Range Of Cognitive Functions Research Articles

Acute glycaemic load breakfast manipulations do not attenuate cognitive impairments in adults with type 2 diabetes

Research on young healthy samples suggests that low glycaemic load foods can confer benefits for cognitive performance. The aim was to examine the effects of type 2 diabetes on cognitive function, and to investigate whether consumption of low glycaemic load breakfasts affects cognitive function in adults with type 2 diabetes. Memory, psychomotor skill and executive function were examined at two morning test sessions in 24 adults with type 2 diabetes and 10 adults with normal glucose tolerance (NGT) aged 45-77 years without dementia after water, low, and high glycaemic load breakfasts were consumed in accordance with a crossover, counterbalanced design. The type 2 diabetes and NGT groups were matched for education, depression, and IQ. Type 2 diabetes was associated with impairments in verbal memory, spatial memory, psychomotor skill, and executive function compared to adults with NGT. Consumption of the three breakfast conditions did not impact on cognitive performance in the type 2 diabetes or NGT participants. Abnormalities in glucose tolerance such as type 2 diabetes can have demonstrable negative effects on a range of cognitive functions. However, there was no evidence that low GL breakfasts administered acutely could confer benefits for cognitive function (ClincalTrials.gov identifier, NCT01047813).

The frontostriatal circuitry and behavioral complications in PD

Parkinson's disease (PD) is a progressive neurodegenerative disorder traditionally associated with motor symptoms. However, a number of reports have described also deficits across a range of cognitive functions and behavioral complications during the progression of the disease. Here, we summarize recent observations that may help us to understand the underlying neuronal correlates of behavioral complications in PD. We will report findings from cutting-edge imaging technology which in the last few years have provided the bulk of information on the neurobiological underpinnings of non-motor symptoms in PD.

The ADAS-cog in Alzheimer's disease clinical trials: psychometric evaluation of the sum and its parts

BackgroundThe Alzheimer's Disease Assessment Scale Cognitive Behavior Section (ADAS-cog), a measure of cognitive performance, has been used widely in Alzheimer's disease trials. Its key role in clinical trials should be...

Memory test tool.

Cognitive tests aid the diagnosis of dementia and are important in the medical and social management of patients. Many cognitive tests are available but none meets the three critical requirements for widespread use by a non-specialist: taking minimal operator time to administer, testing a reasonable range of cognitive functions and sensitivity to mild Alzheimer's disease. The TYM ('test your memory') is a series of ten tasks on a double- sided sheet of card with spaces for the patient to complete. The patient's ability to complete the test is the 11th task.

Neurocognitive profiles of people with comorbid depression and alcohol use: Implications for psychological interventions

Depression and alcohol use disorders frequently co-occur and are highly prevalent. Both conditions are known to impair cognitive functioning, yet research into the role of these impairments in response to Cognitive Behaviour Therapy (CBT) is limited. The purpose of the present study was to examine the relationship between baseline neuropsychological performance, severity of depressive symptoms and alcohol use disorders. Participants with current depression and hazardous alcohol use were functioning in the average range on all neuropsychological measures prior to treatment entry. Baseline measures of drinking severity and a range of cognitive functions were inversely correlated. After controlling for other baseline variables, superior baseline cognitive functioning predicted greater reductions in depression severity after 17 weeks. These predictive effects occurred across both brief and extended interventions. Findings suggest that improvement in depression following psychological treatment is enhanced by greater fluid reasoning ability and is predicted by executive functioning, regardless of the treatment length or problem focus.

White Matter Lesions and Cognitive Performance: The Role of Cognitively Complex Leisure Activity

Among persons with white matter lesions (WMLs), there is a range of cognitive function. We examine whether participation in leisure activities modifies the effect of WML load on cognitive function. Data are from 2300 men and women (aged 66-92 years) participating in the population-based Age Gene/Environment Susceptibility-Reykjavik Study. Subcortical WML load was calculated as a weighted sum, based on size of lesions in the four lobes. Periventricular WML load was calculated as the sum of lesion scores, based on size, for the frontal caps, occipitoparietal caps and bands. The upper quartile of lesion load in either area was compared to the lower three quartiles. Composite scores of memory (MEM), speed of processing (SP), and executive function (EF) were constructed from a battery of neuropsychological tests. Frequency of participation in nine cognitively stimulating leisure activities was assessed via questionnaire; the upper quartile was compared to the lower three quartiles. Multiple regression, controlling for demographic and health factors and brain infarcts, was used to test the main effects and interaction of WMLs and leisure activity on cognitive function. High leisure activity was associated with higher performance in all three cognitive abilities: MEM beta = 0.20, 95% confidence interval [CI], 0.11-0.29; SP beta = 0.37, 95% CI, 0.29-0.45; and EF beta = 0.23, 95% CI, 0.15-0.29. High WML load was associated with significantly lower performance in SP (beta = -0.06, 95% CI, -0.13 to -0.01). The effect of WMLs on SP performance was modified by high leisure activity (p for interaction <.05). Participation in cognitively stimulating leisure activity may attenuate the effect of WML pathology on cognitive performance.

Optimal TMS target site determination in cognitive studies: a systematic comparison of methods

In recent years the investigative domain of Transcranial Magnetic Stimulation (TMS) has expanded, now encompassing the whole range of cognitive functions and related brain areas. Consequently, the importance of how to determine the target stimulation site has increased and a number of alternative methods emerged. In this study we systematically compared four commonly used TMS coil positioning approaches by using them to induce behavioral change in a single cognitive study.

Schizophrenia: What do we know from functional magnetic resonance imaging?

Background and Aims:In this study, a summary of the main functional Magnetic Resonance Imaging (fMRI) findings in the field of schizophrenia will be given in order to get a better understanding of this disorder.Methods:The authors conducted an extensive literature review on fMRI and schizophrenia, using PubMed, the internet in general, and research contacts in order to avoid important literature to be left out.Results:In general, fMRI research on schizophrenia has demonstrated widespread deficits affecting a range of cognitive functions distributed throughout the brain. In addition, schizophrenia is associated with frontal and temporal brain dysfunction (e.g., Van den Noort & Bosch, 2008). This dysfunction is thought to be irreversible, or even worsen over time; even when optimal treatment is given (Lund et al., 2002). However, it is important to note that there is a degree of inconsistency in reported findings, and a pattern of brain dysfunction that would serve as a biological trait marker or predict treatment response has not emerged to date (e.g., Van den Noort & Bosch, 2008).Conclusions:In this study, it was found that patients with schizophrenia show widespread deficits affecting a range of cognitive functions distributed throughout the brain, but there is a degree of inconsistency in reported findings. Although the development of fMRI has provided the technological advance necessary to examine schizophrenia; the scientific challenge will be to incorporate this technique appropriately through prudent experimental design (e.g., Honey & Bullmore, 2002).

Synaptic proteins, neuropathology and cognitive status in the oldest-old

An increasing number of individuals in our population are surviving to over 90 years and a subset is at risk for developing dementia. However, senile plaque and neurofibrillary tangle pathology do not consistently differentiate individuals with and without dementia. Synaptic protein loss is a feature of aging and dementia and may dissociate 90+ individuals with and without dementia. Synaptophysin (SYN), postsynaptic density 95 (PSD-95) and growth-associated protein 43 (GAP-43) were studied in the frontal cortex of an autopsy series of 32 prospectively followed individuals (92–105 years) with a range of cognitive function. SYN protein levels were decreased in individuals with dementia and increased in those with clinical signs of cognitive impairment insufficient for a diagnosis of dementia. SYN but neither PSD-95 nor GAP-43 protein levels were significantly correlated with mini-mental status examination (MMSE) scores. Frontal cortex SYN protein levels may protect neuronal function in oldest-old individuals and reflect compensatory responses that may be involved with maintaining cognition.

Cerebellar involvement in executive control

The cerebellum has long been considered to be mainly involved in motor function. In the last 20 years, evidence from neuroimaging studies and from investigations of patients with cerebellar lesions has shown that the cerebellum plays a role in a range of cognitive functions. While cerebellar contributions have been shown for learning and memory, the cerebellum has also been linked to higher order cognitive control processes frequently referred to as executive functions. Although it is widely accepted that the cerebellum contributes to cognitive processing, the nature of cerebellar involvement is not well understood. The present paper focuses on the role of the cerebellum in executive processing, reviewing findings derived from neuroimaging studies or from studies investigating deficits related to cerebellar dysfunction. As executive functions cannot be considered as a unitary concept, special emphasis is put on cerebellar contributions to different aspects of executive control such as working memory, multitasking or inhibition. Referring to models derived from motor control, possible mechanisms of cerebellar involvement in executive processing are discussed. Finally, methodological problems in assessing executive deficits in general and in assessing the cerebellar contribution to executive processing in particular are addressed.

Neurocognitive function in current and ex-users of ecstasy in comparison to both matched polydrug-using controls and drug-naïve controls

Despite years of research and much controversy surrounding the effects of ecstasy use, findings are equivocal. Attempting to reduce methodological problems, such as concurrent use of other recreational drugs, could lead to a clearer picture of the effects of ecstasy use on cognitive function. The aim of this study is to investigate the effects of both prolonged abstention from ecstasy use and current use on cognitive function while controlling for the regular use of other recreational drugs used by ecstasy users (alcohol, cannabis, cocaine, amphetamines and lysergic acid diethylamide). A range of cognitive functions (including working memory, episodic memory, verbal learning and executive functions) was assessed in 109 participants: 25 current ecstasy users, 28 ex-ecstasy users (abstinent for at least 1 year), 29 polydrug-using controls (matched to both ecstasy-using groups for the use of other recreational drugs) and 27 drug-naïve controls. There was an overall tendency for impaired verbal learning and memory in both current ecstasy users and polydrug controls. There was also evidence of reduced response inhibition in the current ecstasy users and polydrug controls, which appeared to be related to recency of drug use. However, the majority of tests showed no group differences. The results suggest that recreational drug use in general, rather than ecstasy use per se, can lead to subtle cognitive impairments and that recent drug use appears to impact strongest on cognitive performance. This study highlights the importance of controlling for the use of all recreational drugs and, in particular, recent drug use when investigating 'effects of ecstasy' on cognitive function.

Effects of repeated doses of caffeine on performance and alertness: new data and secondary analyses

The effects of caffeine on mood and performance are well established. Some authors suggest that caffeine merely reverses effects of caffeine withdrawal rather than having direct behavioural effects. It has also been suggested that withdrawal may be removed by a first dose of caffeine and further doses have little subsequent effect. These issues are examined here. The present study aimed to determine whether caffeine withdrawal influenced mood and performance by comparing regular consumers who had been withdrawn from caffeine overnight with non-consumers. Following this repeated caffeine doses were administered to test the claim that repeated dosing has no extra effect on mood or performance. Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption. One hundred and twenty volunteers participated in the study. Regular caffeine consumption was assessed by questionnaire and this showed that 36 of the volunteers did not regularly consume caffeinated beverages. Volunteers were instructed to abstain from caffeine overnight and then completed a baseline session measuring mood and a range of cognitive functions at 08.00 the next day. Following this volunteers were given 0, or 1 mg/kg caffeine in a milkshake, glucose solution or water (at 09:00), followed by a second 0 or 1 mg/kg caffeine dose (at 09:40) and the test battery repeated at 10:00. The baseline data showed no effect of overnight caffeine withdrawal on mood or performance. In contrast, caffeine challenge improved vigilance performance and prevented decreases in alertness induced by completion of the task battery. The magnitude of these effects increased as a function of the number of doses of caffeine given. Secondary analyses of data from Christopher et al. (2003) also confirmed that effects of caffeine did not depend on length of withdrawal. The present findings show no effect of overnight caffeine withdrawal on mood and performance. Caffeine challenge did have the predicted effect on alertness and vigilance, with the size of the effects increasing with caffeine dose. These findings suggest that the effects of caffeine are not due to reversal of effects of withdrawal, a view confirmed by secondary analyses of data collected after a day of normal caffeine consumption.

Assessment of medication management by community-living elderly persons with two standardized assessment tools: A cross-sectional study

Background: The ability of patients to adhere to a medication regimen is imperative for achieving optimal outcomes. Elderly patients, especially those with memory loss, should be evaluated for their ability to manage medications to prevent significant drug-related problems. Assessment tools to determine the ability to manage medication therapy have not been tested in elderly patients with cognitive impairment. Objectives: This study compared the Medication Management Ability Assessment (M1V1AA) and the Drug Regimen Unassisted Grading Scale (DRUGS) as standardized tools to assess medication management skills in elderly patients with a range of cognitive function and evaluated the association between the results obtained from these scales and self-reported drug-related problems. Methods: This was a cross-sectional study of older individuals living in the community. At a scheduled study visit, the research assistant (RA) questioned participants with a structured interview to document demographic information, medical history, prescription use, over-the-counter drug and dietary supplement use, health care resource use, medication management practices, and adverse drug events. Cognitive status was assessed with the Mini-Mental State Examination (MMSE) and functional status with the instrumental activities of daily living rating scale. The MMAA, which uses a fictitious medication regimen with labeled prescription bottles, and the DRUGS, which uses the patient's own prescription bottles, were administered. Three months after the visit, the RA telephoned participants to determine recent changes in living situation and drug-related problems. Results: The study group comprised 52 people with a mean (SD) MMSE score of 28.3 (2.5). The participants had a mean (SD) age of 75.8 (6.2) years; 69% (36/52) were women, and 96% (50/52) were white. Participants reported an average of 4.1 medical conditions, and 88% (46/52) reported good to excellent health. Skipping doses or cutting them in half was reported by 25% (13/52) of participants who adjusted doses themselves. Almost half (44%) reported medication problems and/or medication ineffectiveness during the past 3 months at both the study visit and the 3-month follow-up (23/52 for both). The 49 participants who took the MMAA had a mean (SD) score of 19.4 (6.1), with a range of 0 to 25. Of the 49 participants with scores, 34 took less than the correct number of tablets and 13 took more. The 46 participants who took the DRUGS had a mean (SD) score of 91.6 (24.7), with a range of 0 to 100. Forty of 46 participants attempting the test attained the maximum score. Higher scores for both tests indicate better accuracy. Analysis revealed that the MMAA and the DRUGS correlated with one another ( P = 0.000). We found no significant associations between these medication management assessment tools and selfreported adherence or drug-related events. Conclusions: The MMAA and DRUGS tools correlated positively with cognitive function in this population of community-living elderly persons but need further evaluation of their ability to predict who is at greatest risk for drug related problems due to nonadherence to medication regimens.

Acute effects of caffeine in volunteers with different patterns of regular consumption

The effects of caffeine on mood and performance are well established. One explanation of these effects is that caffeine removes negative effects induced by prior caffeine withdrawal. This was tested here by comparing effects of caffeine in withdrawn consumers and non-consumers (who by definition were not withdrawn). The present study aimed to determine whether caffeine withdrawal influenced mood and performance by comparing regular consumers who had been withdrawn from caffeine overnight with non-consumers. Following this the effects of acute caffeine challenges were compared in withdrawn consumers and non-consumers. In addition, comparisons were made between those with higher and lower caffeine consumption. One hundred seventy-six volunteers participated in the study. Regular caffeine consumption was assessed by questionnaire and this showed that 56 of the sample did not regularly consume caffeinated beverages. Volunteers were instructed to abstain from caffeine overnight and then completed a baseline session measuring mood and a range of cognitive functions at 08.00 the next day. Following this approximately half of the volunteers were given 1 mg/kg caffeine in a milkshake or water (in the 'no caffeine' condition they were given just the milkshake or water) and the test battery repeated one hour later. A second test battery was carried out at 12.00 and a second caffeine challenge at 13.00. A final test session was carried out at 15.00. The baseline data revealed little evidence of effects of caffeine withdrawal on performance and mood. In contrast to this, caffeine produced a number of significant improvements in performance. There were some differences in the effects of caffeine on regular and non-consumers, with caffeine tending to reduce reaction time in regular consumers while the opposite was true for non-consumers. The present results show little evidence of effects of caffeine withdrawal on performance. In contrast, caffeine challenge produced improvements in aspects of performance and these were often not modified by regular caffeine consumption patterns. The differences in effects of caffeine that were observed between non-consumers and regular consumers were in functions that were unaffected by caffeine withdrawal. These findings show that the observed beneficial effects of caffeine cannot be interpreted in terms of a reversal of caffeine withdrawal.

Influence of differential housing on emotional behaviour and neurotrophin levels in mice

Environmental enrichment condition (EC) induces profound behavioural, neurochemical and neuroanatomical changes. Increasing evidence has shown that the hippocampus, which is implicated in a range of cognitive functions, including learning and memory, is one of the most susceptible brain areas to the effects of enriched rearing. Recent work also suggests that the hippocampus is functionally segregated; lesion studies have shown that the dorsal hippocampus is important for spatial learning, whereas the ventral part is critical in emotional behaviour in rats. We investigated the effects of differential housing environments on anxiety-related behaviour and neurotrophin levels in dorsal and ventral hippocampus, and other brain regions. Ninety-six male and female C57BL/6 mice were reared in EC or standard housing condition (SC) for 4 months after weaning. Thereafter sixty-four animals were tested in the elevated plus-maze, open-field, novel-objects exploration and food neophobia. Thirty-two animals remained as untested. Subsequently, brain nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were analysed in selected brain regions of the tested and non-tested animals. Differential housing influenced anxiety-related behaviour in the plus-maze and brain neurotrophins. Baseline levels of BDNF and NGF protein were differently distributed in dorsal and ventral parts of hippocampus in both male and female mice, with levels in the dorsal hippocampal being consistently higher than those in ventral hippocampus. Exposure to behavioural testing induced complex changes on neurotrophin levels in selected brain regions. This study demonstrates for the first time the differential distribution of normal levels of neurotrophin protein in dorsal and ventral hippocampus in mice, and these levels can be affected by environmental enrichment and have an impact on emotional behaviour.

Performance deficit of α7 nicotinic receptor knockout mice in a delayed matching‐to‐place task suggests a mild impairment of working/episodic‐like memory

Patients with schizophrenia exhibit deficits in a range of cognitive functions, particularly working and episodic memory, which are thought to be core features of the disorder. Memory dysfunction in schizophrenia is familial and thus a promising endophenotype for genetic studies. Both human and animal studies suggest a role for the neural nicotinic acid receptor family in cognition and specifically the alpha7-receptor subunit in schizophrenia and its endophenotypes. Consequently, we tested mice lacking the alpha7 subunit of the neural nicotinic receptor (B6.129S7-Chrna7(tm1Bay)/J) in the delayed matching-to-place (DMP) task of the Morris water maze, a measure of working/episodic memory akin to human episodic memory. We report that a minor impairment in alpha7 knockout mice was observed in the DMP task, with knockout mice taking longer to find the hidden platform than their wildtype controls. This suggests a role for the alpha7 subunit in working/episodic memory and a potential role for the alpha7 neural nicotinic receptor gene (CHRNA7) in schizophrenia and its endophenotypes.

EEG BIS-AD correlates with metrics of cognitive function in healthy subjects and in patients with Alzheimer’s disease

Background: EEG BIS® is a widely used monitor of the neurological effects of anesthesia that correlates with cognitive function metrics (e.g., MMSE, memory recall, and sedation level)[1-2]. BIS-AD, a novel revision (0.1) of BIS, was refined to correlate with dementia severity.Objective: To examine the association of BIS-AD and cognitive performance in healthy and demented elderly subjects. Methods: EEG and cognitive assessments (MMSE, ADAScog) were recorded from healthy elderly subjects (NML, CapeCod), patients recently diagnosed with mild AD (MildAD, McLean), and subjects with moderate to severe AD (ModAD, UCLA). Longitudinal assessments were recorded from healthy subjects (q3 mo., ongoing). BIS-AD was calculated from frontotemporal EEG during a three-minute vigilant, eyes-closed period. Partial correlation coefficients accounting for multiple subject visits measured association between BIS-AD and cognitive performance metrics. Results: 365 assessments (324 NML, 30 MildAD, 11 ModAD) were recorded from 111 subjects (84 NML, 16 MildAD, 11 ModAD) (age 79.9 /4.9). BIS-AD correlated with MMSE (R 0.290, p 0.001) and ADAScog (R -0.164, p 0.003), but not with age (i.e., BIS-AD was higher in subjects with better cognitive performance). Although the range of cognitive performance was small in the healthy subjects (MMSE: 28.8 /1.3; ADAScog: 7.4 /3.8), BIS-AD correlated with cognitive performance: MMSE (R 0.107, p 0.05) and ADAScog (R -0.136,p 0.018). At baseline, BIS-AD was higher in healthy subjects who performed better than the median score on both tests (i.e., MMSE 29 and ADAScog 8.1) than those who did not (96 vs. 94, p 0.039). At subsequent visits in healthy subjects, change in BIS-AD from baseline correlated with change in ADAScog (R -0.150 p 0.019) but not MMSE. Conclusions: BIS-AD correlated with cognitive performance in elderly healthy and demented subjects. BIS-AD was significantly higher at baseline in healthy subjects who performed in the upper 50% on both MMSE and ADAScog tests than those who did not. Change in BIS-AD over visits correlated with change in cognitive performance. Follow-up assessments in these subjects will reveal whether low BIS-AD values may be an early marker of dementia onset.

Serum lipids and hippocampal volume: The link to Alzheimer's disease?

The association between hippocampal volume (as a presumed index of Alzheimer's disease pathology) with serum total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol was studied in 86 elderly subjects with a range of cognitive functions. High-density lipoprotein cholesterol, but not low-density lipoprotein cholesterol or total cholesterol, was associated with hippocampal volume and dementia. This is compatible with protective effects of high-density lipoprotein cholesterol on hippocampal atrophy and Alzheimer's disease.

NEURAL SYNCHRONY AND GRAY MATTER VARIATION IN HUMAN MALES AND FEMALES: AN INTEGRATION OF 40 HZ GAMMA SYNCHRONY AND MRI MEASURES

Coherent cognition requires activity to be brought together across diverse brain networks. Synchronous, in-phase oscillations in the high-frequency (40 Hz) Gamma range are thought to be one mechanism underlying the functional integration of brain networks. While sex differences have been observed across a range of cognitive functions, their role in normal cortical synchronization has not been elucidated. We recorded Gamma phase synchrony in 500 male and 500 female subjects during an auditory oddball task, which taps discrimination of task-relevant signals. Results revealed a marked sex-linked dissociation in the spatio-temporal pattern of cortical synchronization. Females showed increased Gamma synchrony in the frontal brain, while males showed enhanced synchrony in the parieto-occipital region. These differences were not accounted for by sex differences in whole brain MRI volume. However, there were positive associations between Gamma synchrony and gray matter for females, while these relationships were negative for males. Sex differences in the profile of cortical synchronization may reflect distinct aspects of evolutionary advantage.

Serum lipids and hippocampal volume: The link to Alzheimer's disease?

The association between hippocampal volume (as a presumed index of Alzheimer's disease pathology) with serum total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol was studied in 86 elderly subjects with a range of cognitive functions. High-density lipoprotein cholesterol, but not low-density lipoprotein cholesterol or total cholesterol, was associated with hippocampal volume and dementia. This is compatible with protective effects of high-density lipoprotein cholesterol on hippocampal atrophy and Alzheimer's disease.