I learned this week that life expectancy in the UK has reached an all-time high. Yet, while quantity of life is important to most of us, so is quality of life. What the life expectancy statistics don’t tell us about is health issues that can come as part and parcel of the ageing process that can erode our capacity to lead full and active lives.

One health issue that our increasingly ageing population has brought to the fore is dementia. In a previous blog I wrote about how the National Institute for Health and Clinical Excellence (NICE) in the UK has decided, on the balance of evidence, not to sanction the use of drugs specifically designed for dementia sufferers. Now, it seems that the drug industry are set to take legal action against NICE in an attempt to get this decision reversed (something that I see as a very worrying turn of events indeed).

With all this news about longevity and Alzheimer’s disease circulating in my mind I was interested to read about a study published this week in the Archives of Neurology which has found an association between the fatty nutrient docosahexaenoic acid (DHA) and a reduced risk of dementia.

DHA (the long name for which is docosahexaenoic acid) is one of the two types of so-called omega-3 fats found in ‘oily’ fish such as salmon, mackerel and sardine. In the Archives of Neurology study, individuals with the highest levels of DHA in their bodies, compared to those with the lowest levels, had about half the risk of developing dementia. Risk of Alzheimer’s disease was down by about 40 per cent too. This protective association persisted even after other factors that can confuse the issue (such as age and gender) were taken into consideration.

Sorry if I’m repeating myself, but elsewhere I’ve been keen to stress that studies of this nature (known as ‘epidemiological’ studies) may show associations between things, but do not prove that one causes or protects against the other. However, there is a plausible mechanism by which DHA may protect against dementia in that it is thought to be important for the structural integrity of the brain. In an editorial that accompanies the Archives of Neurology study, Dr. Martha Clare Morris of Rush University Medical Center in Chicago. USA notes that there is a “strong biological basis for the association of DHA and neuroprotection”. No wonder fish is sometimes referred to as ‘brain food’.

The kind of DHA level associated with significant protection from dementia and Alzheimer’s was in the order of 180 mg per day. Including oily fish in the diet will obviously help us to meet our needs for DHA. Another option, for those who do not like fish, is fish oil supplementation. Depending on the size of capsule and concentration of DHA, 180 mg usually equates to only one capsule of fish oil a day. Keeping up a good intake of DHA may prove a useful strategy for ageing individuals keen to do what they can to keep from losing their minds.

References:

1. Schaefer EJ , et al. Plasma Phosphatidylcholine Docosahexaenoic Acid Content and Risk of Dementia and Alzheimer Disease: The Framingham Heart Study
Archives of Neuroogy. 2006;63:1545-1550.

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