US: New report finds no conclusive evidence that interventions prevent dementia

Additional research is needed to further understand and gain confidence in the effectiveness of the three interventions, the report concludes.

“Even though clinical trials have not conclusively supported the three interventions discussed in our report, the evidence is strong enough to suggest the public should at least have access to these results to help inform their decisions about how they can invest their time and resources to maintain brain health with ageing,” said Alan Leshner, chair of the committee that wrote the report.

Despite an array of advances in understanding cognitive decline and dementia, the available evidence on interventions derived from randomised controlled trials remains relatively limited and has significant shortcomings.

Based on all the available evidence, however, the report concludes that three classes of interventions can be described as supported by encouraging but inconclusive evidence. These are:

• cognitive training - which includes programmes aimed at enhancing reasoning and problem solving, memory, and speed of processing - to delay or slow age-related cognitive decline
• blood pressure management for people with hypertension - to prevent, delay, or slow clinical Alzheimer’s-type dementia
• increased physical activity - to delay or slow age-related cognitive decline.

Cognitive training has been the object of considerable interest and debate. Good evidence shows that cognitive training can improve performance on a trained task, at least in the short term.

However, debate has centred on evidence for long-term benefits and whether training in one domain, such as processing speed, yields benefits in others, such as in memory and reasoning, and if this can translate to maintaining independent living.

Evidence from one randomised controlled trial suggests that cognitive training delivered over time and in an interactive context can improve long-term cognitive function. However, results from other randomized controlled trials that tested cognitive training were mixed.

Managing blood pressure for people with hypertension, particularly during midlife - generally ages 35 to 65 years - is supported by encouraging but inconclusive evidence for preventing, delaying, and slowing clinical Alzheimer's-type dementia, the committee said.

The AHRQ systematic review found that the pattern of randomised controlled trials results across different types of physical activity interventions provides an indication of the effectiveness of increased physical activity in delaying or slowing age-related cognitive decline, although these results were not consistently positive.

Read more on http://www.nationalacademies.org/dementia