Previous animal studies had shown that dietary n-3 polyunsaturated fatty acids improved brain functioning, but there was little information on how these fats affected AD.

To investigate this further, Dr Martha Clare Morris and colleagues, from the Rush-Presbyterian-St Luke’s Medical Center in Chicago, enrolled 815 subjects, aged between 65 and 94, who were initially unaffected by AD. The participants competed a dietary questionnaire and were followed for around four years.

Incident AD was diagnosed in a structural neurological examination using standardised criteria.

The team found that 131 subjects developed AD during the study. After adjusting for age and other risk factors, the scientists found that participants who consumed fish once or more a week had a 60 per cent decreased risk of developing AD compared to those that rarely or never ate it.

They also observed that the total intake of n-3 polyunsaturated fatty acids and docosahexaenoic acid was associated with a reduced risk of AD.

Dr Morris says, “Our findings suggest that consumption of fish (at least weekly), oil-based salad dressing and nuts may reduce the risk of AD.”

However, in an accompanying editorial Dr Robert Friedland, from the Case Western Reserve University School of Medicine in Cleveland, comments, “The beneficial effects of [fatty acids] from fish may be counterbalanced by toxins. Fish may contain dangerous levels of polychlorinated biphenyl and mercury from coal-fired power plants – especially methyl mercury.”


Reference: Morris et al, Archives of Neurology 2003;60:940-946

© HMG Worldwide 2003
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