Neurocognitive outcomes in children with chronic kidney disease: Current findings and contemporary endeavors

Given the rise in chronic kidney disease (CKD) in both children and adults, CKD has recently been targeted as a public health priority. Childhood onset kidney disease is generally a noncurable and progressive condition that leads to kidney failure by early adulthood. Fortunately, improved identification of kidney problems allows for early intervention, which is thought to slow progression toward end-stage renal disease. In addition, medical interventions for pediatric end-stage renal disease have also improved, allowing children to take advantage of lifesaving renal replacement treatments such as dialysis and kidney transplantation. In spite of improvements in identification and treatment, CKD causes both direct and indirect insults to a variety of organ systems. This paper reviews recently published studies pertaining to the neurocognitive and psychosocial impact of CKD on children of various ages and at various stages of kidney failure. Specific attention is focused on summarizing peer reviewed research that describes associations between kidney functioning and cognitive functioning, language acquisition, visual spatial abilities, memory, and executive functioning. In addition, peer reviewed research describing psychosocial outcomes associated with CKD related to academic achievement, social-behavioral functioning, and quality of life are summarized. The authors also identified disease-specific factors that likely mediate neurocognitive outcomes (e.g., anemia, hypertension, cardiovascular) and endorse the importance of continued interdisciplinary research collaborations that will provide a better understanding of the mechanisms responsible for improved neurocognitive functioning after transplantation. The authors conclude this review by describing a multicenter, prospective, longitudinal, National Institutes of Health funded study that is currently examining the developmental outcomes of children with mild to moderate CKD. The authors speculate that the Chronic Kidney Disease in Children Prospective Cohort Study (CKiD) findings will provide additional evidence-based guidance for clinicians and researchers working with children and adolescents with deteriorating kidney function to improve medical and developmental outcomes.     

Adult Chronic Kidney Disease: Neurocognition in Chronic Renal Failure

In recent years there has been a keen interest in the neurocognitive sequelae of renal failure and subsequent end-stage renal disease given its increasing prevalence and incidence. This review article summarizes the relevant information on cognitive functioning in chronic kidney disease in adults before the initiation of dialysis, after the initiation of dialysis, and after renal transplantation. In general, compared to pre-dialysis, there is an improvement in cognitive function after the institution of dialysis and further improvement after renal transplantation. Throughout the paper an attempt is made to highlight the importance of considering disease related variables in the neuropsychological assessment of individuals with chronic kidney disease. The paper concludes with a discussion of future avenues of research.     

Apolipoprotein E and cognitive performance: a meta-analysis

The epsilon4 allele of the apolipoprotein E (APOE) gene is a known risk factor for Alzheimer's disease and may also affect cognitive performance in normal aging. Evidence of the presence and magnitude of epsilon4-related cognitive deficits was examined with a meta-analysis of the available literature. Thirty-eight studies were included, and cognitive performance was collapsed into 8 domains. Results indicated significant APOE-epsilon4 group differences for global cognitive functioning, episodic memory, and executive functioning, in favor of non-epsilon4 carriers. In addition, older age and APOE-epsilon4 heterozygosity was associated with smaller epsilon4-related impairments. The meta-analysis results suggest that APOE-epsilon4 genotype does affect cognitive performance in healthy aging, although the influence is relatively small and specific to certain domains of cognitive performance.     

Working memory in healthy aging and in Parkinson’s disease: evidence of interference effects

Focusing on relevant information while suppressing the irrelevant one are critical abilities for different cognitive processes. However, their functioning has been scarcely investigated in the working memory (WM) domain, in both healthy and pathological conditions. The present research aimed to study these abilities in aging and Parkinson’s disease (PD), testing three groups of healthy participants (young, older and elderly) and one of PD patients, employing a new experimental paradigm. Results showed that the transient storing of irrelevant information in WM causes substantial interference effects, which were remarkable in elderly individuals on both response latency and accuracy. Interestingly, PD patients responded faster and were equally accurate compared to a matched control group. Taken together, findings confirm the existence of similar mechanisms for orienting attention inwards to WM contents or outwards to perceptual stimuli, and suggest the suitability of our task to assess WM functioning in both healthy aging and PD.     

Type 2 Diabetes Mellitus and Cognitive Performance in a Population-Based Sample of the Oldest Old: Impact of Comorbid Dementia

We examined the relationship between type 2 diabetes mellitus and cognitive function in a population-based sample of very old people. The sample comprised 338 persons, aged 80-93 years (mean age 83.5 years), of whom 70 persons had type 2 diabetes mellitus. Measures of cognitive functioning included tests of perceptual speed, visuo-spatial ability, inductive reasoning, short-term memory, semantic memory, episodic memory, and the Mini-Mental State Examination. Regression analyses showed that type 2 diabetes mellitus duration was related to test performance across all cognitive domains, with the exception of short-term memory, such that longer duration was associated with lower test performance. When cases with dementia were excluded from the sample, further analyses showed that diabetes duration was not associated with cognitive test performance. This indicates that diabetes is not related to lower cognitive function in the general population of non-demented old people. Diabetes, however, increases the risk for cerebrovascular incidents, like stroke, that may contribute to vascular dementia.     

Cognitive Performance and the Role of Control Beliefs in Midlife

Midlife has been touted as being a time of peak performance in many different areas of functioning. In the present study, we investigated whether this was true for cognitive functioning on tasks assessing speed, reasoning, short-term memory, and vocabulary. We also explored the extent to which levels of cognitive functioning could be attributed to individual differences in general control beliefs. Middle-aged adults showed little or no cognitive declines on speed, reasoning, and short-term memory measures relative to the young and outperformed the young on vocabulary. Relative to the elderly, middle-aged adults scored higher on all tasks except vocabulary, for which there were no differences. Adults in midlife, on the other hand, had lower scores on measures of general control beliefs compared to younger adults. Thus, although midlife is a time of high cognitive functioning, it is also a time of lower beliefs about control. To investigate the relationship between control beliefs and cognitive performance, we used structural equation modeling. The models showed that for adults in midlife, control beliefs were predictive of performance but only for the reasoning task after background variables were considered. Specifically, high levels of control beliefs were associated with better cognitive performance. More work is needed to identify mediational processes linking control beliefs and cognitive performance for various age groups and to determine whether some cognitive processes are more controllable than others.     

Memantine facilitates memory consolidation and reconsolidation in the day-old chick

Memantine is a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist that has been approved for the treatment of the cognitive deficits noted in Alzheimer's disease. While there is a body of research that supports memantine's facilitative action upon memory compromise, this series of studies aimed to investigate the effects of this drug in healthy animals with intact memory functioning. A 0.1 mM dose of memantine injected immediately after a weakly aversive training event (i.e. 20% v/v methyl anthranilate) was found to enhance passive avoidance learning for this event in day-old chicks up to 24 h following training. The same dose of memantine was also observed to enhance memory for the training event when it was administered in conjunction with a reminder trial. These results suggest that memantine is capable of facilitating both memory consolidation as well as memory reconsolidation. It was concluded that memantine's mechanism may involve the short-term or intermediate memory phases of the Gibbs and Ng model of memory, and that the current findings represent enhancement of intact memory, rather than amelioration of memory compromise.     

The Effects of Estrogen Replacement Therapy on Neuropsychological Functioning in Postmenopausal Women With and Without Dementia: A Critical and Theoretical Review

We review 42 studies examining the effects of estrogen replacement therapy (ERT) on memory and cognition in nondemented postmenopausal women. Although there are an appreciable number of nonsignificant findings, the number of significant findings favoring ERT users considerably outnumbers the rare findings of better performance in controls. Experimental studies demonstrate a consistent beneficial effect on verbal memory, but these are short-term studies of the more acute effects of ERT. The observational studies suggest that there may be a long-lasting effect of continued ERT on cognitive functioning, but these studies need to be interpreted with caution because of the lack of random assignment and a possible healthy user bias. We also summarize findings from studies on the effects of ERT on Alzheimer's disease (AD). ERT is associated with a decreased risk for dementia, but there is little evidence for a positive effect on cognition in women with AD. Definitive answers to questions about the long-term effects of ERT on cognitive aging and risk of developing AD should be provided by 3 ongoing clinical trials.     

Cognitive function and young drivers: The relationship between driving,attitudes, personality and cognition

Young drivers (aged 17–25 years) are the highest risk age group for driving crashes and are over-represented in car crash statistics in Australia. A relationship between cognitive functioning and driving in older drivers (60 years and older) has been consistently supported in previous literature, however, this relationship has been neglected in research regarding younger drivers. The role of cognitive functioning in young people’s driving was investigated both independently and within a current model of younger peoples driving performance. With young drivers as participants, driving behaviour, attitudes, personality and cognitive functioning were tested and driving performance was operationalised through two measures on a driving simulator, speeding and lane deviations. Cognitive functioning was found to contribute to driving behaviour, along with driving attitudes and personality traits, in accounting for young people’s driving performance. The young drivers who performed better on cognitive functioning tasks engaged in less speeding behaviour and less lane deviation on the driving simulator than those who performed worse on these tasks. This result was found independent of the role of driving behaviour, driving attitudes and personality traits, accounting for unique variance in driving ability.     

Psychometric assessment of cardiac transplantation candidates

Psychometric assessment protocols were used to chart the course of 287 end-stage cardiac patients' psychological adjustment at pretransplantation and, again, in 34 who were subsequently transplanted. The regression and repeated-measures analyses suggested that psychological distress is typical of the adult transplantation candidate, although impaired cognitive functioning is more typical of the acute postoperative stage. Negative affect, cognitive, personality, and coping measures are interrelated at pretransplantation; depression and mental control show significant decreases at 2 weeks posttransplantation. Whereas the transplantation process is inherently distressing, psychological testing may identify cognitive and personality features that require more specific clinical attention.     

The effects of cognitive demand upon relationships between working memory and cognitive skills

The present study explored the effects of cognitive demand upon relationships between working memory and cognitive skills. Both children and adults were tested on a measure of short-term memory and three measures of counting span, which varied in cognitive demand. When statistically controlling for short-term memory and the speed of counting operations, the more demanding the counting-span task, the closer its relationship with cognitive skills. The results are discussed in terms of practical and theoretical implications for working memory research.     

The effects of cognitive demand upon relationships between working memory and cognitive skills

The present study explored the effects of cognitive demand upon relationships between working memory and cognitive skills. Both children and adults were tested on a measure of short-term memory and three measures of counting span, which varied in cognitive demand. When statistically controlling for short-term memory and the speed of counting operations, the more demanding the counting-span task, the closer its relationship with cognitive skills. The results are discussed in terms of practical and theoretical implications for working memory research.     

Cognitive function of youths born to mothers with opioid and poly-substance abuse problems during pregnancy

Previous research has provided inconclusive evidence regarding the neuropsychological difficulties of children born to mothers partaking in opioid or poly-drug use during pregnancy. Little is known about how these children fare as they get older. The present longitudinal study includes follow-up data on 45 children born to mothers who used heroin and poly-drugs and a group of 48 children without prenatal drug exposure. Most of the drug-exposed youths were placed in permanent foster or adoptive homes before one year of age. The youths (ages 17 to 21) were administered 10 neuropsychological tests. The drug-exposed youths had cognitive and fine motor functions within the normal range compared to population norms but performed significantly worse than the non-exposed group. There were indications of generally lower cognitive functions rather than specific problems with executive functioning. Lower mean birthweight in the risk group (619 grams mean difference, p < .001) only partially mediated the group differences in cognitive functioning. There was a tendency for youths who had few and early changes in their caregivers or who were born to mothers who had used the least number of different drugs during pregnancy to have the best cognitive scores. The study indicates that youths born to mothers who used multiple drugs during pregnancy are vulnerable relative to their peers within a wide range of cognitive functions. The vulnerability seems to be related not only to the mother’s drug use during pregnancy but also to factors such as birthweight and unstable parental care during infancy.     

Relationship of cognitive strategy use to prospective memory performance in a diverse sample of nondemented older adults with varying degrees of cognitive complaints and impairment

Although older adults typically have better performance on prospective memory (PM) tasks carried out in naturalistic settings, a paucity of research directly assesses older adults’ use of compensatory strategies on such tasks. The current study investigates external memory strategy use during performance of a clinical PM test that features both short-term (in laboratory) and long-term (out of laboratory) subtasks (i.e., the Royal Prince Alfred Prospective Memory Test – RPA-ProMem. Nondemented, community-dwelling older adults (n = 214; mean age = 80.5; 68.2% female; 39.7% non-white) with mild cognitive impairment, subjective cognitive decline, and healthy controls completed the RPA-ProMem while external strategy use was permitted and recorded. Overall, participants utilized external strategies 41% of the time on the RPA-ProMem. Increased utilization of external memory strategies was significantly associated with better PM performance. Additionally, better performance on executive functioning tasks was associated with increased use of external memory strategies. Results are discussed in relation to how memory strategy use can be enhanced to improve everyday memory ability in older adults at risk for dementia.     

Cognitive plasticity in Alzheimer's disease patients receiving cognitive stimulation programs

The main purpose of this article is to examine whether cognitive plasticity increases after cognitive training in Alzheimer's disease patients. Twenty six patients participated in this study, all of them diagnosed with mild Alzheimer's disease, 17 of them received a cognitive training program during 6 months, and the other 9 were assigned to the control group. Participants were assigned to experimental or control conditions for clinical reasons. In order to assess cognitive plasticity, all patients were assessed before and after treatment with three subtests from the "Bateria de Evaluación de Potencial de Aprendizaje en Demencias" [Assessment Battery of Learning Potential in Dementia] (BEPAD). After treatment, Alzheimer's disease patients improved their performance in all the tasks assessing cognitive plasticity: viso-spatial memory, audio-verbal memory and verbal fluency. However, the cognitive plasticity scores of the patients in the control group decreased. In conclusion, this study showed that cognitive stimulation programs can improve cognitive functioning in mildly demented patients, and patients who do not receive any cognitive interventions may reduce their cognitive functioning.     

Cognitive dysfunction in depression: neurocircuitry and new therapeutic strategies

Major depressive disorder (MDD) is a disabling medical condition associated with significant morbidity, mortality and public health costs. However, neurocircuitry abnormalities underlying depression remain incompletely understood and consequently current treatment options are unfortunately limited in efficacy. Recent research has begun to focus specifically on cognitive aspects of depression and potential neurobiological correlates. Two fundamental types of cognitive dysfunction observed in MDD are cognitive biases, which include distorted information processing or attentional allocation toward negative stimuli, and cognitive deficits, which include impairments in attention, short-term memory and executive functioning. In this article, we present a selective review of current research findings in these domains and examine neuroimaging research that is beginning to characterize the neurocircuitry underlying these biases and deficits. We propose that deficient cognitive functioning, attention biases and the sustained negative affect characteristic of MDD can be understood as arising in part from dysfunctional prefrontal-subcortical circuitry and related disturbances in the cognitive control of emotion. Finally, we highlight potential new pharmacological and non-pharmacological therapeutic strategies for MDD based on an evolving mechanistic understanding of the disorder.     

Can fluid intelligence be reduced to ‘simple’ short-term storage?

Much is written regarding the associations between human intelligence and cognition. However, it is unusual to find comprehensive studies. Here twenty four measures tapping eight cognitive abilities and skills are considered for assessing a sample of one hundred and eighty five young adults. The simultaneous relationships among fluid, crystallized, and spatial intelligence, along with short-term memory, working memory capacity, executive updating, attention, and processing speed are analyzed using a latent-variable approach. The key findings show that (a) short-term storage, working memory, and updating are hardly distinguishable, and (b) fluid intelligence is near-perfectly correlated with these three cognitive functions. It is concluded that this nuclear intelligence component can be largely identified with basic and general short-term storage processes, namely, encoding, maintenance, and retrieval.     

Semantic encoding deficits in a case of traumatic amnesia

A 33-year-old patient was studied neuropsychologically 19 years after sustaining severe head trauma. A recent CT scan showed lesions in the left frontal and right temporal regions. Performance on standard memory tests, both verbal and visuospatial, was extremely poor, although other intellectual functioning was relatively spared. The patient showed some interesting deficits in semantic processing. In a depth of processing task there was no advantage for words where semantic encoding had been induced. Neither was there any release from proactive interference after shifts in semantic categories. Deficits were also observed in short-term memory distractor tasks as well as in cueing tasks. These findings suggest that the cognitive deficits commonly observed in Korsakoff's disease can also be present in other amnesic disorders and may in part be related to cortical and especially frontal lobe atrophy.     

Individual differences in anxiety and executive functioning: A multidimensional view

The relationship between individual differences in anxiety and executive functioning was investigated in a sample of young adults. Verbal and spatial working memory, resistance to interference, negative priming, and task‐switching measures were used to assess three executive functioning dimensions: updating, inhibition, and shifting. An additional index of basic psychomotor speed was added to this cognitive battery. According to the multidimensional interaction model of anxiety proposed by Endler (1997), state (cognitive–worry and autonomic–emotional) and trait (related to social evaluation, physical danger, ambiguous situations, and daily routines) anxiety were assessed in this evaluation context. Results indicated that shifting and inhibition (negative priming) efficiency were negatively related to state (cognitive–worry) and trait (related to social evaluation) anxiety. However, there was a relative advantage of subjects higher in social evaluation apprehensions in their memory updating performance. The results are consistent with several predictions of the attentional control theory (Eysenck, Derakshan, Santos, & Calvo, 2007), and are relevant for research regarding the interaction of situational, personality, and cognitive functioning dimensions.     

短时记忆的一生发展研究

短时记忆的发展一直是认知发展领域的一个重要课题。近年来一生发展的思想给短时记忆的发展研究又注入了新的内容。文章介绍了关于从婴儿到老年各个时期中短时记忆发展状况及其机制的研究进展。对短时记忆在一生发展中是否存在真正的容量变化、个体差异原因与发展变化原因的关系、短时记忆的一生发展过程等基本问题进行了讨论。