The Same Old Song

Preventing dementia: the good news and the bad from ICAD 2010

The numbers are overwhelming. There are over five million people in the US with dementia today, and that number may triple over the next 40 years. The costs of dementia to the US economy are already immense, with estimates over $150 billion annually. With all those cases coming down the line, how are we going to pay for it all? Well, there’s good news from the Alzheimer’s Association International Conference on Alzheimer’s Disease 2010 (ICAD), a gathering of more than 5000 researchers and clinicians from around the world, held in Hawaii from July 10-15, 2010: we may not need to face the full costs implied by those overwhelming numbers. The bad news is that we’ve heard the messages before, and they’re not easy to implement. 

In ICAD’s opening plenary session on July 11, Dr. Kristine Yaffe from the University of California at San Francisco reviewed the evidence that there are modifiable risk factors with the potential of reducing the risk for dementia. She presented an overview of similar material in the Archives of Neurology in 2009 with her colleague, Laura Middleton [1]. Dr. Yaffe identified several areas of focus for dementia prevention. Chief among these were vascular risk factors like hypertension, dyslipidemia, and diabetes. While these problems have long been associated with increased risk for dementia due to cerebrovascular disease (like multi-infarct dementia), there is growing evidence that these illness states also magnify the risk for dementia with Alzheimer’s disease pathology. She presented data supporting the argument that insulin resistance and obesity accelerate cognitive aging. In contrast, she also reviewed the literature suggesting that regular cognitive and physical activity can prevent or improve cognitive decline among older adults.

Several researchers provided updated evidence on these topics at a symposium on prevention that immediately followed the plenary session. Sherry Willis from the University of Washington presented results from the ACTIVE study which involved 2832 volunteers with a mean age of 73.6 [2]. Individuals received cognitive training in one of three randomly assigned cognitive domains (memory, reasoning, or speed of processing). When compared to controls, benefits of the training remained evident for 5 years. “Booster training” in reasoning or speed of processing provided additional benefit. Members of all three groups reported less decline in instrumental activities of daily living at the 5-year time point, but this was statistically significant only for the reasoning training group. In his presentation, Carl Cotman of the University of California at Irvine reviewed the growing body of evidence from animal models that indicates how physical exercise can lead to improved learning [3]. Exercise induces Brain-Derived Neurotrophic Factor (BDNF), along with other growth factors; these factors appear to induce beneficial cellular effects including neurogenesis and synaptic plasticity. Exercise may also improve neuronal energy production and reduce the inflammation associated with aging. Interestingly, exercise results in improved learning even in transgenic mouse models with extensive Alzheimer pathology, suggesting that the benefits of physical activity may not be restricted to dementia prevention alone but rather might be available even to patients with existing Alzheimer’s disease. The role of dietary factors in dementia prevention was presented by Martha Morris from Rush University [4]. Though deficiencies in micronutrients seem to be associated with dementia risk, further supplementation in the presence of adequate vitamin levels does not appear to convey further protection. She noted that diets low in vitamin E and high in saturated and trans-fats were associated with higher Alzheimer’s risk, and that consumption of fish once or more weekly may be protective against cognitive decline and Alzheimer’s disease. Maybe that old wives’ takle about fish being “brain food” isn’t a wives’ tale after all.

So, this is great news. We have clear evidence of things that any of us can do (or recommend) to reduce the risk of cognitive decline and developing Alzheimer’s disease as we grow older. What’s the down side? The effects are generally difficult to demonstrate in clinical trials with people, perhaps because there is already so much variability in what we do and eat, so we may never know – for sure – how beneficial these interventions might be.

There’s a bigger, and more practical, problem though. There’s really no news at all. Health care providers have been chanting the same mantra for a generation: Eat right, lose weight, exercise regularly. If preventing a stroke or a heart attack hasn’t been motivation enough for people to do these things, does adding Alzheimer’s disease prevention to the mix of good things they do really going to make a big difference? Who knows? But, at least we have another verse to add to that same old song.

Middleton LE, Yaffe K. Promising Strategies for the Prevention of Dementia. Arch Neurol 2009;66:1210-15. (http://www.ncbi.nlm.nih.gov/pubmed/19822776)

Willis S. Long term effects of cognitive training. Alzheimer’s and Dementia 2010;6(Suppl. 1):S63-4 (Abstract) (http://download.journals.elsevierhealth.com/pdfs/journals/1552-5260/PIIS155252601000302X.pdf)

Cotman C. Exercise and prevention of dementia. Alzheimer’s and Dementia 2010;6(Suppl. 1):S64 (Abstract) (http://download.journals.elsevierhealth.com/pdfs/journals/1552-5260/PIIS1552526010003043.pdf)

Morris, M. Dietray factors that may prevent dementia. Alzheimer’s and Dementia 2010;6(Suppl. 1):S64 (Abstract) (http://download.journals.elsevierhealth.com/pdfs/journals/1552-5260/PIIS1552526010003067.pdf)

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