WASHINGTON – Higher intake of n-3 fatty acids may have a protective effect against cognitive impairment, according to data presented at the annual meeting of the Gerontological Society of America.
In a study of almost 1,000 people aged 65 and older, those with dementia had significantly lower plasma levels of n-3 fatty acids, said Antonio Cherubini, M.D., of the Institute of Gerontology and Geriatrics in Perugia, Italy.
The n-3 fatty acids are an important component of the neuronal membrane, influencing membrane fluidity and all the related functions, such as signal transduction and enzyme function. Fish–particularly fatty fish, such as mackerel and albacore tuna–are the primary source of n-3 fatty acids.
Dr. Cherubini presented data from the Aging in Chianti (InCHIANTI) study, a population-based trial conducted between 1998 and 2000 in the Chianti region of Italy.
The 935 volunteers were categorized as having normal cognition (725 subjects), cognitive impairment without meeting criteria for dementia (153 subjects), or dementia (57 subjects). Cognitive function was screened using the Mini-Mental State Examination. The subjects with age- and education-unadjusted scores lower than 26 on the examination underwent more detailed tests.
The diagnosis of dementia was made according to DSM-IV criteria. Plasma fatty acid levels were determined using gas chromatography.
Subjects with dementia had the lowest n-3 fatty acid plasma concentrations–as a percentage of total fatty acid plasma concentrations in mg/L–with a mean of 2.7%, compared with 3.0% for the cognitively impaired group and 3.2% for the normal cognition group.
Subjects with dementia had the highest plasma concentrations of saturated fatty acids–as a percentage of total fatty acid plasma concentrations in mg/L–with a mean of 31.4%, compared with 30.1% for the cognitive impairment group and 30.3% for the normal cognition group.
“Subjects in the second group–those who have cognitive impairment but not dementia–tended to have intermediate values in many of the fatty acids,” Dr. Cherubini said.
The finding of lower n-3 fatty acid plasma concentrations in subjects with dementia persisted even after adjusting for age, gender, education, smoking status, cholesterol and triacylglycerol levels, alcohol, fatty acid and total energy daily intakes, and total plasma levels of fatty acids.
The difference between normal subjects and those with mild cognitive impairment was no longer significant after adjustment, he said.
Previous studies have examined the relationship between n-3 fatty acid consumption and the development of dementia, but the results have been conflicting. This may be because the studies involved small sample sizes and relied on only one indicator of n-3 fatty acid status–intake or blood concentration–Dr. Cherubini said.