Although no one knows what causes Alzheimer's disease, many research studies indicate that those who regularly eat fatty fish or who supplement with fish oil have a lower risk of developing Alzheimer's disease later in life.
Why this is the case remains an interesting topic of investigation but it is believed to be due, at least in part, to the role Omega 3 fatty acids play in the general functioning of the brain itself.
Omega 3 fatty acids are known to improve mental function, mood, memory and concentration and have already demonstrated considerable success in the treatment of conditions such as depression, anxiety, bipolar disorder, schizophrenia, ADD and ADHD. Currently there is no cure for Alzheimer's, although research does indicate that Omega 3 fatty acids can slow down the ageing of the brain and possibly delay the onset as well as slow down the progress of Alzheimer's too.
One research team from Aberdeen and Edinburgh University led by Professor Lawrence Whalley, questioned approximately 300 people aged 64 on their Omega 3 intake, they also tested their blood levels of Omega 3. The participants had previously taken part in a survey on IQ in 1947 when they were 11 years old. They found that those who had taken Omega 3 supplements showed better results on mental speed tests and there was even an association between the results and the level of Omega 3 in the blood of the participants. The team reported that the evidence seemed to suggest that Omega 3 could slow down the ageing of the brain and help it to work faster.
Another study conducted by Uppsala University in Sweden looked at the effect of Omega 3 fatty acids on patients who already had Alzheimer's disease. Researchers gave 89 patients the Omega 3 fatty acids Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA) for a period of 6 months and another 85 were given a placebo in the form of corn oil. After the initial 6-month period, the placebo group also switched to Omega 3 for a further 6 months. Although there was no real differences noted between the two groups in general, there was an interesting result where 32 patients who had milder mental impairment showed less of a decline whilst taking Omega 3.
The results of both these studies indicate that Omega 3 supplementation might not only improve mental function in the twilight years, it could possibly be beneficial in slowing down the progress of Alzheimer's disease, particularly in the early stages, however, more research is required to substantiate this.
DHA deficiency and the "fatty acid paradox"
The brain is composed mostly of fat, in particular, the Omega 3 fatty acid Docosahexaenoic acid (DHA). Patients with Alzheimer's disease and other forms of dementia have shown very low concentrations of DHA in the brain indicating a possible DHA deficiency. This has naturally led to the conclusion that supplementing with DHA might offer therapeutic help.
However, what has been dubbed the "fatty acid paradox" is the belief that the best way to correct any DHA deficiency is not by increasing intake of DHA as what one might expect, but to increase intake of EPA instead. If enough EPA is present, the body can produce DHA as required.
EPA is believed to inhibit the activity of the enzyme phospholipase A2. Over-activity of this enzyme is associated with neurotoxicity and death of brain cells and is a feature of Alzheimer's disease as well as other neurodegenerative diseases.
What is Alzheimer's disease?
Alois Alzheimer first identified Alzheimer's disease in the early 1900's. It affects over half a million people in the UK alone. It is characterised by progressive mental decline and begins with periods of memory loss, confusion, and personality changes before proceeding to full-blown dementia with complete loss of most cognitive abilities and even physical abilities.
No one knows what causes it, it is irreversible and there is no cure. It is relatively rare under 50 years of age but the chances of developing it increase the older you become. Medication is aimed at slowing down the progression of the disease. It is not the same as normal age-related cognitive decline where some impairment in mental function is considered a normal part of the ageing process.
Although no evidence exists that Omega 3 fatty acid supplementation prevents you from developing Alzheimer's disease, the indications are that increasing intake of Omega 3 does decrease your risk of developing Alzheimer's disease later in life. There are indeed many other health benefits afforded by getting an adequate amount of Omega 3 in the diet including increased protection against cardiovascular disease, arthritis and many other inflammatory conditions.
Bearing in mind the toxicity risk involved in eating too much fresh fish, supplementing with high quality fish oil would seem the best way to gain the protective benefits associated with Omega 3 fatty acids.