Brain aging in a sample of normal Egyptians cognition, education, addiction and smoking

The Role of Attentional Networks in Smoking Behavior Among Young Adults: Specific Contribution of Executive Control

INTRODUCTION

The exploration of cognitive impairments associated with tobacco use disorder has expanded during the last decades, centrally showing working memory and executive deficits among smokers. Despite their critical role in everyday life and in the smoking cessation process, attentional abilities have seldom been explored. Previous studies yielded discordant results, and the involvement of attentional deficits in smoking habits remains unclear.

AIMS AND METHODS

Capitalizing on the Attention Network Test, a theory-grounded task allowing the simultaneous but distinct evaluation of three attentional networks (alerting, orienting, executive control), we explored attentional abilities in three groups of 25 college students (nonsmokers, light smokers, heavy smokers), matched for demographic and psychopathological characteristics.

RESULTS

While light smokers did not present any deficit compared with nonsmokers, heavy smokers showed a specific impairment of the executive control subcomponent of attention, contrasting with preserved alerting and orienting attentional abilities. The executive control deficit was not related to current craving or to smoking duration.

CONCLUSIONS

Beyond the already explored memory and executive deficits, tobacco use disorder is associated with attentional impairments, characterized by a reduced ability to focus attentional resources on pertinent stimuli and resist to distractors interference. Given the assumed role of attentional impairments in smoking, our findings suggest that a critical step in future translational iterations is to develop neuropsychological rehabilitation programs tapping into the executive network of attention among smokers.

IMPLICATIONS

This study clarifies the presence and extent of attentional impairments in tobacco use disorder. We measured three attention networks (alerting, orienting, executive control) in light smokers, heavy smokers and matched healthy controls through a theory-grounded task (Attention Network Test). Heavy smokers (but not light ones) present a specific deficit for the executive control of attention. This deficit, uncorrelated with psychopathological comorbidities or current craving, appears directly related to smoking. Given the currently scattered literature on this topic, attentional processes deserve a thorough audit in tobacco use disorder, notably to develop specific neurocognitive rehabilitation.

Assessment of cognitive function in young children with type 1 diabetes mellitus using electrophysiological tests

BACKGROUND/OBJECTIVES

Diabetes mellitus is a chronic disease that affects many body systems, including the nervous and auditory systems. It is noted that there is a scarcity of research on the effect of diabetes on cognitive functions in particular and auditory functions in general in children with type 1 diabetes. Therefore, this study was designed to assess cognitive and auditory functions in children with type 1 diabetes mellitus and to correlate the reflection of diabetes control on cognitive functions.

METHODS

This study is a case-control study that included 100 children divided into two groups, the patient group, which includes 50 children with type 1 diabetes, and the control group, which consists of 50 healthy children. Subjects in the current study were submitted to pure tone audiometry, speech recognition threshold test, immittancemetry study, and measurement of cortical auditory evoked and P300 potentials (CAEPs and P300). These audiometric measures were statistically analyzed and correlated with the clinical characteristics of the study group.

RESULTS

The latency of P300 and CAEPs was significantly increased while the amplitude of P300 and CAEPs was significantly decreased in the patient group compared to the control group (p < 0.001). P300 and CAEPs latency has a positive correlation with HbA1c levels (r = 0.460). In addition, there was significant differences between the two groups regarding the hearing threshold at 8000 Hz, and 28% of patients had bilateral sensorineural hearing loss (SNHL) at 8 kHz.

CONCLUSION

The prolonged P300 and CAEPs latency and decreased amplitude in patients indicate a cognitive decline in individuals with type 1 diabetes compared to healthy individuals. HbA1c levels may increase the risk of cognitive impairment in children. In addition, the risk of bilateral SNHL increased at 8 kHz in children with type 1 diabetes mellitus.

Reliability of a cognitive endpoint for use in a multiple sclerosis pharmaceutical trial

OBJECTIVE

Determine reliability and basic psychometric properties of a composite cognitive endpoint, MS-COG, for monitoring change in cognitive function in MS drug trials.

BACKGROUND

50% of MS patients have cognitive impairment that impacts ability to work and quality of life. We selected neuropsychological tests based on sensitivity to MS cognitive impairment, availability of alternate forms, cross-cultural utility, and feasibility for multicenter trials, and assessed the reliability and validity of a composite endpoint, MS-COG.

DESIGN/METHODS

Administered SRT, BVMT-R, PASAT, and SDMT to 60 MS patients at 4 US centers twice over 45days, along with symptom inventories by patients and informants.

RESULTS

The MS-COG had test-retest reliability of 0.91. Processing Speed and Memory indices had reliabilities of 0.89 and 0.86, with modest practice effects. Reliability was high for the RR MS and SP MS subgroups as well, with correlations of .90 and .93, respectively for MS-COG. Overall, 42% of subjects obtained MS-COG scores in the impaired range, with SP MS subjects performing 0.8 SD below RR MS subjects. Impairment correlated well (r=0.37 to 0.40) with informant reports but was inconsistent with patient report, with the least reliable assessments by those with greater symptom severity.

CONCLUSIONS

The MS-COG is a reliable, repeatable measure of MS cognitive functioning that is sensitive to cognitive impairment in SP MS and RR MS patients and feasible for multicenter clinical trials. Further development is warranted.

Δ⁹Tetrahydrocannabinol impairs visuo-spatial associative learning and spatial working memory in rhesus macaques

Cannabis remains the most commonly abused illicit drug and is rapidly expanding in quasi-licit use in some jurisdictions under medical marijuana laws. Effects of the psychoactive constituent Δ⁹tetrahydrocannabinol (Δ⁹THC) on cognitive function remain of pressing concern. Prior studies in monkeys have not shown consistent evidence of memory-specific effects of Δ⁹THC on recognition tasks, and it remains unclear to what extent Δ⁹THC causes sedative versus specific cognitive effects. In this study, adult male rhesus monkeys were trained on tasks which assess spatial working memory, visuo-spatial associative memory and learning as well as motivation for food reward. Subjects were subsequently challenged with 0.1-0.3 mg/kg Δ⁹THC, i.m., in randomized order and evaluated on the behavioral measures. The performance of both vsPAL and SOSS tasks was impaired by Δ⁹THC in a dose and task-difficulty dependent manner. It is concluded that Δ⁹THC disrupts cognition in a way that is consistent with a direct effect on memory. There was evidence for interference with spatial working memory, visuo-spatial associative memory and incremental learning in the latter task. These results and the lack of specific effect of Δ⁹THC in prior visual recognition studies imply a sensitivity of spatial memory processing and/or working memory to endocannabinoid perturbation.

Chronic cigarette smoking: implications for neurocognition and brain neurobiology

Compared to the substantial volume of research on the general health consequences associated with chronic smoking, little research has been specifically devoted to the investigation of its effects on human neurobiology and neurocognition. This review summarizes the peer-reviewed literature on the neurocognitive and neurobiological implications of chronic cigarette smoking in cohorts that were not seeking treatment for substance use or psychiatric disorders. Studies that specifically assessed the neurocognitive or neurobiological (with emphasis on computed tomography and magnetic resonance-based neuroimaging studies) consequences of chronic smoking are highlighted. Chronic cigarette smoking appears to be associated with deficiencies in executive functions, cognitive flexibility, general intellectual abilities, learning and/or memory processing speed, and working memory. Chronic smoking is related to global brain atrophy and to structural and biochemical abnormalities in anterior frontal regions, subcortical nuclei and commissural white matter. Chronic smoking may also be associated with an increased risk for various forms of neurodegenerative diseases. The existing literature is limited by inconsistent accounting for potentially confounding biomedical and psychiatric conditions, focus on cross-sectional studies with middle aged and older adults and the absence of studies concurrently assessing neurocognitive, neurobiological and genetic factors in the same cohort. Consequently, the mechanisms promoting the neurocognitive and neurobiological abnormalities reported in chronic smokers are unclear. Longitudinal studies are needed to determine if the smoking-related neurobiological and neurocognitive abnormalities increase over time and/or show recovery with sustained smoking cessation.

Prescription use disorders in older adults

The number of older adults needing substance abuse treatment is projected to rise significantly in the next few decades. This paper will focus on the epidemic of prescription use disorders in older adults. Particular vulnerabilities of older adults to addiction will be considered. Specifically, the prevalence and patterns of use of opioids, stimulants, and benzodiazepines will be explored, including the effects of these substances on morbidity and mortality. Treatment intervention strategies will be briefly discussed, and areas for future research are suggested.

Cognitive function and event-related potentials in children with type 1 diabetes mellitus

Type 1 diabetes mellitus is associated with cognitive changes, but the extent of cognition decline depends on age at onset, duration of diabetes, and occurrence of attacks of hypoglycemia or ketoacidosis. This study was designed to assess cognitive function in a group of children with type 1 diabetes mellitus. A total of 40 diabetic children were recruited from the pediatric department of Assiut University Hospital, Egypt. Forty healthy children matched for age, sex, and socioeconomic status were chosen as controls for comparison. Cognition was assessed using Stanford-Binet and event-related potentials tests. Compared to the control group, patients reported a significant reduction in intelligent quotient, comprehension, abstract visual reasoning, quantitative reasoning, bead memory, and total short memory testing for cognitive functions. Prolonged N1, P200, N2, and P300 latencies and reduced P300-N2 amplitude were reported. Significant negative correlations were identified in most studied cognitive functions and ketoacidosis or family history of diabetes mellitus.

Subchronic toxicity of cannabis leaves on male albino rats

Cannabis is the most commonly abused drug in the world. In Egypt, the Anti Narcotic General Administration showed that the narcotics problem costs the Egyptian economy approximately 800 million dollars annually. LD(50), lethal dose that kills 50% of the treated animals, of the bango was determined and then selected groups of rats were given tenth of LD(50) for 90 days. The histopathological effects were determined. All the studied organs were affected markedly in the form of shrunken cells in brain. The liver cells were affected in the form of rarefaction of the cytoplasm, kidneys were with severe congestion. The testicles were with disruption of the spermatogenic cells from the membrane.

Risk factors for bango abuse in upper Egypt

Cannabis is the most commonly abused drug in the world. In Egypt, the Anti Narcotic General Administration, showed that the narcotics problem costs the Egyptian economy approximately 800 million dollars annually. The present study was designed to determine the risk factors that lead to bango abuse among secondary school students and drivers in Assiut province. Urine samples were taken from 1000 volunteers after filling questionnaires and the risk factors were determined. Ethical consideration and informed consent was taken on. In drivers, the study found that bango abuse was concentrated in age group (21 to <31 years) and in those driving microbus, van and half van. In students, abuse concentrated in male students by 100%, and in those with high daily fund. The abused students tend to be more aggressive. Also, tend to be lazy to share in school activities. Abused students present in large family (8-11 persons) and families with troubles between parents (81% in divorced parents). In conclusion, bango abuse leads to deterioration of the academic achievement, and may be associated with antisocial and violent behavior.

Drugs of abuse and the aging brain

Substance abuse among older adults has received little attention in the past, presumably because this population has traditionally accounted for only a small percentage of the drug abuse problem in the United States. The aging of the baby boomer generation (born 1946-1964), however, will soon swell the ranks of older adults and dramatically alter the demography of American society. Several observations suggest that this expansion will likely be accompanied by a precipitous increase in the abuse of drugs, including prescription medications and illicit substances, among older adults. While it is now evident that the brain changes continuously across life, how drugs of abuse interact with these age-related changes remains unclear. The dynamic nature of brain function, however, suggests that substance abuse during older age may augment the risks and require unique considerations for diagnosis and treatment. In addition to describing current and projected prevalence estimates of substance abuse among older adults, the present review discusses how aging affects brain systems involved in drug abuse, and explores the potential impact of drug abuse on the aging brain. Future directions for substance abuse research among older adults will also be considered.

Cannabinoid function in learning, memory and plasticity

Marijuana and its psychoactive constituents induce a multitude of effects on brain function. These include deficits in memory formation, but care needs to be exercised since many human studies are flawed by multiple drug abuse, small sample sizes, sample selection and sensitivity of psychological tests for subtle differences. The most robust finding with respect to memory is a deficit in working and short-term memory. This requires intact hippocampus and prefrontal cortex, two brain regions richly expressing CB1 receptors. Animal studies, which enable a more controlled drug regime and more constant behavioural testing, have confirmed human results and suggest, with respect to hippocampus, that exogenous cannabinoid treatment selectively affects encoding processes. This may be different in other brain areas, for instance the amygdala, where a predominant involvement in memory consolidation and forgetting has been firmly established. While cannabinoid receptor agonists impair memory formation, antagonists reverse these deficits or act as memory enhancers. These results are in good agreement with data obtained from electrophysiological recordings, which reveal reduction in neural plasticity following cannabinoid treatment, and increased plasticity following antagonist exposure. The mixed receptor properties of the pharmacological tool, however, make it difficult to define the exact role of any CB1 receptor population in memory processes with any certainty. This makes it all the more important that behavioural studies use selective administration of drugs to specific brain areas, rather than global administration to whole animals. The emerging role of the endogenous cannabinoid system in the hippocampus may be to facilitate the induction of long-term potentiation/the encoding of information. Administration of exogenous selective CB1 agonists may therefore disrupt hippocampus-dependent learning and memory by 'increasing the noise', rather than 'decreasing the signal' at potentiated inputs.

Chronic cannabis abuse raises nerve growth factor serum concentrations in drug-naive schizophrenic patients

Long-term cannabis abuse may increase the risk of schizophrenia. Nerve growth factor (NGF) is a pleiotropic neurotrophic protein that is implicated in development, protection and regeneration of NFG-sensitive neurones. We tested the hypothesis that damage to neuronal cells in schizophrenia is precipitated by the consumption of cannabis and other neurotoxic substances, resulting in raised NGF serum concentrations and a younger age for disease onset. The NGF serum levels of 109 consecutive drug-naive schizophrenic patients were measured and compared with those of healthy controls. The results were correlated with the long-term intake of cannabis and other illegal drugs. Mean (+/- SD) NGF serum levels of 61 control persons (33.1 +/- 31.0 pg/ml) and 76 schizophrenics who did not consume illegal drugs (26.3 +/- 19.5 pg/ml) did not differ significantly. Schizophrenic patients with regular cannabis intake (> 0.5 g on average per day for at least 2 years) had significantly raised NGF serum levels of 412.9 +/- 288.4 pg/ml (n = 21) compared to controls and schizophrenic patients not consuming cannabis (p < 0.001). In schizophrenic patients who abused not only cannabis, but also additional substances, NGF concentrations were as high as 2336.2 +/- 1711.4 pg/ml (n = 12). On average, heavy cannabis consumers suffered their first episode of schizophrenia 3.5 years (n = 21) earlier than schizophrenic patients who abstained from cannabis. These results indicate that cannabis is a possible risk factor for the development of schizophrenia. This might be reflected in the raised NGF-serum concentrations when both schizophrenia and long-term cannabis abuse prevail.

Brain aging in normal Egyptians: cognition, education, personality, genetic and immunological study

Studying the cognitive and immunological changes that occur in old age as well as genetic function have been considered an important subject to differentiate between normal brain aging and early dementia especially Alzheimer's disease. The aim of this study is to stress on age-related neuropsychological and electrophysiological (P(300)) changes in normal Egyptian subjects, to throw light on the value of genetic (Apo-E(4) genotype) and immunological markers [interleukin-6 (IL-6) and intercellular adhesion molecules (ICAM-1) in the serum] as tools used in early detection of cognitive decline in cerebral aging. Ninety-four normal Egyptian subjects (below and above 60 years) were submitted to the following: (1) neuropsychological tests for testing memory, perception, psychomotor performance and attention, (2) Eysenck Personality Questionnaire (EPQ) for personality traits, (3) event-related potential study (P(300), latency and amplitude), (4) genetic test for detection of Apolipoprotein E genotype and (5) immunological studies including detection of the level of IL-6 and ICAM-1 in serum. There was a significant impairment of memory, psychomotor performance and perception in elderly subjects particularly males and subjects with low level of education. Regarding personality, significantly high scores were obtained in neuroticism scale of EPQ in elderly subjects. Apo-E(3)/E(3) was the most common genotype encountered in Egyptian subjects (49.1%). It was found that subjects with Apo-E(4) genotype did significantly worse in scores of intentional memory test (sensory memory) when compared with other genotypes. Statistically significant impairment in attention and sensory memory was found in subjects with high IL-6 level. This could not be detected in subjects with high ICAM-1 level. In conclusion, advancing age and lower levels of education are considered risk factors for cognitive decline in normal brain aging. Neuropsychological tests remain as the highly sensitive tools for detection of early cognitive impairment. Neurotic traits are more encountered in old age. Apo-E(4) genotype is associated with significant sensory (intentional) memory impairment. High IL-6 level in the serum is accompanied by significant impairment in attention and sensory (intentional) memory.

Nonacute (residual) neuropsychological effects of cannabis use: a qualitative analysis and systematic review

Because there is a possibility that cannabis or cannabis-like molecules might be used as treatments for certain conditions in the future, it becomes important to consider the possible adverse effects of these compounds. In this paper, the authors review the evidence for persisting effects of nonacute cannabis use on the central nervous system, as reflected by alteration in neuropsychological performance. From the 40 articles that met criteria for inclusion in this review, the authors could not detect consistent evidence for persisting neuropsychological deficits in cannabis users; however, 22 of the 40 studies reported at least some subtle impairments. The inability to reach a firm conclusion results largely from methodological limitations inherent in most studies. These are considered in detail to inform future studies on (nonacute) consequences of cannabis consumption on cognitive abilities.

Prevalence of Alzheimer's type dementia in an elderly Arab population

The aim of this study was to estimate the prevalence of dementia of the Alzheimer type (DAT) in an Arab Israeli community. Epidemiological studies of dementia have rarely been reported in Arab populations. The target population, aged 60 years or older, comprised 821 persons (362 males) who, on 1 October 1995, were residents of the rural area of Wadi Ara. These persons were examined for symptoms of dementia (DSM-IV criteria), using a semistructured questionnaire for collection of demographic and medical data. Age, gender, and education-specific prevalence rates were calculated for this population and compared to those obtained in other studies. DAT was diagnosed in 20.5% of this population. Its prevalence increased steeply with age, from 8% among those younger than 70 years to 33% among those aged 70-79 and 51% among those 80 years or older. Illiteracy was very common in this population, and strongly associated with higher prevalence of DAT (27% vs. 4%, P < 0.001). DAT was more prevalent among females than males (25% vs. 15%, P < 0.001). However, illiteracy was also significantly more frequent among women (96% vs. 42%, P < 0.001). After correction for illiteracy, the gender difference lost statistical significance. Few women smoked, but among men, the prevalence of DAT in those who smoked was lower as compared to non-smokers (14% vs. 23%, a non-significant difference). These results were confirmed by logistic regression wherein DAT was included as the dependent variable and age, illiteracy, gender and smoking as independent variables (OR=2.8, 2.8, 1.2 and 0.7, respectively; P < 0.005 for each, except for smoking). Our findings suggest that this population is unique because of extremely high rates of dementia. While the results support a protective effect of schooling against the development of dementia, other factors (e.g. genetic) must be sought to explain this high frequency.