Yasmin Williams - HEALTH-WISELAST WEEK, I alluded to past research studies which suggested that hormone therapy with oestrogen may reduce the risk of Alzheimer's disease. The recent Women's Health Initiative (WHI) study, a randomised, controlled study, has challenged evidence suggesting that oestrogen therapy may protect the brain cells thus decreasing the risk of cognitive impairment (impairment of mental capacity) or dementia (mainly Alzheimer's).
The WHI found that oestrogen and progesterone increased the risk of cognitive impairment/ dementia in women 65 years and older and did not prevent cognitive changes. The average age of the women in the study was 71 years. It is not known whether the risk would be the same for women below 65 years and whether a particular subset of women was at risk.
Many point out that although the study findings are statistically significant, the risk to a particular individual is very, very small.
At present, most practitioners seem to agree that hormone replacement therapy should not be given as preventive medicine but for short term relief of unacceptable vasomotor symptoms, for example, hot flushes/flashes and at the lowest efficacious dosage.
The U.S. Food and Drug Administration (FDA) has advised that oestrogen and
progesterone combinations have never been approved for the prevention of cognitive impairment. The FDA indicated that the WHI data would be reviewed after which time there would be a final conclusion on the findings.
It must be highlighted that diet may be a healthy preventive strategy to decrease the risk of Alzheimer's. There is evidence to suggest that high levels of cholesterol in the brain tissue and the blood may be related to occurrence of Alzheimer's disease. Three prospective studies in Chicago/USA, New York/USA and Rotterdam in the Netherlands, as well as animal studies, provide some of the evidence.
Data from the Rotterdam Study, a population-based cohort study, suggests that the antioxidants vitamins C and E, obtained from food, not tablets, decreases the risk of Alzheimer's. Currently there is the Prevention of Alzheimer's Trial by Vitamin E/Selenium - PREADVISE prevention trial. This trial is an addition to the National Institute of Health's SELECT trial (cancer prevention trial). It seeks to find out if taking vitamin E and selenium tablets can help prevent cognitive impairment/memory loss and dementia.
In the Rotterdam Study and the Chicago Study, one fish meal a week was associated with a 60 per cent risk in the development of Alzheimer's. In cited case control studies, lower levels of omega-3-fatty acids (which is obtained from fish) have been found in patients with Alzheimer's as compared to control patients. There are no identifiable studies to indicate that taking a fish oil tablet a day will prevent Alzheimer's.
Scientists at the National Institute of Health/USA have found that in animal studies, mice (with Alzheimer like plaques) that had low levels of folic acid and the associated inverse increase in a chemical called homocysteine were unable to repair damaged brain cells unless they were fed a folate rich diet. Scientist have also found that persons with Alzheimer's tend to have low levels of folic acid and persons who have high levels of homocysteine tend to have twice the risk of developing Alzheimer's. Based on the findings of current research, there is now speculation that taking folic acid, either in the diet or as supplementation, could possibly protect from Alzheimer's disease.
At this point in time, despite the current research findings, we can only say that having a diet with adequate amounts of vitamins C, E, folic acid and omega-3-fatty acid but low in fat (especially unsaturated fat) may help to prevent or decrease the risk of Alzheimer's. Common sense suggests that until the additional research is done, each and everyone of us should have a balanced, healthy diet which would satisfy the above requirements.
Dr. Yasmin Williams is a Family Doctor and Public Health Specialist.
