Monday, April 19, 2010

The Multi-tasking Scatterbrain

Nobody should be surprised that people who multi-task a lot are easily distracted. It could well be that they multi-task a lot because they are so distractable and less able to focus.

A recent rigorous study of this matter evaluated a group of study participants, divided into those that were heavy multi-taskers and those that multi-tasked only infrequently. All participants were probably at the higher end of general mental capabilities, given that they were Stanford college students. Each participant was tested in a series of thinking tests to check for any difference in the way the two types of people processed information and disciplined their attentiveness.
  
Heavy multi-taskers were less able to sustain focus in the presence of distractions. The researchers concluded that light multi-taskers "find it easier to attentionally focus on a single task in the face of distractions."

The study did not directly examine ability to memorize, but there surely must be a significant difference, given that memory formation is enhanced by sustained attentiveness and focus. There may be some undiscovered benefits of multi-tasking, but memorizing cannot be one of them.

Nor is intelligent thought likely to benefit from multi-tasking. Several studies that I have summarized elsewhere show that intelligence correlates with working memory capacity, which under the best of circumstances is limited and easily over-loaded by multiple simultaneous informational input.

The study did not test whether distractibility is a cause or a consequence of multi-tasking behavior. But the data clearly support the notion that people whose work or study requires concentration should not multi-task.
There is also the potential problem that frequent multi-tasking could be teaching the brain to become more distractible.

Source:

Ophir, E., Nass,  C., and Wagner, A. D. 2009. Cognitive control in media multitaskers. Proceedings National Academy of Science. 106 (37): 15583-15587. doi/10.1073/pnas.0903620106

Sunday, April 18, 2010

Vitamin D: the wonder vitamin

Everybody knows that vitamin D is good for healthy bones. That is why they fortify milk with it. You may not know it is good for certain skin conditions, such is the one I have that appears every Winter when I don’t get enough sunlight, even though I live in Texas. Taking 2,000 IU vitamin D3 daily has stopped this problem. I read also that vitamin D stimulates the immune system. I am now surprised to learn it might be helpful for memory.

A research group in the United Kingdom, recognizing that many people are vitamin D deficient there because they don’t get much sunlight to help the skin generate vitamin D, pursued the question of why there are molecular receptors for vitamin D in the brain. What is that all about?

Some previous studies by other groups had shown vitamin D has protective effects on the brain and enhances its activity. Other studies had shown that low serum levels of the 25 (OH) form of vitamin D were associated with poor cognitive test performance among patients with mild Alzheimer disease, and a study of older adults revealed a positive correlation between 25(OH) D blood levels and scores on a mental function test.

This British study looked at a large population (3,133) of middle-aged and older men to evaluate the association between vitamin D levels and cognition. Specifically, the investigators tested blood levels of serum 25-hydroxyvitamin D in non-institutionalized European men, aged 40–79 years, and compared those levels with performance on three mental-function tests, one of which was a specific test of memory. High blood levels of vitamin D were associated with better performance on a test for analyzing complex visual images and a recognition memory test.

Studies like this are exceedingly complex, because there are many hard-to-control variables (the paper had more than 21 authors). Not surprisingly, depression, physical activity, physical performance, and smoking were all consistently associated with both cognitive test scores and 25(OH) D concentrations. Some mental-test scores, together with 25(OH)D levels, were additionally associated with drinking one or more alcoholic drink per week. Also, as expected, 25(OH) D levels varied markedly by season, peaking in the summer and reaching bottom in the winter.

After additional adjustments for age, education level, depression, basal metabolism, physical activity, physical performance, smoking, alcohol consumption, season, higher 25(OH) D concentrations were found to be associated more specifically with psychomotor speed and visual scanning.

Vitamin D exists in two common forms; vitamin D2 and D3. The form mainly produced in the skin and derived from natural dietary sources is vitamin D3, whereas the primary source of vitamin D2 is multivitamin preparations and some fortified foods. There have been conflicting reports as to whether vitamin D2 and vitamin D3 are equally effective at maintaining 25(OH) D levels,

Nobody knows why vitamin D affects brain function, but the existence of specific molecular receptors inside the nucleus of neurons cannot be dismissed. Possibilities include direct effects on promoting synthesis of the alertness-producing neurotransmitter, acetylcholine, or more indirect effects on intracellular calcium (calcium is a signaling molecule  in nerve cells). Other possible ways vitamin D might help brain function include its ability to stimulate synthesis of nerve growth factor.  Vitamin D is neuroprotective against stroke and, by its ability to attenuate neurotoxic insults, could have a major impact in preventing neurodegenerative diseases.  Vitamin D has the potential to increase glutathione which helps with detoxification and protection against free radical stress.

It is still an open question whether vitamin D helps memory. But I will keep taking my vitamin D3 to help my skin condition. Any benefit to my memory will be a much-appreciated bonus.


Source:

Lee, David M. et al. 2009. Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men. J. Neurol. Neurosurg. Psychiatry. 80:22-729. Doi: 10.1136/jnnp.2008.165720.

Friday, April 02, 2010

Resveratrol: the red wine magic chemical

I try not to get too excited about memory benefits of supplements. Certainly, I only have any level of faith in formal scientific studies that are well controlled and peer reviewed. I now think that resveratrol may be one of the few supplements that could have beneficial effects on brain function.

You no doubt have heard about the French red-wine drinkers, who are more healthy than they ought to be, given that they drink too much, exercise too little, and eat too much fat (as in goose liver and cheese). In trying to figure out how this can be, scientists have homed in on a major anti-inflammatory chemical in red wine, known as resveratrol. At this writing, over 2,000 scientific papers have been published. Don't worry, I am only going to tell you about a few. Most of the protective biological actions associated with resveratrol have been associated with its intrinsic radical scavenger properties and the protective effects that it confers on the heart.

Most of this research focuses on the compound's beneficial effects on heart and blood vessels and diabetes. The compound targets multiple enzymes in multiple organs. What I am summarizing here is recent research that suggests resveratrol might be beneficial for thinking ability in general and memory in particular.

A diabetes research group in Brazil recently reported a beneficial effect of resveratrol on diabetic rats. An earlier study by another group showed that resveratrol improved glucose metabolism and promoted longevity in diabetic mice. Other research groups had reported neuroprotective effects for resveratrol. The Brazil group focused on brain damage produced by diabetes. They induced diabetes in a group of rats, observing that this impaired their ability to memorize. The cause, as indicated by other studies, is that diabetes lowers the level of a major brain neurotransmitter that promotes alertness, attentiveness, and general cognitive function, acetylcholine. As an aside, the major treatment for Alzheimer's disease is Aricept, which enhances acetylcoline function. The Brazil group found that resveratrol suppressed activity of the enzyme that destroys acetylcholine, thus tending to restore more normal acetylcholine function. Resveratrol (in a modest rat dose of 10 and 20 mg/kg per day for 30 days) prevented the impairment of memory induced by diabetes.

Added to this finding about the brain enzyme, there are other reasons to think the anti-oxidant properties of resveratrol might be beneficial to the brain. The brain has more oxygen consumption than any bodily organ, about 20% of all the body's consumption. The brain therefore produces more free-radical damage, but the brain has especially low levels of antioxidant defense enzymes.

One recent study has revealed that resveratrol had protective effects against brain damage caused by a chemical that kills acetylcholine neurons. Injection of this toxin into the brain of rats impaired their memory performance in two kinds of maze tasks. The impairment was significantly reduced by repeated injection of resveratrol (10 and 20 mg/kg) pr day for 25 days, beginning four days before the toxin injection.
 
Another recent study examined the effect of dietary supplement on working memory in mice.  Groups of young adult and aged mice were put on a resveratrol-supplementd diet for four weeks before being injected with a cytokine to induce inflammation and accelerate aging. Mice were then tested for their ability to remember what they learned in a commonly used spatial memory task in a water maze. The dietary supplement significantly reduced memory impairment in the aged group, but not in the young adults. The lack of benefit in young adults was a little misleading, in that there was a "ceiling effect" in that the young adults, even though given cytosine, were already performing at near-mazimum levles. Cytosine had clear impairing effects in the contol aged mice, but much less so in the resveratrol-treated aged mice. In other words, aging makes an animal more susceptible to toxic chemicals, and thus there is more opportunity for any beneficial treatment to become manifest.

The memory studies have appeared only in the last year or so and are confined to laboratory animals. The beneficial effects may occur only in preventing damage, as with diabetes or other kinds of brain injury. Benefits may also be imperceptible in the young.

The open question is whether resveratrol will help cognitive function in humans, especially healthy humans.But you can be sure that research on humans will become intense. Positive memory-enhancing results in humans have alredy been published for consumption of blueberries, in which resveratrol is a major ingredient.

One of the first such randomized controlled trials of resveratrol effects on memory in normal older adults.has been launched in 2010 by Todd Manini and Steven Anton at the University of Florida's Institute of Aging.


What foods besides red grapes have resveratrol? The most likely other sources you would eat or drink are blueberries, cranberries, and peanuts. It is not likely that you could drink or eat enough of such substances to get enough resveratrol to do any good. Highly concentrated supplements are coming on the market. I haven't given up my two glasses of red wine each day, but I have started taking one of the supplements. I haven't seen any reports that these high doses of resveratrol are toxic.

Sources:

Abraham, J., and Johnson, R. W. 2009. Consuming a diet supplemented with resveratrol reduced infection-related neuroinflammation and deficits in working memory in aged mice. Rejuvenation research. 12 (6): 445-453.  DOI: 10.1089/rej.2009.0888

Harkiumar, K. B., and Aggarwal, B. B. 2008. Resveratrol.. A multitargeted agent fo age-associated chronic diseases. Cell Cycle 7:8, 1020-1035.

Kumar, A. et al. 2007. Neuroprotective effects of resveratrol against intracerebroventricular colchicine-induced cognitive imapirment and oxidative stress in rats. Pharmacology.79 (1): 17-26. DOI: 10.1159/000097511

Schmatz R, et al. 2009. Resveratrol prevents memory deficits and the increase in acetylcholinesterase activity in streptozotocin-induced diabetic rats. Eur J Pharmacol. 2009 May 21;610(1-3):42-8. Epub 2009 Mar 19.