Meta-Analysis: 9 Risk Factors for Alzheimer’s Disease

Written by Nicole Scheidl

September 2, 2015

A recent meta-analysis identified nine factors which increase the risk of Alzheimer’s Disease. The analysis was published in Journal of Neurology, Neurosurgery and Psychiatry by Dr. Yu of the Memory and Aging Center at the University of San Francisco.

The risk factors identified in the analysis are:

  1. obesity,
  2. carotid artery narrowing,
  3. low educational achievement,
  4. hyperhomocysteine,
  5. depression,
  6. hypertension,
  7. frailty,
  8. current smoking, and
  9. type 2 diabetes (diabetes only in Asian populations).

Let’s look at these factors in a little more detail.


High or low BMI (body mass index) was associated with an increased risk for developing Alzheimer’s disease in later life. So in your 40s or 50s it is important to maintain a healthy weight, but that risk factor seems to disappear as you age. For example, a high BMI in later life is not a significant risk factor.

There may be many reasons why a high or low BMI affects risk factors. The brain needs a certain amount of fat to function well so an undernourished body deprives your brain of needed building blocks. Check out our blog post on the Fat Brain here.

Cartoid Artery Narrowing

The cartoid arteries run up either side of your neck into the front part of your brain. The brain requires good blood flow to get all the oxygen and nutrients it needs to function well.

If your cartoid arteries are not providing optimal blood flow your brain will suffer. Cartoid artery narrowing can be caused by the build-up of fatty substances or cholesterol. This is where a good diet can make a big difference in brain health.

Low Educational Achievement

In a recent blog post we talked about your fourth grade marks as a risk factor for Alzheimer’s disease. What is really behind that tongue-in-cheek risk factor is the fact that brain engagement matters. The more novel and complex activities you engage in, the better your brain fitness. A stronger brain means a lower risk factor for developing dementia.

If you did not develop a habit of curiosity and wonder in your early years of school, it is likely you checked out later on. Remaining curious and continuing to learn reduces risk factors and also makes life worth living!


Hyperhomocysteine is not only a killer to say – but also has a negative impact on our bodies.

Homocysteine is a product of protein metabolism.

It is a toxic amino acid that is produced naturally in almost every cell in our bodies. It can be metabolized and converted into useful tasks but vitamins B6, B12 and Folic acid are essential. Without sufficient levels of these nutrients, hyperhomocysteine results.

How do I get sufficient nutrients to lower homocysteine levels?

Eating a whole food diet, especially rich in leafy greens, whole grains, legumes and fruits will lower your homocysteine levels,  reducing health risks and increasing brain health.

Choosing alternate proteins such as oily fish (sardines, mackerel, herring, anchovy and salmon), tofu and beans also helps. It keeps your menu interesting!


Depression can be a self-fulfilling prophecy, moving the brain towards the development of dementia.despairing man in chair

Individuals who are depressed often withdraw and isolate themselves. This limits their interactions with other human beings. Science shows that limited social interaction speeds cognitive decline.

Benjamin Franklin wrote,

“A man wrapped up in himself makes a very small bundle.”

If we are only focused on ourselves we make a small bundle of the greatness we could be. So maintain social networks and find activities that are meaningful to you. It will make a difference.


Good blood flow to the brain is an essential part of brain health and so it is no surprise that hypertension becomes a risk factor for Alzheimer’s disease. The stronger the brain is, the longer it can buffer against a disease like Alzheimer’s.

It makes sense then that a brain weakened by hypertension is going to be more at risk for dementia. Pay attention to your blood pressure – have it checked at least every two years.

High blood pressure can cause havoc on your blood vessels without any other obvious symptoms. So don’t ignore the simple but effective step of having your family doctor check your blood pressure.


Frailty is an interesting risk factor. When an individual loses mobility and muscle mass, their overall weakness makes them vulnerable to falls and hip fractures.senior woman

A fall or hip fracture can have a very negative effect on an individual’s health. The experience of hospitalization, the effect of anesthetics and the inability to get out to take part in a regular social life, means that the individual’s regular ‘cognitive stimulating activities’ decline or disappear.

My favourite way to fight frailty is to lift weights! I really like the effect of light, repetitive weight-lifting. It is easy to avoid injuries from lifting weights that are too heavy and it also builds up endurance as well as strength.

If you can’t get out to the gym, you can even use a soup can…after 50 repetitions you will feel your muscle!

Current Smoking

If you are still a smoker after all these years, maybe the knowledge that it can raise your risk of developing dementia will be motivation to seek help to quit.

Smoking will reduce the oxygen levels in your brain…and a brain starved for oxygen is not going to be a happy brain.

Enough said.

Type 2 Diabetes in the Asian Population

This is one of the unusual  findings of the meta-study.

Type 2 Diabetes and the role of insulin treatment on the brain have been the subject of recent study. The research suggests that individuals who are diabetic but are taking insulin treatment may be reducing their risk of dementia.

It may be that the non-Asian population has been more extensively involved in insulin treatment and that is why you are seeing the anomaly in the meta-study.

Whatever the case, this is creating a new and exciting area for treatment options.

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