News reports of research into memory April 2003

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April 2003

Meal skipping protects the nerve cells of mice

Further to the study reported in January, a new mouse study suggests fasting every other day may protect brain neurons as well as or better than either vigorous exercise or caloric restriction. The mice were allowed to eat as much as they wanted on non-fasting days, and did not, overall, eat fewer calories than the control group. Their nerve cells however, proved to be more resistant to neurotoxin injury or death than nerve cells of both the calorie-restricted mice or the control group. Previous research has found that meal-skipping diets can stimulate brain cells in mice to produce a protein called brain-derived neurotrophic factor (BDNF) that promotes the survival and growth of nerve cells. The researchers are now investigating the effects of meal-skipping on the cardiovascular system in laboratory rats.
The study was published in the Proceedings of the National Academy of Sciences Online Early Edition the week of April 28, 2003. Full reference
http://www.eurekalert.org/pub_releases/2003-04/nioa-msh042403.php

Interactions with other races can impair mental capacity in the strongly prejudiced

A new approach on an old theme — the effect of stress on cognitive function. The study looked at the short-term effects of racial prejudice. White college students were assessed for racial bias and then had a conversation with either a black or white person. After the conversation, they were given the Stroop test (participants are presented with color words, which are either in the same color as they name, or not; they are required to respond on the basis of the color of the word, not the name. The test requires a surprising amount of concentration.) For those who had talked with a black person, the greater the amount of racial bias, the worse the student did on the Stroop test. This is assumed to be due to the stress caused by the interaction.
The study is to be published in the May issue of Psychological Science. Full reference
http://www.eurekalert.org/pub_releases/2003-04/pu-tpo043003.php

Prenatal exposure to alcoholaffects executive functioning in young children

A study of 316 four-year-old children whose mothers had used various combinations of cocaine, alcohol, and/or marijuana during pregnancy, found that children in the alcohol-exposed group performed significantly worse at an inhibition task than the children in the control group (no maternal use of such substances during pregnancy). This effect persisted even after controlling for prenatal drug exposure, postnatal environmental factors, and child verbal IQ, and suggests that children exposed prenatally to alcohol find it more difficult to inhibit inappropriate behaviors. This may partly explain why such children are at greater risk for social and academic problems. The subtle effect may not be noticeable in most children, but for those who operate at lower levels of functioning, the effect may make all the difference between coping and not. This effect occurred with prenatal alcohol exposure of less than one drink per day. In the United States, it is estimated that among women who know they are pregnant, 2% continue to drink at a moderate level and 5% continue to have at least two drinks per week.
The study was published in the April issue of Alcoholism: Clinical & Experimental Research. Full reference
http://www.eurekalert.org/pub_releases/2003-04/ace-efi040503.php

Long-lasting changes in attention and motor skills after heavy stimulant abuse

A study of 50 pairs of twins, in which one of each pair had a history of cocaine or methamphetamine abuse, and the other had no history of drug abuse, found that the twin with a history of stimulant abuse performed significantly worse on several tests of attention and motor skills than did the one who had never used drugs, even after at least a year had passed since any drugs had been taken. Abusers did, however, outperform their twin on visual vigilance, a test measuring the ability to pay attention over time.
The study was published in the March issue of Archives of General Psychiatry. Full reference
http://www.eurekalert.org/pub_releases/2003-04/niod-sot040903.php..

Cognitive impairment seen in heavy marijuana users who started using before 18

A study of 122 long-term heavy users of marijuana and 87 subjects who had used marijuana only a few times (control subjects), all of whom had refrained from any drug use 28 days prior to testing, found that those who had started using marijuana at age 17 or younger performed significantly worse on the tests assessing verbal functions such as verbal IQ and memory of word lists than did those who started using marijuana later in life or who had used the drug sparingly. There were virtually no differences in test results among the individuals who started marijuana use after age 17 and the control subjects. The subjects were all between 30 and 55 years of age.
The study was published in the March issue of Drug and Alcohol Dependence. Full reference
http://www.eurekalert.org/pub_releases/2003-05/niod-smu050203.php

New brain imaging technique

A new brain imaging technique (Voxel-based Lesion-Symptom Mapping (VLSM))has been developed. The technique will enable two different techniques – lesion-behavior mapping and functional magnetic resonance imaging – to be used together, helping researchers pinpoint the specific areas of the brain that are most crucial for normal functioning during critical brain activities.
The study was reported online on April 21 in Nature Neuroscience. Full reference
http://ucsdnews.ucsd.edu/newsrel/soc/dbatesvlsm.htm

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