November 30, 2015

Homocysteine And Dementia..Chicken Or Egg?

Which Comes First - High Homocysteine Or Dementia?

In his discussion of causality Bradford Hill noted that the issue of 'temporality' was of particular relevance for diseases of slow development, such as dementia.. i.e., any causative factor must, of course, precede the disease it is associated with!

The example he gave was relevant to dementia; i.e.- whether a particular diet resulted in disease, or whether the early stages of disease, such as dementia, led to peculiar dietetic habits.

Homocysteine, Dementia And Nutrition:

Early reports suggested that high blood homocysteine levels in patients with dementia was likely to be independent of nutrition. In several initial studies the stability of homocysteine levels over time, and lack of relationship with duration of symptoms, argued against the relationship being a consequence of the dementia.

In another early study, the investigators also measured retinol binding protein, a vitamin A transport protein sensitive to nutritional intake. They found no difference between patients and cognitively intact controls. This implies that malnutrition is not a likely cause of Alzheimer Disease related hyperhomocysteinemia.

Later Prospective Studies:

Many prospective studies have since confirmed that high blood homocysteine levels predict and pre-date dementia and cognitive decline by years.  In fact, the longest follow-up period to date is 35 years.

This is worth re-stating. Remarkably, your blood homocysteine level at mid-life PREDICTS your risk of dementia 35 years later - the higher the homocysteine, the higher your risk!

 

In our next Blog update, we will look at the 'gradation' of risk between homocysteine levels and dementia. We'll show how the higher your homocysteine level is in mid-life, the greater your risk of developing dementia.

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