Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 423

Mild cognitive impairment (MCI) describes cognitive changes that are serious enough to be noticed by the affected individual and their associates but not sufficiently severe enough to affect the ability to carry out regular daily activities. Those with MCI are at a greater risk of developing Alzheimer’s disease, the most common dementia.²⁰ However, MCI does not always lead to dementia. It can be reversible, as in the case of a medication side effect, or it can remain stable or even return to normal over time.

Because MCI can precede dementia, it has been the target of experimental interventions to delay conversion to dementia. Many factors are involved in dementia prevention, such as risk factor reduction and management of cardiovascular disease, stroke, and diabetes, as well as diet, exercise, cognitive engagement, and genomics.²⁰ Cohort studies suggest an important role for dietary patterns and specific foods and nutrients for the prevention of MCI and dementia²¹; however, evidence on the specific benefits of vitamin and mineral supplements is limited.

A recent Cochrane Review by McCleery et al.²² analysed whether individuals with MCI benefitted from treatment with vitamin or mineral supplements. They identified eight RCTs that examined B vitamins (vitamin B6, vitamin B12, and folic acid combined or folic acid alone), vitamin E, and vitamin E combined with vitamin C, as well as a study of one essential mineral (chromium). Levels of vitamin supplementation exceeded RDA levels and varied across studies. For the RCTs of B vitamins, none reported incidence of dementia, and there was little to no effect of the supplements (taken for 6 to 24 months) on episodic memory, executive function, speed of processing, or quality of life. However, one study indicated a slower rate of brain atrophy over two years. In the RCT of vitamin E, there was no effect regarding progression from MCI to Alzheimer's dementia during the three‐year study, and no effect on overall cognitive function, episodic memory, speed of processing, clinical global impression, functional performance, adverse events, or mortality. The quality of the design was low for both the single trial of combined vitamins E and C and the single trial of chromium. The trials were small in the case of chromium (n = 26) and had only a single cognitive outcome of interest, so the supplements' effects could not be confirmed. In summary, evidence is lacking for the benefits of these supplements for MCI.²² Although interest in vitamins, minerals, and overall dietary guidance for preventing cognitive decline and Alzheimer’s disease is high, evidence‐based recommendations cannot yet be made from the available science.^20,21,22