-
1.
Omega-6 to omega-3 fatty acid ratio and higher-order cognitive functions in 7- to 9-y-olds: a cross-sectional study.
Sheppard, KW, Cheatham, CL
The American journal of clinical nutrition. 2013;(3):659-67
-
-
Free full text
-
Abstract
BACKGROUND Biochemical and behavioral evidence has suggested that the ratio of n-6 (omega-6) to n-3 (omega-3) could be an important predictor of executive function abilities in children. OBJECTIVE We determined the relation between the ratio of n-6 to n-3 and cognitive function in children. We hypothesized that children with lower ratios of n-6 to n-3 fatty acids would perform better on tests of planning and working memory. DESIGN Seventy 7- to 9-y-old children completed three 24-h diet recalls and a subset of the Cambridge Neuropsychological Test Assessment Battery. Parents provided information on their demographics and children's diet histories. RESULTS Mean n-3 and mean n-6 intakes were related to the mean time spent on each action taken in the planning problem. The ratio of n-6 to n-3 significantly predicted performance on the working memory and planning problems. There was a significant interaction between the ratio and fatty acid intake; when children had high ratios, a higher intake of n-3 fatty acids predicted a better performance on the planning task than when children had lower n-3 intakes. When children had low ratios, a lower intake of n-3 and lower intake of n-6 predicted better performance than when intakes were higher. CONCLUSIONS The relation between cognitive abilities and the ratio of n-6 to n-3 may be mediated by an enzymatic affinity for n-3 fatty acids. The ratio of n-6 to n-3 should be considered an important factor in the study of fatty acids and cognitive development. This trial was registered at clinicaltrials.gov as NCT01823419.
-
2.
Practice effects in a longitudinal, multi-center Alzheimer's disease prevention clinical trial.
Abner, EL, Dennis, BC, Mathews, MJ, Mendiondo, MS, Caban-Holt, A, Kryscio, RJ, Schmitt, FA, , , Crowley, JJ, ,
Trials. 2012;:217
Abstract
BACKGROUND Practice effects are a known threat to reliability and validity in clinical trials. Few studies have investigated the potential influence of practice on repeated screening measures in longitudinal clinical trials with a focus on dementia prevention. The current study investigates whether practice effects exist on a screening measure commonly used in aging research, the Memory Impairment Screen (MIS). METHODS The PREADViSE trial is a clinical intervention study evaluating the efficacy of vitamin E and selenium for Alzheimer's disease prevention. Participants are screened annually for incident dementia with the MIS. Participants with baseline and three consecutive follow-ups who made less than a perfect score at one or more assessments were included in the current analyses (N=1,803). An additional subset of participants with four consecutive assessments but who received the same version of the MIS at baseline and first follow-up (N=301) was also assessed to determine the effects of alternate forms on mitigating practice. We hypothesized that despite efforts to mitigate practice effects with alternate versions, MIS scores would improve with repeated screening. Linear mixed models were used to estimate mean MIS scores over time. RESULTS Among men with four visits and alternating MIS versions, although there is little evidence of a significant practice effect at the first follow-up, mean scores clearly improve at the second and third follow-ups for all but the oldest participants. Unlike those who received alternate versions, men given the same version at first follow-up show significant practice effects. CONCLUSION While increases in the overall means were small, they represent a significant number of men whose scores improved with repeated testing. Such improvements could bias case ascertainment if not taken into account.
-
3.
Effects of acute tryptophan depletion on cognition, memory and motor performance in Parkinson's disease.
Scholtissen, B, Verhey, FR, Adam, JJ, Prickaerts, J, Leentjens, AF
Journal of the neurological sciences. 2006;(1-2):259-65
Abstract
BACKGROUND Parkinson's disease (PD) is a neuropsychiatric disease, which is not only characterized by motor symptoms, but also by cognitive and psychiatric symptoms. It is hypothesized that some of the non-motor symptoms are related to the serotonergic deficiency that is present in PD. AIM: To study the influence of serotonin on cognition, memory and motor performance in PD. METHODS In a double blind, randomized, placebo-controlled, cross-over design, the effect of acute tryptophan depletion (ATD) on the Visual Verbal Learning Task (VVLT), the Concept Shifting Task (CST), Simple Reaction Time Task (SRT), Finger Precuing Task (FPT) and the motor section of the Unified Parkinson's Disease Rating Scale (UPDRS, Section 3) was investigated in 15 PD patients in early stages of their disease and 15 healthy volunteers, matched for age, sex and educational status. RESULTS With the exception of the absence of a differential effect for PD patients with the long interval of the SRT, ATD produced similar effects in PD patients and control subjects on all tasks. These included impairment of delayed recall and delayed recognition on the VVLT, and improved SRT and FPT for 'short intervals'. The UPDRS in patients remained unaffected after ATD. CONCLUSION Serotonin does not appear to play a disease-specific role in cognition and reaction time in early stage PD patients, nor does acute reduction of cerebral serotonin levels affect motor symptoms in a clinically relevant way.
-
4.
Diet rich in alpha-lactalbumin improves memory in unmedicated recovered depressed patients and matched controls.
Booij, L, Merens, W, Markus, CR, Van der Does, AJ
Journal of psychopharmacology (Oxford, England). 2006;(4):526-35
Abstract
Depression is associated with reduced brain serotonin (5-hydroxytryptamine; 5-HT) function and with cognitive dysfunctions. A diet rich in alpha-lactalbumin protein has been found to increase the ratio tryptophan /large neutral amino acids (Trp/SigmaLNAA), and to improve cognitive functioning in individuals with high neuroticism scores. Since cognitive dysfunctions sometimes persist after remission of depression, the present study investigated the effects of alpha-lactalbumin-enriched diet on cognition in recovered depressed patients. Twenty-three recovered depressed patients and 20 healthy matched controls without a history of depression consumed meals rich in alpha-lactalbumin or casein protein in a double-blind crossover design. Mood, cognitive function and plasma amino acids were assessed at both sessions before and after dietary intake. Alpha-lactalbumin protein had no effect on mood, but improved abstract visual memory and impaired simple motor performance. These effects were independent of history of depression. Supplements of lactalbumin may be useful for nutrition research in relation to age- or disease-related memory decline. The present findings should be further examined in different (e.g. medicated) samples. The long-term effects of alpha-lactalbumin should also be investigated.
-
5.
The influence on cognition of the interaction between the macro-nutrient content of breakfast and glucose tolerance.
Nabb, S, Benton, D
Physiology & behavior. 2006;(1):16-23
Abstract
Previously it has been found that both missing breakfast and having poorer glucose tolerance were associated with better memory. The present study therefore examined the impact of eight breakfasts, in a factorial design, that contained either high or low levels of carbohydrate, fat or protein. The meals were designed to vary the rate of release of glucose into the blood stream. Memory, reaction times and vigilance were assessed 30, 75 and 120 min following breakfast. Using fasting blood glucose levels as a measure of glucose tolerance, better memory was found to be associated with better glucose tolerance and the consumption of meals that more slowly release glucose into the blood. The effects of the meals on reaction times and vigilance were opposite to those with memory in that higher levels of blood glucose tended to be associated with better performance. It was concluded that individual differences in glucose tolerance interact with the glycaemic load of a meal to influence cognitive functioning.
-
6.
Preliminary evidence of attenuation of the disruptive effects of the NMDA glutamate receptor antagonist, ketamine, on working memory by pretreatment with the group II metabotropic glutamate receptor agonist, LY354740, in healthy human subjects.
Krystal, JH, Abi-Saab, W, Perry, E, D'Souza, DC, Liu, N, Gueorguieva, R, McDougall, L, Hunsberger, T, Belger, A, Levine, L, et al
Psychopharmacology. 2005;(1):303-9
Abstract
RATIONALE Some of the behavioral consequences of deficits in N-methyl-D-aspartate (NMDA) glutamate receptor function are thought to arise from the disinhibition of cortical glutamatergic circuitry. OBJECTIVE This study evaluated whether pretreatment with a drug that reduces glutamatergic activation, the group II metabotropic glutamate receptor (mGluR) agonist, LY354740, reduced the cognitive effects of the NMDA glutamate receptor antagonist, ketamine, in healthy human subjects. METHODS Nineteen healthy human subjects completed 3 test days during which LY354740 (matched placebo, 100 mg, 400 mg) was administered under double-blind conditions 4 h prior to the single-blind intravenous administration of saline and 5.7 h prior to ketamine administration (bolus of 0.26 mg/kg over 1 min, infusion of 0.65 mg/kg per hour for 100 min). Thus on each test day each subject received a single dose of LY354740 (or its matched placebo) and both saline and ketamine infusions. RESULTS Ketamine impaired attention, working memory, and delayed recall. It also produced positive and negative symptoms, perceptual changes, and dysphoric mood. LY354740 did not have a significant effect on working memory on the placebo day; however, it produced a significant dose-related improvement in working memory during ketamine infusion. CONCLUSIONS These data provide preliminary and suggestive evidence that LY354740 or other group II mGluR agonists might play a role in treating working memory impairment related to deficits in NMDA receptor function.
-
7.
Memory function in women with premenstrual complaints and the effect of serotonergic stimulation by acute administration of an alpha-lactalbumin protein.
Schmitt, JA, Jorissen, BL, Dye, L, Markus, CR, Deutz, NE, Riedel, WJ
Journal of psychopharmacology (Oxford, England). 2005;(4):375-84
Abstract
Serotonergic hypofunction may underlie at least part of the symptoms that are experienced by women with premenstrual complaints, including memory deficits. In the current study we investigated changes in memory functions in the premenstrual phase compared to the early postmenstrual phase in 16 women with premenstrual complaints. In addition, the effect of an acute serotonergic stimulation by administration of an alpha-lactalbumin protein on premenstrual memory performance was assessed using a double-blind placebo-controlled crossover design. It was found that both short-term and long-term memory for words (30-word learning task) and abstract figures (abstract visual learning task) were mildly impaired in the premenstrual phase. Administration of alpha-lactalbumin during the premenstrual phase could only partially attenuate the memory performance decrements that are seen in the premenstrual phase. Specifically, alphalactalbumin improved long-term memory for abstract figures, but not for words. There were no effects of menstrual phase or alpha-lactalbumin on planning functions (computerized Tower of London). The data suggest that serotonergic hypofunction may play a role in premenstrual memory decline, but serotonergic mechanisms cannot fully account for observed cognitive changes in the premenstrual phase.
-
8.
Effects of N-PEP-12 on memory among older adults.
Crook, TH, Ferris, SH, Alvarez, XA, Laredo, M, Moessler, H
International clinical psychopharmacology. 2005;(2):97-100
Abstract
N-PEP-12 is a derivative of cerebrolysin, a brain-derived neuropeptide compound that has been approved for the treatment of Alzheimer's disease (AD) in more than 30 countries. N-PEP-12 is much less potent than cerebrolysin but it can be administered orally whereas the parent compound must be administered through multiple intravenous infusions. This study was undertaken to determine whether N-PEP-12 is effective in improving memory and other cognitive abilities among healthy older adults who have experienced 'normal' age-related memory loss. Subjects were 54 males and females, aged 50 years and older, who presented both subjective and objective evidence of memory loss since early adulthood. The study was a fully randomized, double-blind comparison of N-PEP-12 and placebo. Cognitive assessments were performed at baseline and following 30 days of treatment. The primary outcome measure was the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-cog) Memory score, with the Syndrom Kurz Test (SKT) test, digit cancellation, digit span, verbal fluency and clinical ratings as secondary outcomes. N-PEP-12 treated subjects performed better than placebo-treated subjects on the ADAS-cog Memory score, the SKT, clinical ratings and some, but not other tests. N-PEP-12 may be an effective treatment for memory loss in healthy older adults.
-
9.
Selective effects of acute serotonin and catecholamine depletion on memory in healthy women.
Harrison, BJ, Olver, JS, Norman, TR, Burrows, GD, Wesnes, KA, Nathan, PJ
Journal of psychopharmacology (Oxford, England). 2004;(1):32-40
Abstract
There is converging evidence that brain serotonin and dopamine may selectively modulate learning and memory in humans. However, this has not been directly demonstrated. In the current study, we used the method of amino acid precursor depletion to explore the effects of low serotonin and catecholamine function on memory in healthy female volunteers. Participants completed three experimental sessions: (i) tryptophan depletion (TD to lower 5-HT); (ii) tyrosine and phenylalanine depletion (TPD to lower catecholamines); and (iii) a balanced control condition (Bal). All testing was conducted in a double-blind, placebo-controlled, crossover design. Cognitive and mood assessments were performed at baseline and 5 h after ingesting the amino acid mixture. Consistent with previous studies, TD impaired declarative memory consolidation on a structured word-learning task, while TPD, acting to lower brain dopamine availability, impaired spatial working memory. No secondary deficits were observed on measures of attention, short-term memory or subjective mood state. These findings suggest that low brain serotonin versus dopamine selectively impairs memory performance in humans. This may shed light on the role of these neurotransmitters in disorders that are characterized by significant memory impairment.
-
10.
Variation in catechol-o-methyltransferase val158 met genotype associated with schizotypy but not cognition: a population study in 543 young men.
Stefanis, NC, Van Os, J, Avramopoulos, D, Smyrnis, N, Evdokimidis, I, Hantoumi, I, Stefanis, CN
Biological psychiatry. 2004;(7):510-5
Abstract
BACKGROUND Increased catechol-O-methyltransferase activity associated with variation in catechol-O-methyltransferase valine158 methionine genotypes may result in reduced dopamine neurotransmission in the prefrontal cortex and thus contribute to the poor performance of frontally mediated cognitive tasks and the occurrence of associated negative symptoms observed in patients with schizophrenia; however, reported associations between catechol-O-methyltransferase valine158 methionine genotypes and measures of cognition have not been consistent. METHODS Catechol-O-methyltransferase genotyping, measures of schizotypy, cognitive measures of memory and attention, as well as the antisaccade eye movement task, a measure sensitive to prefrontal cortical function, were obtained in a sample of 543 young men representative for that age group (mean age 21 years). RESULTS None of the cognitive measures was associated with catechol-O-methyltransferase valine158 methionine genotypes; however, there was an effect of high-activity allele loading on schizotypy, in particular the negative and disorganization dimensions. CONCLUSIONS Previously reported inconsistencies in the relationship between catechol-O-methyltransferase valine158 methionine genotypes and cognition were not resolved; however, catechol-O-methyltransferase genotype may affect expression of negative schizotypy by direct or indirect effects on central dopamine neurotransmitter signaling.