’t like it. But I can deal with it and take my pills.
The reason why? Because I value my brain cells too highly not to. As a Doctor my medical training has taught me what the consequences of untreated hypertension are.

Hypertension has been described as a silent killer. You can’t feel if your blood pressure is too high. We rely on readings taken with a sphygmanometer to get an accurate idea of the state of our blood vessels.
The blood pressure reading essentially tells us the peak or systolic pressure our heart has to exert with each contraction to pump the blood around our body. The lower reading or diastolic pressure gives us the resting pressure of the circulatory system in between heartbeats.

If the readings are too high we run the increased risk over a period of time of blood vessel rupture causing a stroke or cerebrovascular accident. Other organs are affected as well, including the kidney, eye and heart. None of which is good news.

So, back to the brain and high blood pressure. Sure it’s good not to be at risk of stroke. But what about the effect of high blood pressure on memory and cognition?

Studies have shown that having high blood pressure can contribute to memory loss and other decline in brain function in people over the age of 45.

In one study of over 19000 participants aged 45 or older, they found that with each 10-point increase in diastolic pressure, the risk of cognitive difficulty increases by 7 points.

But how high is high?
We need to keep our diastolic pressure (the lower of the two reading indicating the pressure of the arterial system at rest) at below 90mmHg.

With around 25-30% of the Australia adult population having high blood pressure I am clearly not alone.
For the vast majority of people like myself we have “essential hypertension” where no specific cause is identified. However having high blood pressure causes problems by causing our arterial walls to thicken and lose their elasticity, leading to reduced blood flow and tissue death.

Having reduced blood flow to your brain becomes an issue when you need it to be working harder. For example when you want to be able to pay attention or work out a solution to a problem, the decrease of available blood flow to your brain leads to fewer brain cells being activated and an increased number of memory lapses happening as a result.

In older people, having high blood pressure can predict who is at risk of developing impaired executive function (organising, planning and decision making) and a greater risk of progressing to dementia. One study of 900 octogenarians showed that high blood pressure was associated with an increased risk of developing dementia when frontal lobe functioning was impaired

Because stroke and TIA are leading causes of risk of cerebrovascular disability followed by dementia, controlling hypertension is a simple and effective way to significantly potentially reduce the incidence of forecasted dementia in this group.

So attending to diagnosing and treating hypertension in midlife would appear to be essential to protect you from developing cognitive impairment further down the track.

If you are over 45 and haven’t had your blood pressure checked for a while, now would be a good time to make an appointment and get it checked by your GP.

If it is too high then some simple lifestyle changes could help:

• Keeping your weight in the healthy range
• Don’t smoke
• Reduce your alcohol consumption.
• Do some regular exercise
• Keeping your cholesterol in the normal range
• Eat less saturated fat.
• Use less salt in your diet.

Hypertension has no symptoms, but is easily managed and keeping it in the normal range could make a big difference to being able to save your brain.

References:
Shahram Oveisgharan; Vladimir Hachinski. Hypertension, Executive Dysfunction, and Progression to Dementia: The Canadian Study of Health and Aging. Arch Neurol, 2010; 67 (2): 187-192

JAMA and Archives Journals (2007, December 12). High Blood Pressure Associated With Risk For Mild Cognitive Impairment.

Radiological Society of North America (2007, November 29). High Blood Pressure May Heighten Effects Of Alzheimer’s Disease.