Dementia Prevalence and Impact in Low Income Areas in South Africa
This project examines the nutritional status of older, low-income South Africans in relation to depression and dementia prevalence. Southern Africa has one of the lowest life expectancy rates in the world for both men (53 years) and women (54 years). This decline in longevity in SA is not only a result of communicable diseases (e.g. AIDS), but also a range of non-communicable diseases (NCDs). Due to the adoption of aspects of the Western diet—including high sugar and fat content—NCDs are on the rise, with cardiovascular disease accounting for 17% of all deaths in SA in 2000 (Bradshaw, 2003).
Mental illness is an understudied field in low and middle-income countries, despite the fact that it is predicted to be the largest contributor to the burden of disease in these countries by 2050. At present, access to management and care, including care for dementia sufferers, is not at an acceptable standard. International research shows that risk factors for both depression and dementia include elevated levels of an amino acid (homocysteine) in the bloodstream, which may be toxic to the brain. Homocysteine is a by-product of a metabolic cycle in protein digestion, specifically reliant on vitamins B12 and folic acid to reduce its concentration. Treatment with B vitamins, including folic acid and B12, has been shown in some studies to delay cognitive decline in the elderly (Durga, 2008; de Jager 2012). There have also been studies showing a decrease in depressive symptoms with folic acid. Depression has been shown to increase the rate of cognitive decline in those with preclinical Alzheimer's disease.
Thus, a study to determine a) the nutritional and homocysteine status and b) the prevalence of cognitive impairment and dementia with and without depressive symptoms would be valuable in South Africa. The study would indicate if there is a similar chance of intervention with simple nutrients to delay cognitive decline and alleviate symptoms of depression in older people in low and middle-income countries, as in the Western world where previous trials have been done (Smith et al, 2010). If the risk factors are as prevalent as in the Western World, then it would help to motivate the health services to increase spending on nutrient supplements as a cheap and effective intervention.
This study was initiated with a pilot study in the Cape Metropole with community dwelling volunteers 60 years of age and over. A food frequency questionnaire was adapted to include food items most likely to be consumed by the low income Xhosa-speaking population. Food items that contain B vitamins were shown in a set of cards to participants and quantities of those reported to be consumed were estimated. The B vitamin content was then calculated. Blood tests for homocysteine, folate and vitamin B12 were performed. The B vitamin intake was correlated with the blood levels measured. Cognitive performance was also tested with the Cognitive Screening Instrument for Dementia (CSID) translated into isiXhosa. The analysis and publication of these results is pending.
The tools from the pilot study were used in a large dementia prevalence study conducted in the Eastern Cape in a rural community. 1400 partiicpants and their informants were interviewed with the CSID and a brief food frequency questionnaire. Those who scored below the dementia cut-off on the test were invited to see a study nurse for medical follow-up, including mecical history, eyesight and mobility screening, blood sampling, HIV testing and screening for symptoms of depression. The prevalence data have been analysed and submitted for publication. Analysis of the blood test results is pending.