Mediterraan dieet,
meeroken en de mentale achteruitgang*
Uit twee studies blijkt het verband tussen roken, een mediterraan dieet en al dan niet een mentale achteruitgang. Regelmatig meeroken geeft volgens de ene studie 44% meer kans op een duidelijke mentale achteruitgang en daardoor een veel grotere kans op dementie of de ziekte van Alzheimer. Van de bijna 5.000, niet rokende deelnemers werden monsters genomen van het speeksel om de hoeveelheid nicotine
vast te stellen. Uit een tweede studie blijkt dat een mediterraandieet de kans op vroege dementie met 28% verlaagd. Voor zij die al een vroege dementie hebben reduceert een
mediterraandieet de kans op de ziekte van Azheimer wel met 48%.
Second-hand Smoke Linked To Cognitive Impairment
Exposure to second-hand smoke could increase the risk of developing dementia and other forms of cognitive impairment, according to research published by Dr David Llewellyn from the University of Cambridge and his
collaborators.
The research, published today in the British Medical Journal, highlighted a 44% increase in risk of cognitive impairment when exposed to high levels of second-hand smoke.
Previous studies identified active smoking as a risk factor for cognitive impairment and dementia. However, this is the first large-scale study to conclude that second-hand smoke exposure could lead to dementia and other neurological problems in adults. (Previous findings suggested that second-hand smoke exposure could impair cognitive development in children and adolescents.)
The research, led by Dr Llewellyn, used saliva samples from nearly 5000 non-smoking adults over the age of 50. By measuring levels of cotinine (a by-product of nicotine) in their saliva and taking a detailed smoking history, the researchers were able to assess levels of exposure to second-hand
smoke.
A range of neuropsychological tests were then used to assess aspects of brain function such as verbal memory (recalling words immediately and after a delay), numerical calculations, time orientation, and verbal fluency (naming as many animals as possible in one minute). These results were added together to provide a global score for cognitive function, and those whose scores were in the lowest 10 per cent were subsequently identified as suffering from cognitive impairment.
From their results they concluded that exposure to second-hand smoke may be linked to an increased chance of developing cognitive impairment, including dementia. The authors proposed a number of possible explanations for why exposure to second-hand smoke may increase the odds of dementia, including an increased risk of heart disease and stroke which are known to increase the risk of cognitive impairment and dementia.
Dr Llewellyn commented on the research, "We have conducted the first study to examine the association between second-hand smoke exposure and cognitive impairment in elderly non-smokers.
"Our results suggest that inhaling other people's smoke may damage the brain, impair cognitive functions such as memory, and make dementia more likely. Given that passive smoking is also linked to other serious health problems such as heart disease and stroke, smokers should avoid lighting up near non-smokers. Our findings also support calls to ban smoking in public
places."
1. The paper 'Exposure to secondhand smoke and cognitive impairment in non-smokers: national cross sectional study with continue measurement' will be published online at the British Medical Journal's website: http://www.bmj.com
2. The paper is accompanied by an editorial by Dr Mark Eisner from the University of California.
University of Cambridge, The Pitt Building Trumpington Street, Cambridge, Cambridge CB2 1RP United Kingdom
University of Cambridge
Mediterranean Diet Linked To Lower Risk Of Cognitive Impairment
Researchers in the US found that people whose diet is closer to a Mediterranean diet are at lower risk of developing MCI or Mild Cognitive Impairment (a stage between normal aging and dementia) and also have a reduced risk of MCI turning into Alzheimer's
disease.
The study was the work of Dr Nikolaos Scarmeas and colleagues at Columbia University Medical Center, New York and is published in the
Archives of Neurology, one of the JAMA/Archives journals.
Previous studies have found that sticking to a Mediterranean diet may protect people from Alzheimer's disease, but not much is known about its possible ties with
MCI.
A Mediterranean diet is high in fish, vegetables, legumes (beans and lentils), fruits, cereals and unsaturated fatty acids, and low in dairy products, meat and saturated fats, plus moderate amounts of alcohol.
For the study, the researchers asked 1,875 people to fill in questionnaires about their food consumption between 1992 and 1999. From the responses, the researchers then calculated a score for the extent to which each person's food intake most closely resembled a Mediterranean
diet.
At the start of the study, 1,393 of the participants had no cognitive problems and 482 of them had MCI, and they were all examined, interviewed and screened for
MCI.
The results showed that:
· Over an average follow up period of 4.5 years, 275 of the 1,393 participants without MCI developed the
condition.
· Comparing the one third with the lowest scores for Mediterranean diet adherence with the one third that had the highest scores, showed that having a high score was linked to a 28 per cent lower risk of developing
MCI.
· The middle third had a 17 per cent lower risk.
· Among the 482 participants who had MCI at the start, 106 developed Alzheimer's over an average follow up of 4.3
years.
· Among these participants, sticking to a Mediterranean diet was linked with a lower risk of MCI converting to
Alzheimer's.
· In this group, the one third of participants with the highest scores for Mediterranean diet adherence had a 48 per cent lower risk of developing Alzheimer's compared to the one third with the lowest scores.
· The middle third had a 45 per cent lower risk.
The authors concluded that:
" Higher adherence to the MeDi [Mediterranean diet] is associated with a trend for reduced risk of developing MCI and with reduced risk of MCI conversion to AD [Alzheimer's disease]."
They also wrote that more studies were needed to confirm these findings.
Speculating on their findings, they suggested that the Mediterranean diet may improve levels of cholesterol and blood sugar, as well as keep blood vessels healthier. It may also reduce inflammation. All these factors have been linked to MCI. They said that individual foods in the Mediterranean diet are also linked to lower risk of MCI. Examples of such foods
include:
"Alcohol, fish, polyunsaturated fatty acids (also for age-related cognitive decline) and lower levels of saturated fatty acids," they wrote.
Alzheimer's is the most common form of dementia, which is a general term for loss of memory and other intellectual skills that impair quality of life. Alzheimer's is a progressive and fatal brain disease that destroys brain cells, resulting in decline of memory, thinking and behaviour that eventually stops people from being able to work and have an independent life; their quality of life gradually diminishes as the disease progresses.
According to the Alzheimer's Assocation (US), the disease is the sixth leading cause of death among Americans.
"Mediterranean Diet and Mild Cognitive Impairment.
Nikolaos Scarmeas; Yaakov Stern; Richard Mayeux; Jennifer J. Manly; Nicole Schupf; Jose A. Luchsinger.
Arch Neurol. Vol. 66 No. 2, pp 216-225, 2009.
Sources: Journal abstract, JAMA/Archives press release, Alzheimer's Association. (Maart
2009)
