On the Menu: Nutrients’ role in preventing Alzheimer’s
Nutritional supplementation may help reduce the incidence of dementia, but more research is needed
Alzheimer’s disease: A recent Behaviour & Attitudes survey among a representative sample of 700 Irish adults (aged 50 years and over) revealed that a third of respondents believed a diagnosis of Alzheimer’s disease would be significantly more difficult to cope with than one of heart disease. Photograph: Getty Images
With an ageing world population and improvements in healthcare systems, more people will be diagnosed with chronic disease, including dementia.
This global epidemic can no longer be ignored and neglected, according to Alzheimer’s Disease International (ADI), a worldwide federation of Alzheimer associations. Currently, 44 million people worldwide live with dementia.
However, the future forecast is startling. It is estimated that by 2050 this figure will rise to 135 million. With one new case occurring every four seconds, dementia should be considered a public health priority in all countries.
Typically chronic and progressive by nature, dementia alters our ability to think, recall and behave. Performing everyday activities becomes challenging and often people face their worst fear – they lose their independence. This is not a normal part of ageing.
Dementia is caused by a number of different brain diseases, one of which is Alzheimer’s disease.
A recent Behaviour & Attitudes survey among a representative sample of 700 Irish adults (aged 50 years and over) revealed that a third of respondents believed a diagnosis of Alzheimer’s disease would be significantly more difficult to cope with than one of heart disease.
The survey confirmed strong levels of fear, stigma and uncertainty associated with the disease.
Nearly half of respondents believed that they would have to give up their careers if they were diagnosed with the early symptoms of the disease.
The majority said they would wait a number of months to see a GP if they noticed they were suffering from memory loss.
Getting older and having a family history of Alzheimer’s disease increase our risk of developing the disease.
It is also thought that modifiable lifestyle-related factors such as high blood pressure, high cholesterol levels, obesity and type 2 diabetes in midlife can increase our risk too.
Although the pathophysiology of Alzheimer’s disease is complex, there are three main characteristics of the condition – beta amyloid plaque formation, neurofibrillary tangles and the loss of brain synapses.
Amyloid plaques are found in the spaces between nerve cells and are a normal part of ageing. However, in Alzheimer’s disease they develop in cognitive areas and affect brain function.
Neurons in brain cells have an internal support structure partly made up of microtubules. A protein called tau helps stabilise microtubules.
In Alzheimer’s disease, tau changes, causing microtubules to collapse, and tau proteins clump together to form neurofibrillary tangles which interfere with brain function.
Lastly, the brain consists of billions of specialised neurones which communicate with each other through synapses. In Alzheimer’s disease, these synapses are damaged and lost, impairing brain function.
This loss of synapses is one of the key features of Alzheimer’s disease in the early stages and is associated with memory loss.
Evidence shows that people in the early stages of the disease have a reduced capacity to make use of certain nutrients such as uridine monophosphate (UMP), choline, and docosahexaenoic acid (DHA), all of which are needed to replenish synapses lost due to the disease.
A review of available research carried out by the ADI confirmed that when folate or vitamin B12 is deficient, homocysteine levels rise. High homocysteine levels are linked to an increased risk of cardiovascular disease.
There is also consistent evidence that high levels of homocysteine are associated with cognitive decline. Nutritional screening carried out by a qualified dietitian can help identify malnutrition and those at risk of deficiencies in B12 and in folate.
Research shows they have lower levels of key nutrients, including omega-3 fatty acids, B vitamins, and vitamins C and E, when compared with age-matched individuals without Alzheimer’s disease.
Patients may also have increased requirements for the nutrients like selenium.
Souvenaid is the first medical nutrition product designed to support synapse formation in early Alzheimer’s disease. This 125ml drink, produced by Nutricia Medical, was launched in April 2013. It includes omega-3 polyunsaturated fatty acids, uridine and choline, together with phospholipids and B vitamins.
These nutrients are naturally present in food, although the levels found in Souvenaid are difficult to achieve from diet alone.
Souvenaid must be used under medical supervision and it has been shown in a small number of clinical trials to improve episodic memory at this stage of the disease.
The trials indicated that taking Souvenaid once a day over 24 weeks improved the memory performance of people in the early stages of Alzheimer’s disease, as measured by functional tests of memory compared with the placebo group.
It may be particularly useful to those whose symptoms prevent them having a nutritionally adequate diet.
The Alzheimer’s Disease International emphasises in its report, Nutrition and Dementia , published in February 2014, the need for clear, consistent and independent evidence-based advice to support decision-making as to the suitability of nutritional supplements for those at risk of, or already living with, dementia.
It calls for more research into the following:
n The possibility that nutritional supplementation may be effective in reducing the incidence of dementia in people who are deficient in certain B vitamins such as vitamin B12 and folate.
n The effective components of a Mediterranean diet with respect to the prevention of dementia and progression of Mild Cognitive Impairment.
n The possibility that some forms of supplementation may yet be effective in altering the course of dementia, if targeted upon those who are deficient.
n The minimum effective dose of vitamin E as a treatment for clinical progression in dementia, and the balance of associated risks and benefits.
Paula Mee is lead dietitian in Medfit and a member of the Irish Nutrition and Dietetic Institute. Email firstname.lastname@example.org or tweet @paula_mee