Alzheimer’s disease (AD) is a chronic neuro-degenerative condition that places a traumatic burden of 
care on the NHS and the family and friends of the affected individual. The major hallmark of the disease is the formation of plaques from accumulated fragments of b-amyloid (Abeta), derived from amyloid precursor protein, which results in brain damage. A number of new studies have examined the effect of omega-3 fatty acids on the risk of developing AD, generating a number of hypothesis as to the mechanism behind the protective effect of fish consumption.
DHA may help reduce Alzheimer’s risk via modulation of the lipoprotein LR11 LR11, a member of the lipoprotein family, is a neuronal sorting protein known to reduce the cleaving of amyloid precursor protein to b-amyloid by enzymes known as secretases, genetic polymorphisms that reduce levels of LR11 are associated with increased AD risk. Receptors for lipoproteins like LR11 are regulated by lipids. These facts have generated a hypothesis that DHA may help reduce Alzheimer’s risk via modulation of LR11 levels.
In this study it was reported that even low doses of DHA increased the levels of LR11 in rat neurons. Moreover, it was found that dietary DHA increased LR11 levels in the brains of rats or older mice genetically engineered to develop Alzheimer’s disease, when the researchers used a human neuronal cell line.
Click here to view the study abstract.
Weekly consumption of fish is associated with a decreased risk of developing Alzheimer’s disease
A total of 8,085 healthy people, living in 3 different French cities, were studied over 4 years; an independent committee of neurologists validated 281 incident cases of dementia (including 183 AD cases). Weekly consumption of fish was associated with a reduced risk of all-cause dementia and AD among those not carrying the apolipoprotein E4 gene. Routine use of omega-3 rich oils was associated with a decreased risk of borderline significance for all cause dementia. Interestingly regular consumption of omega-6 rich oils not balanced out by consumption of omega-3 rich oils or fish was associated with an increased risk of dementia.
Click here to view the study abstract
DHA improved blood circulation to the brain and reduced deposition of beta-amyloid fragments in old mice
This study examined the effects of dietary lipids on b-amyloid deposition and blood circulation in the brains of mice. Starting at 6 months of age, mice were fed a regular rodent chow, a Typical Western Diet (TWD) containing 1% cholesterol or a diet with a high (0.5%) level of DHA, for 12 months. The DHA-enriched diet increased the volume of blood in the brain without changing blood flow, indicating improved circulation in the brain, and decreased the amount of vascular beta-amyloid deposition. TWD diet increased plaque burden in the hippocampus (the part of the brain required for memory formation).
Click here to view the study abstract.
DHA supplementation reduced accumulation of beta-amyloid fragments in the neuronal cells of mice
In this study reduced the intraneuronal accumulation of both amyloid-b (Abeta) and tau protein; combining DHA with n-6 fatty acids, either arachidonic acid or docosapentaenoic acid (DPAn-6), diminished the efficacy of DHA over a 12 month period. The authors observed that the reduction in soluble Abeta was attributable to a decrease in steady-state levels of presenilin 1 (mutations of this gene are associated with severe familial AD).
Click here to view the study abstract.
Omega-3 fatty acids may reduce cognitive decline in those with mild cognitive dysfunction
174 patients with AD, all stable and receiving an acetylcholine esterase inhibitor, were randomised to receive either a daily intake of omega-3 fatty acids (1.7 g of DHA and 0.6 g of EPA) or placebo for 6 months. Cognitive function was measured with the Mini Mental State Examination (MMSE) and the cognitive portion of the Alzheimer Disease Assessment Scale; at the end of the 6 months no significant differences in cognitive performance were seen between the two groups, however in a subgroup of patients with only mild cognitive dysfunction (scoring above 27 on the MMSE) a significantly slower rate of MMSE measured decline was observed in the omega-3 fatty acid-treated group compared with the placebo group; a similar reduction in rate of decline was observed between 6 and 12 months in patients with an equivalent profile in the placebo group when they were administered the omega-3 fatty acid supplement. These results suggests that omega-3 works optimally when administered in the early stages of cognitive decline.
Click here to view the study abstract.
DHA seen to have a protective effect on avoidance learning decline in rats infused with b-amyloid
This study investigated the relationship between the DHA-induced protection of learning deficit in a rat model of AD and changes in the fluidity of the fatty cell membrane surrounding neurons of the grey matter part of the brain (cerebral cortex). Oral administration of DHA increased the DHA content of the relevant cell membranes, lipid peroxidation (the process whereby free radicals, also known as reactive oxygen species, "steal" electrons from the fats in cell membranes, resulting in cell damage) decreased and cell membrane fluidity significantly increased; membrane fluidity was positively correlated with total avoidance learning. It is known that the less flexible the membrane, the less speedily messages will be transmitted between neurons and that the degree of fluidity directly reflects the fatty acid composition of the diet.
Click here to view the study abstract.
DHA rich diet decreased b-amyloid production in mice
Seven experimental diets with varying n-6/n-3-ratio, saturated and polyunsaturated fatty acid and cholesterol contents were fed to mice for 3-4 months beginning at 6 months of age; a typical Western diet with 40% saturated fatty acids and 1% of cholesterol increased, while diets supplemented with DHA decreased, Abeta levels compared to a regular (soy oil based) diet. Additionally DHA supplementation decreased the number of activated microglia (these are the central nervous system’s own immune cells) and increased exploratory behaviour in the mice. The favourable effect of DHA on Abeta production was verified in two different cell lines.
Click here to view the abstract.
Alzheimer’s disease (AD) is a chronic neuro-degenerative condition that places a traumatic burden of care on the NHS and the family and friends of the affected individual. The major hallmark of the disease is the formation of plaques from accumulated fragments of b-amyloid (Abeta), derived from amyloid precursor protein, which results in brain damage. A number of new studies have examined the effect of omega-3 fatty acids on the risk of developing AD, generating a number of hypothesis as to the mechanism behind the protective effect of fish consumption.
DHA may help reduce Alzheimer’s risk via modulation of the lipoprotein LR11 LR11, a member of the lipoprotein family, is a neuronal sorting protein known to reduce the cleaving of amyloid precursor protein to b-amyloid by enzymes known as secretases, genetic polymorphisms that reduce levels of LR11 are associated with increased AD risk. Receptors for lipoproteins like LR11 are regulated by lipids. These facts have generated a hypothesis that DHA may help reduce Alzheimer’s risk via modulation of LR11 levels.
In this study it was reported that even low doses of DHA increased the levels of LR11 in rat neurons. Moreover, it was found that dietary DHA increased LR11 levels in the brains of rats or older mice genetically engineered to develop Alzheimer’s disease, when the researchers used a human neuronal cell line.
Click here to view the study abstract.
Weekly consumption of fish is associated with a decreased risk of developing Alzheimer’s disease
A total of 8,085 healthy people, living in 3 different French cities, were studied over 4 years; an independent committee of neurologists validated 281 incident cases of dementia (including 183 AD cases). Weekly consumption of fish was associated with a reduced risk of all-cause dementia and AD among those not carrying the apolipoprotein E4 gene. Routine use of omega-3 rich oils was associated with a decreased risk of borderline significance for all cause dementia. Interestingly regular consumption of omega-6 rich oils not balanced out by consumption of omega-3 rich oils or fish was associated with an increased risk of dementia.
Click here to view the study abstract
DHA improved blood circulation to the brain and reduced deposition of beta-amyloid fragments in old mice
This study examined the effects of dietary lipids on b-amyloid deposition and blood circulation in the brains of mice. Starting at 6 months of age, mice were fed a regular rodent chow, a Typical Western Diet (TWD) containing 1% cholesterol or a diet with a high (0.5%) level of DHA, for 12 months. The DHA-enriched diet increased the volume of blood in the brain without changing blood flow, indicating improved circulation in the brain, and decreased the amount of vascular beta-amyloid deposition. TWD diet increased plaque burden in the hippocampus (the part of the brain required for memory formation).
Click here to view the study abstract.
DHA supplementation reduced accumulation of beta-amyloid fragments in the neuronal cells of mice
In this study reduced the intraneuronal accumulation of both amyloid-b (Abeta) and tau protein; combining DHA with n-6 fatty acids, either arachidonic acid or docosapentaenoic acid (DPAn-6), diminished the efficacy of DHA over a 12 month period. The authors observed that the reduction in soluble Abeta was attributable to a decrease in steady-state levels of presenilin 1 (mutations of this gene are associated with severe familial AD).
Click here to view the study abstract.
Omega-3 fatty acids may reduce cognitive decline in those with mild cognitive dysfunction
174 patients with AD, all stable and receiving an acetylcholine esterase inhibitor, were randomised to receive either a daily intake of omega-3 fatty acids (1.7 g of DHA and 0.6 g of EPA) or placebo for 6 months. Cognitive function was measured with the Mini Mental State Examination (MMSE) and the cognitive portion of the Alzheimer Disease Assessment Scale; at the end of the 6 months no significant differences in cognitive performance were seen between the two groups, however in a subgroup of patients with only mild cognitive dysfunction (scoring above 27 on the MMSE) a significantly slower rate of MMSE measured decline was observed in the omega-3 fatty acid-treated group compared with the placebo group; a similar reduction in rate of decline was observed between 6 and 12 months in patients with an equivalent profile in the placebo group when they were administered the omega-3 fatty acid supplement. These results suggests that omega-3 works optimally when administered in the early stages of cognitive decline.
Click here to view the study abstract.
DHA seen to have a protective effect on avoidance learning decline in rats infused with b-amyloid
This study investigated the relationship between the DHA-induced protection of learning deficit in a rat model of AD and changes in the fluidity of the fatty cell membrane surrounding neurons of the grey matter part of the brain (cerebral cortex). Oral administration of DHA increased the DHA content of the relevant cell membranes, lipid peroxidation (the process whereby free radicals, also known as reactive oxygen species, "steal" electrons from the fats in cell membranes, resulting in cell damage) decreased and cell membrane fluidity significantly increased; membrane fluidity was positively correlated with total avoidance learning. It is known that the less flexible the membrane, the less speedily messages will be transmitted between neurons and that the degree of fluidity directly reflects the fatty acid composition of the diet.
Click here to view the study abstract.
DHA rich diet decreased b-amyloid production in mice
Seven experimental diets with varying n-6/n-3-ratio, saturated and polyunsaturated fatty acid and cholesterol contents were fed to mice for 3-4 months beginning at 6 months of age; a typical Western diet with 40% saturated fatty acids and 1% of cholesterol increased, while diets supplemented with DHA decreased, Abeta levels compared to a regular (soy oil based) diet. Additionally DHA supplementation decreased the number of activated microglia (these are the central nervous system’s own immune cells) and increased exploratory behaviour in the mice. The favourable effect of DHA on Abeta production was verified in two different cell lines.
Click here to view the abstract.