Wellness Watch: Cognitive Health
May 1, 2010
Cognition is a combination of mental processes that includes the ability to learn new things, intuition, judgment, language and remembering. Dementia is characterized by the loss of or decline of these mental processes, specifically memory. Dementia is caused by various diseases and conditions that result in damaged brain cells. Alzheimer’s disease is the most common form of dementia.
A healthy adult brain has billions of nerve cells, or neurons, with long branching extensions connected at trillions of points. At these connections, called synapses, information flows in tiny chemical pulses released by one neuron and taken up by the receiving cell. Different strengths and patterns of signals move constantly through the brain’s circuits, creating the cellular basis of memories, thoughts and skills. With dementia, information transfer at the synapses begins to fail, the number of synapses declines and eventually cells die. For the most part, this is a natural part of the aging process.
Today’s maturing population defies aging, and thus, cognitive health is taking center stage for many Americans. Further, interest in cognitive health is expanding to younger populations, those in the 30 to 60 years range, with “prevention the best medicine” being their motto. Their desire to keep their brain sharp is keeping food, beverage and supplement manufacturers busy with developing so-called “brain foods.”
DHA drives innovation
The leading food ingredient marketed for cognitive health is docosahexaenonic acid (DHA), an omega-3 fatty acid. FDA only recognizes a qualified health claim for DHA (with eicosapentaenoic acid, also known as EPA) that states, “supportive but not conclusive research shows that consumption of EPA and DHA fatty acids may reduce the risk of coronary heart disease.” Currently, regulatory agencies do not accept that there is sufficient evidence for any of the other suggested benefits of DHA, including cognitive health. However, many believe a brain claim is not that far away.
The potential brain-boosting benefits of DHA have been reported by numerous studies, including scientists who spoke at the Alzheimer’s Association 2009 International Conference on Alzheimer’s Disease in Vienna. They reported that daily supplementation with DHA may improve both memory function and heart health in healthy older adults.
A new study published online in the Journal of Nutrition (doi:10.3945/jn.109.119578) shows that increased blood levels of DHA are associated with improved nonverbal reasoning and working memory in people between 35 and 54 years old, but intakes of two other omega-3 fatty acids fatty acids - alpha-linolenic acid (ALA) and EPA - were not.
“These findings suggest that DHA is related to brain health throughout the lifespan and may have implications for clinical trials of neuropsychiatric disorders,” wrote the researchers, led by Matthew Muldoon from the University of Pittsburgh. “Higher DHA was related to better performance on tests of nonverbal reasoning and mental flexibility, working memory and vocabulary. Furthermore, increasing levels of DHA were associated with improved mental function in a “generally linear” relationship.
“…research to date suggests that specifically, DHA may favorably affect cognitive performance and may do so throughout the life course,” they concluded.
In a separate study published in the American Journal of Clinical Nutrition (April 2010), researchers from the University of Cincinnati conducted a study on randomized healthy boys ages 8 to 10 years old, who either received a placebo or one of two doses of DHA (400 milligrams per day or 1,200 milligrams per day) for eight weeks. Relative changes in cortical activation patterns during sustained attention were determined by functional magnetic resonance imaging.
After eight weeks, erythrocyte membrane DHA composition increased significantly from baseline in both the low-dose (up 47%) and high-dose (up 70%) DHA groups, and dropped by 11% in the placebo group. During sustained attention, the subjects in both DHA groups had significantly greater changes in activation of the dorsolateral prefrontal cortex compared to the placebo group. Erythrocyte DHA composition was positively correlated with dorsolateral prefrontal cortex activation and inversely related with reaction time.
Other brainy ingredients
There are numerous other ingredients associated with cognitive health (see chart). Some are limited to dietary supplement applications, while others can be used in foods.
L-carnitine is a natural nutrient found in our body and in some foods. It is essential for transporting long-chain fatty acids into the mitochondria, where they are broken down and transformed into energy. Due to its important role in energy metabolism, it is not surprising that L-carnitine has been associated with cognitive health.
Phosphatidylserine (PS) is a natural phospholipid found in the brain. It is considered an important part of brain-cell membranes and has been shown to have a role in slowing, and even reversing, some forms of age-related cognitive deteriorations, such as short-term memory loss, and improving others, such as the ability to learn new tasks.
On May 13, 2003, FDA stated “based on its evaluation of the totality of the publicly available scientific evidence, the agency concludes that there is not significant scientific agreement among qualified experts that a relationship exists between PS and reduced risk of dementia or cognitive dysfunction.” FDA concluded that “most of the evidence does not support a relationship between PS and reduced risk of dementia or cognitive dysfunction, and that the evidence that does support such a relationship is very limited and preliminary.” FDA did, however, give qualified health claim status to PS, stating that “consumption of PS may reduce the risk of dementia in the elderly” and “consumption of PS may reduce the risk of cognitive dysfunction in the elderly.”
The sunshine vitamin - vitamin D - has also been linked to cognitive health. In a definitive critical review published in the Federation of American Societies for Experimental Biology (FASEB) Journal (April 2008), scientists at Children’s Hospital & Research Center Oakland ask whether there is convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction. Joyce McCann, assistant staff scientist, and Bruce Ames, senior scientist, conclude that there is ample biological evidence to suggest an important role for vitamin D in brain development and function, and that supplementation for groups chronically low in vitamin D is warranted.
Recently, there were two new European studies looking at vitamin D and cognitive function that reinforce the FASEB review. The first study, led by neuroscientist David Llewellyn of the University of Cambridge, assessed vitamin D levels in more than 1,700 men and women from England, aged 65 or older. Subjects were divided into four groups based on vitamin D blood levels: severely deficient, deficient, insufficient (borderline) and optimum, then tested for cognitive function.
The scientists found that the lower the subjects’ vitamin D levels, the more negatively impacted was their perform¬ance on a battery of mental tests. Compared with people with optimum vitamin D levels, those in the lowest quartile were more than twice as likely to be cognitively impaired.
A second study, led by scientists at the University of Manchester in England, looked at vitamin D levels and cognitive performance in more than 3,100 men aged 40 to 79 in eight different countries across Europe. The data show that those people with lower vitamin D levels exhibited slower information-processing speed. This correlation was particularly strong among men older than 60 years.
These studies strongly suggest that low levels of vitamin D are associated with cognitive impairment; however, research needs to be conducted to see if high or optimum intake levels will lessen cognitive losses. It is also unclear if giving vitamin D to those who lack it will help them regain some of these high-level functions.
Dairy foods are already being enhanced with vitamin D and DHA. There is potential to include other cognitive health ingredients, adding brain food to dairy’s growing list of health and wellness benefits.
Food Ingredients Associated with Improving Cognitive Function
Docosahexaenonic Acid (DHA)