Nutrition Missing from the Lancet’s Cognitive Footprint of Dementia Prevention
In leading medical journal The Lancet, Rossor and Knapp frame the challenge in reducing the disease burden of dementia as a “cognitive footprint”. As world populations age, there are concerns that the costs of treating and caring for people with dementia will be problematic. Via a “cognitive footprint” Rossor and Knapp attempt to bring attention to a wide range of activities that can preserve cognition over the lifespan.
The authors cite many behaviors, environments and interventions leading to improvements in cognition. Starting from pregnancy, maternal smoking, alcohol and drug use leads to poorer cognitive achievements, as does maternal perinatal illness. Education, both in early life and adulthood, is considered to be bi-directional, such that children with a greater cognitive capacity tend to complete more schooling successfully, and also that schooling can enhance cognition. For example, Banks and Mazzonna show that greater educational attainments in early life improve memory and executive function in old age. Bilingualism enhances cognition in old age, according to Bak and co-workers.
Infectious diseases such as neurocysticercosis from the tapeworm Taenia solium is the food-borne parasite that has the greatest effect on cognition. Other parasitoses have negative effects on the central nervous system (see review from Finsterer and Frank). Both improved hygiene and anti-helmetics can conserve cognitive potential, particularly in developing countries.
Aside from the potential for certain drugs used in pregnancy to affect the later cognitive potential of the unborn child, other medication may also affect cognition, both positively and negatively. For example, after concern that statins, widely used to prevent cardiovascular disease, cause memory loss, Swiger and colleagues found no effects on short-term measures of cognitive function, and a potential beneficial effect on long term cognitive function in a meta-analysis of clinical studies.
Exercise is one behavior that appears to consistently improve cognition in aging. Beydoun et al. found that physical exercise halved risk of Alzheimer’s disease. Even so, the authors caution that the benefits and risks of exercise on cognition have to be weighed against each other: in some sports, head injuries occur often enough to confer a risk of long term cognitive damage.
The approach suggested by Rossor and Knapp is well thought out and lists many ways that individuals, communities and governments can make changes to preserve cognition over the lifespan. Nevertheless, apart from a cursory mention of diet, the authors do not mention any ways in which nutrition can help us reach our cognitive potential and maintain it in old age. This is a great omission! Countless studies show the beneficial effects that preventing nutrient deficiencies has on brain function and measures of intellectual ability. Just browsing through our blog posts this year gives an overview of some of the effects:
· Treating maternal iodine deficiency is one of the easiest ways to avoid one of the most common causes of mental retardation in the world (July 22, 2015)
· Omega-3 fatty acids may affect stroke risk (July 8, 2015)
· Undernutrition is associated with mild cognitive impairment (June 23, 2015)
· Maternal iron deficiency can affect children’s later intellectual acheivements (June 12, 2015)
· Omega-3 levels in school children were associated with better reading ability and memory (May 14, 2015)
· The Mediterranean/DASH diet reduces risk of Alzheimer’s disease (April 23, 2015)
· Low vitamin E levels are associated with cognitive impairment in older adults (April 14, 2015)
· Folic acid supplementation reduced stroke risk (March 16, 2015)
Why did they leave it out? Perhaps it is the 1500-word limit on opinion pieces in the The Lancet meant that the nutrition section got the chop in the article. I often have trouble expressing a simple opinion into less than 500 words, and I can imagine that it is difficult to fit such a large and complex subject into such a low word count. This is a shame, as meeting nutritional recommendations throughout life should be highlighted as a cornerstone of helping people reach their intellectual potential. The "cognitive footprint" is maximized with good nutrition.
Rossor M, Knapp M. Can we model a cognitive footprint of interventions and policies to help to meet the global challenge of dementia? The Lancet. Published Online: 29 July 2015 doi:10.1016/S0140-6736(15)60248-3
Bak TH, Nissan JJ, Allerhand MM, Deary IJ. Does bilingualism influence cognitive aging? Ann Neurol. 2014 Jun;75(6):959-63. doi: 10.1002/ana.24158. Epub 2014 Jun 2. http://www.ncbi.nlm.nih.gov/pubmed/24890334
James Banks and Fabrizio Mazzonna. The Effect of Education on Old Age Cognitive Abilities: Evidence from a Regression Discontinuity Design. Econ J (London). 2012 May 1; 122(560): 418–448. Published online 2012 Apr 12. doi: 10.1111/j.1468-0297.2012.02499.x
Beydoun MA, Beydoun HA, Gamaldo AA, Teel A, Zonderman AB, Wang Y. Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC Public Health. 2014 Jun 24;14:643. doi: 10.1186/1471-2458-14-643. http://www.ncbi.nlm.nih.gov/pubmed/24962204
Finsterer J, Frank M. Parasitoses with central nervous system involvement. Wien Med Wochenschr. 2014 Oct;164(19-20):400-4. doi: 10.1007/s10354-014-0307-8. Epub 2014 Oct 9. http://www.ncbi.nlm.nih.gov/pubmed/25297698
Statins and cognition: a systematic review and meta-analysis of short- and long-term cognitive effects. Swiger KJ, Manalac RJ, Blumenthal RS, Blaha MJ, Martin SS. Mayo Clin Proc. 2013 Nov;88(11):1213-21. doi: 10.1016/j.mayocp.2013.07.013. Epub 2013 Oct 1. http://www.ncbi.nlm.nih.gov/pubmed/24095248