Memory Performance In Adults Research Articles

Self-concept clarity and autobiographical memory functions in adults with Autism Spectrum Disorders without Intellectual Deficiency

Background Various aspects of self-disorders have been reported in Autism Spectrum Disorder (ASD). If the contents of self have been studied (i.e. knowledge or beliefs about the self such as personality traits or values), much less is known about structural characteristics of the self-concept in this population. The latter refers to how self-knowledge components are organized and can be experienced by individuals in the form of a clarity of self-concept. It is intimately related to the activity of remembering one's past, that is to autobiographical memory. Therefore, we aimed at exploring self-concept clarity and its association to autistic symptoms and autobiographical memory functions in adults with ASD. Method The self-concept clarity and autobiographical memory (AM) functions of 42 well-documented adults with ASD without ID (27 men) were compared to 42 controls participants using Bayesian analyses. Results Our results showed both a lower clarity of self-concept and a lower social function of autobiographical memory in the ASD group compared to controls. The clarity of self-concept was also negatively correlated with the self-function of autobiographical memory in both groups, but contrary to our predictions, no relevant correlation was observed between clarity of self-concept and autistic symptoms in the ASD group. Limitations Both self-concept clarity and autobiographical memory functions were assessed using self-administered questionnaires. IQ of ASD individuals was higher than that of controls despite matching on education level. Conclusion Our study points a lower self-concept clarity together with a lower social function of autobiographical memory in adults with ASD without ID. It provides new evidence for an alteration of structural aspects of the self that goes beyond those of previous studies that were more restricted to self-knowledge. However, further researches are needed to better understand the link between self-disorders in ASD, autistic symptoms and other aspects of autobiographical memory.

Association of Estradiol and Visceral Fat With Structural Brain Networks and Memory Performance in Adults

Changes in estradiol during aging are associated with increased dementia risk. It remains unclear how estradiol supports cognitive health and whether risk factors, such as midlife obesity, are exacerbated by estrogen loss. To assess whether visceral adipose tissue (VAT) moderates the association between age and brain network structure and to investigate whether estradiol moderates the association between VAT and brain network structure. Cross-sectional study of data from 974 cognitively healthy adults in Germany who participated in the Health Study of the Leipzig Research Centre for Civilization Diseases, a previously described population-based cohort study. Two moderation analyses were performed, including VAT as the moderator variable between age and brain network structure and estradiol as the moderator variable between VAT and brain network structure. The study was conducted from August 1, 2011, to November 23, 2014. Analyses were conducted from August 2017 to September 2018. Serum estradiol levels from fasting blood and visceral adipose tissue volume from T1-weighted magnetic resonance imaging (MRI). Brain network covariance (individual loading on structural network derived from T1-weighted MRI) and memory performance (composite score from the Consortium to Establish a Registry for Alzheimer Disease [CERAD] verbal episodic memory test on learning [score range, 0-30], recall [score range, 0-10], and recognition [score range, 0-20]). Final analyses included data from 473 women (mean [SD] age, 50.10 [15.63] years) and 501 men (mean [SD] age, 51.24 [15.67] years). Visceral adipose tissue was associated with an exacerbation of the negative association of aging with network covariance for women (interaction term β = -0.02; 95% bias-corrected bootstrap CI, -0.03 to -0.01; P = .001) and men (interaction term β = -0.02; 95% bias-corrected bootstrap CI, -0.03 to -0.01; P < .001). Estradiol level was associated with a reduction in the negative association of VAT with network covariance in women (interaction term β = 0.63; 95% bias-corrected bootstrap CI, 0.14-1.12; P = .01), with no significant association in men. In the female midlife subgroup (age range, 35-55 years, when menopause transition occurs), low estradiol levels were associated with lower memory network covariance (Cohen d = 0.61; t80 = 2.76; P = .007) and worse memory performance (Cohen d = 0.63; t76 = 2.76; P = .007). This study reports a novel association between VAT, estradiol, and structural brain networks as a potential mechanism underlying cognitive decline in women. These findings appear to highlight the need for sex-specific strategies, including VAT and hormonal screening during midlife, to support healthy cognitive aging.

The Mediterranean Diet and 2-Year Change in Cognitive Function by Status of Type 2 Diabetes and Glycemic Control.

OBJECTIVETo determine associations of a Mediterranean diet score (MeDS) with 2-year change in cognitive function by type 2 diabetes and glycemic control status and contrast it against other diet quality scores.RESEARCH DESIGN AND METHODSWe used data from the longitudinal Boston Puerto Rican Health Study (n = 913; 42.6% with type 2 diabetes at 2 years). Glycemic control at baseline was categorized as uncontrolled (hemoglobin A1c ≥7% [53 mmol/mol]) versus controlled. Two-year change in glycemic control was defined as stable/improved versus poor/declined. We defined MeDS, Healthy Eating Index, Alternate Healthy Eating Index, and Dietary Approaches to Stop Hypertension scores. Adjusted mixed linear models assessed 2-year change in global cognitive function z score, executive and memory function, and nine individual cognitive tests.RESULTSHigher MeDS, but no other diet quality score, was associated with higher 2-year change in global cognitive function in adults with type 2 diabetes (β ± SE = 0.027 ± 0.011; P = 0.016) but not in those without (P = 0.80). Similar results were noted for Mini-Mental State Examination, word recognition, digit span, and clock drawing tests. Results remained consistent for individuals under glycemic control at baseline (0.062 ± 0.020; P = 0.004) and stable/improved over 2 years (0.053 ± 0.019; P = 0.007), but not for individuals with uncontrolled or poor/declined glycemic control. All diet quality scores were associated with higher 2-year memory function in adults without type 2 diabetes.CONCLUSIONSBoth adhering to a Mediterranean diet and effectively managing type 2 diabetes may support optimal cognitive function. Healthy diets, in general, can help improve memory function among adults without type 2 diabetes.

Progesterone receptor expression in cajal-retzius cells of the developing rat dentate gyrus: Potential role in hippocampus-dependent memory.

The development of medial temporal lobe circuits is critical for subsequent learning and memory functions later in life. The present study reports the expression of progesterone receptor (PR), a powerful transcription factor of the nuclear steroid receptor superfamily, in Cajal-Retzius cells of the molecular layer of the dentate gyrus of rats. PR was transiently expressed from the day of birth through postnatal day 21, but was absent thereafter. Although PR immunoreactive (PR-ir) cells did not clearly express typical markers of mature neurons, they possessed an ultrastructural morphology consistent with neurons. PRir cells did not express markers for GABAergic neurons, neuronal precursor cells, nor radial glia. However, virtually all PR cells co-expressed the calcium binding protein, calretinin, and the glycoprotein, reelin, both reliable markers for Cajal-Retzius neurons, a transient population of developmentally critical pioneer neurons that guide synaptogenesis of perforant path afferents and histogenesis of the dentate gyrus. Indeed, inhibition of PR activity during the first two weeks of life impaired adult performance on both the novel object recognition and object placement memory tasks, two behavioral tasks hypothesized to describe facets of episodic-like memory in rodents. These findings suggest that PR plays an unexplored and important role in the development of hippocampal circuitry and adult memory function.

Interview styles, adult’s recall and personality in investigative interview settings: Mediation and moderation effects

Previous studies have investigated the effects of a humanitarian rapport-orientated and a dominant non-rapport-orientated interview style on the memory performance of adults in two interviews separ...

Comparison of visual and verbal memory performance of adults aged 50 and above: 3K3S, Logical memory test

Weschler Memory Test (WMS) is one of the most important tests to distinguish normal aging from cognitive impairment. Logical Memory Test is the subtest in the WMS. The Three Words and Three Shapes (3W3S) test is a frequently used memory and learning test in our country. 3W3S has both visual and verbal modalities and it is also short and easy to use. This test allows us to easily distinguish normal aging from other dementias. In this study, normative data were collected for both tests. The aim of the study is to identify normative values of our country using the two subtests with new addition of recognition and cue recall subtests to the Logical Memory subtest. In this study we have 389 participants and their ages are 50 years and above. According to the results, it was found that both the 3W3S and the Logical memory Test performances were predicted by age, gender and education variables. Apparently, the scores of the 3W3S subtests for both shapes and words sections and Logical Memory Tests decrease when age increase and education level decrease.

Consequences of Adolescent Exposure to the Cannabinoid Receptor Agonist WIN55,212-2 on Working Memory in Female Rats.

Marijuana is a prevalent illicit substance used by adolescents, and several studies have indicated that adolescent use can lead to long-term cognitive deficits including problems with attention and memory. However, preclinical animal studies that observe cognitive deficits after cannabinoid exposure during adolescence utilize experimenter administration of doses of cannabinoids that may exceed what an organism would choose to take, suggesting that contingency and dose are critical factors that need to be addressed in translational models of consequences of cannabinoid exposure. Indeed, we recently developed an adolescent cannabinoid self-administration paradigm in male rats, and found that prior adolescent self-administration of the cannabinoid receptor agonist WIN55,212-2 (WIN) resulted in improved working memory performance in adulthood. In addition, the doses self-administered were not as high as those that are found to produce memory deficits. However, given known sex differences in both drug self-administration and learning and memory processes, it is possible that cannabinoid self-administration could have different cognitive consequences in females. Therefore, we aimed to explore the effects of self-administered vs. experimenter-administered WIN in adolescent female rats on adult cognitive function. Female rats were trained to self-administer WIN daily throughout adolescence (postnatal day 34–59). A control group self-administered vehicle solution. The acute effects of adolescent WIN self-administration on memory were determined using a short-term spatial memory test 24 h after final SA session; and the long-term effects on cognitive performance were assessed during protracted abstinence in adulthood using a delayed-match-to-sample working memory task. In a separate experiment, females were given daily intraperitoneal (IP) injections of a low or high dose of WIN, corresponding to self-administered and typical experimenter-administered doses, respectively, or its vehicle during adolescence and working memory was assessed under drug-free conditions in adulthood. While self-administration of WIN in adolescence had no significant effects on short-term spatial memory or adult working memory, experimenter administration of WIN resulted in improved adult working memory performance that was more pronounced in the low dose group. Thus, low-dose adolescent WIN exposure, whether self-administered or experimenter-administered, results in either improvements or no change in adult working memory performance in female rats, similar to previous results found in males.

Resting sympathetic arousal moderates the association between parasympathetic reactivity and working memory performance in adults reporting high levels of life stress.

The neurovisceral integration model stipulates that autonomic function plays a critical role in the regulation of higher-order cognitive processes, yet most work to date has examined parasympathetic function in isolation from sympathetic function. Furthermore, the majority of work has been conducted on normative samples, which typically demonstrate parasympathetic withdrawal to increase arousal needed to complete cognitive tasks. Little is known about how autonomic regulation supports cognitive function in populations exposed to high levels of stress, which is critical given that chronic stress exposure alters autonomic function. To address this, we sought to characterize how parasympathetic (high-frequency heart rate variability, HF-HRV) and sympathetic (preejection period, PEP) measures of cardiac function contribute to individual differences in working memory (WM) capacity in a sample of high-risk women. HF-HRV and PEP were measured at rest and during a visual change detection measure of WM. Multilevel modeling was used to examine within-person fluctuations in WM performance throughout the task concurrently with HF-HRV and PEP, as well as between-person differences as a function of resting HF-HRV and PEP levels. Results indicate that resting PEP moderated the association between HF-HRV reactivity and WM capacity. Increases in WM capacity across the task were associated with increases in parasympathetic activity, but only among individuals with longer resting PEP (lower sympathetic arousal). Follow-up analyses showed that shorter resting PEP was associated with greater cumulative risk exposure. These results support the autonomic space framework, in that the relationship between behavior and parasympathetic function appears dependent on resting sympathetic activation.

Childhood poverty is associated with altered hippocampal function and visuospatial memory in adulthood

Childhood poverty is a risk factor for poorer cognitive performance during childhood and adulthood. While evidence linking childhood poverty and memory deficits in adulthood has been accumulating, underlying neural mechanisms are unknown. To investigate neurobiological links between childhood poverty and adult memory performance, we used functional magnetic resonance imaging (fMRI) during a visuospatial memory task in healthy young adults with varying income levels during childhood. Participants were assessed at age 9 and followed through young adulthood to assess income and related factors. During adulthood, participants completed a visuospatial memory task while undergoing MRI scanning. Patterns of neural activation, as well as memory recognition for items, were assessed to examine links between brain function and memory performance as it relates to childhood income. Our findings revealed associations between item recognition, childhood income level, and hippocampal activation. Specifically, the association between hippocampal activation and recognition accuracy varied as a function of childhood poverty, with positive associations at higher income levels, and negative associations at lower income levels. These prospective findings confirm previous retrospective results detailing deleterious effects of childhood poverty on adult memory performance. In addition, for the first time, we identify novel neurophysiological correlates of these deficits localized to hippocampus activation.

Development of the Word Auditory Recognition and Recall Measure: A Working Memory Test for Use in Rehabilitative Audiology.

The purpose of this study was to develop the Word Auditory Recognition and Recall Measure (WARRM) and to conduct the inaugural evaluation of the performance of younger adults with normal hearing, older adults with normal to near-normal hearing, and older adults with pure-tone hearing loss on the WARRM. The WARRM is a new test designed for concurrently assessing word recognition and auditory working memory performance in adults who may have pure-tone hearing loss. The test consists of 100 monosyllabic words based on widely used speech-recognition test materials. The 100 words are presented in recall set sizes of 2, 3, 4, 5, and 6 items, with 5 trials in each set size. The WARRM yields a word-recognition score and a recall score. The WARRM was administered to all participants in three listener groups under two processing conditions in a mixed model (between-subjects, repeated measures) design. The between-subjects factor was group, with 48 younger listeners with normal audiometric thresholds (younger listeners with normal hearing [YNH]), 48 older listeners with normal thresholds through 3000 Hz (older listeners with normal hearing [ONH]), and 48 older listeners with sensorineural hearing loss (older listeners with hearing loss [OHL]). The within-subjects factor was WARRM processing condition (no additional task or with an alphabet judgment task). The associations between results on the WARRM test and results on a battery of other auditory and memory measures were examined. Word-recognition performance on the WARRM was not affected by processing condition or set size and was near ceiling for the YNH and ONH listeners (99 and 98%, respectively) with both groups performing significantly better than the OHL listeners (83%). The recall results were significantly better for the YNH, ONH, and OHL groups with no processing (93, 84, and 75%, respectively) than with the alphabet processing (86, 77, and 70%). In both processing conditions, recall was best for YNH, followed by ONH, and worst for OHL listeners. WARRM recall scores were significantly correlated with other memory measures. In addition, WARRM recall scores were correlated with results on the Words-In-Noise (WIN) test for the OHL listeners in the no processing condition and for ONH listeners in the alphabet processing condition. Differences in the WIN and recall scores of these groups are consistent with the interpretation that the OHL listeners found listening to be sufficiently demanding to affect recall even in the no processing condition, whereas the ONH group listeners did not find it so demanding until the additional alphabet processing task was added. These findings demonstrate the feasibility of incorporating an auditory memory test into a word-recognition test to obtain measures of both word recognition and working memory simultaneously. The correlation of WARRM recall with scores from other memory measures is evidence of construct validity. The observation of correlations between the WIN thresholds with each of the older groups and recall scores in certain processing conditions suggests that recall depends on listeners' word-recognition abilities in noise in combination with the processing demands of the task. The recall score provides additional information beyond the pure-tone audiogram and word-recognition scores that may help rehabilitative audiologists assess the listening abilities of patients with hearing loss.

Sex-specific effects of prenatal chronic mild stress on adult spatial learning capacity and regional glutamate receptor expression profiles

Both animal experiments and clinical studies have demonstrated that prenatal stress can cause cognitive disorders in offspring. To explore the scope of these deficits and identify potential underlying mechanisms, we examined the spatial learning and memory performance and glutamate receptor (GluR) expression patterns of adult rats exposed to prenatal chronic mild stress (PCMS). Principal component analysis (PCA) was employed to reveal the interrelationships among spatial learning indices and GluR expression changes. Female PCMS-exposed offspring exhibited markedly impaired spatial learning and memory in the Morris water maze (MWM) task compared to control females, while PCMS-exposed males showed better initial spatial learning in the MWM compared to control males. PCMS also altered basal and post-MWM glutamate receptor expression patterns, but these effects differed markedly between sexes. Male PCMS-exposed offspring exhibited elevated basal expression of NR1, mGluR5, and mGluR2/3 in the prefrontal cortex (PFC), whereas females showed no basal expression changes. Following MWM training, PCMS-exposed males expressed higher NR1 in the PFC and mammillary body (MB), higher mGluR2/3 in PFC, and lower NR2B in the hippocampus (HIP), PFC, and MB compared to unstressed MWM-trained males. Female PCMS-exposed offspring showed strongly reduced NR1 in MB and NR2B in the HIP, PFC, and MB, and increased mGluR2/3 in PFC compared to unstressed MWM-trained females. This is the first report suggesting that NMDA subunits in the MB are involved in spatial learning. Additionally, PCA further suggests that the NR1–NR2B form is the most important for spatial memory formation. These results reveal long-term sex-specific effects of PCMS on spatial learning and memory performance in adulthood and implicate GluR expression changes within HIP, PFC, and MB as possible molecular mechanisms underlying cognitive dysfunction in offspring exposed to prenatal stress.

Concord grape juice, cognitive function, and driving performance: a 12-wk, placebo-controlled, randomized crossover trial in mothers of preteen children

AbstractBackground: Daily consumption of Concord grape juice (CGJ) over 3–4 mo has been shown to improve memory function in adults with mild cognitive impairment and reduce blood pressure in hypertensive adults. These benefits likely result from the high concentration of polyphenols in CGJ. Increased stress can impair cognitive function and elevate blood pressure. Thus, we examined the potential beneficial effect of CGJ in individuals with somewhat stressful and demanding lifestyles.Objective: We sought to examine the effects of the daily consumption of CGJ for 12 wk on cognitive function, driving performance, and blood pressure in healthy, middle-aged working mothers.Design: Twenty-five healthy mothers (aged 40–50 y) of preteen children who were employed for ≥30 h/wk consumed 12 ounces (355 mL) of either CGJ (containing 777 mg total polyphenols) or an energy-, taste-, and appearance-matched placebo daily for 12 wk according to a randomized crossover design with a 4-wk washout. Verbal and spatial memory, executive function, attention, blood pressure, and mood were assessed at baseline and at 6 and 12 wk. Immediately after the cognitive battery, a subsample of 17 women completed a driving performance assessment at the University of Leeds Driving Simulator. The 25-min driving task required participants to match the speed and direction of a lead vehicle.Results: Significant improvements in immediate spatial memory and driving performance were observed after CGJ relative to placebo. There was evidence of an enduring effect of CGJ such that participants who received CGJ in arm 1 maintained better performance in the placebo arm.Conclusions: Cognitive benefits associated with the long-term consumption of flavonoid-rich grape juice are not exclusive to adults with mild cognitive impairment. Moreover, these cognitive benefits are apparent in complex everyday tasks such as driving. Effects may persist beyond the cessation of flavonoid consumption, and future studies should carefully consider the length of washout within crossover designs. This trial was registered at clinicaltrials.gov as NCT01411631.

Does developmental timing of exposure to child maltreatment predict memory performance in adulthood? Results from a large, population-based sample

Although maltreatment is a known risk factor for multiple adverse outcomes across the lifespan, its effects on cognitive development, especially memory, are poorly understood. Using data from a large, nationally representative sample of young adults (Add Health), we examined the effects of physical and sexual abuse on working and short-term memory in adulthood. We examined the association between exposure to maltreatment as well as its timing of first onset after adjusting for covariates. Of our sample, 16.50% of respondents were exposed to physical abuse and 4.36% to sexual abuse by age 17. An analysis comparing unexposed respondents to those exposed to physical or sexual abuse did not yield any significant differences in adult memory performance. However, two developmental time periods emerged as important for shaping memory following exposure to sexual abuse, but in opposite ways. Relative to non-exposed respondents, those exposed to sexual abuse during early childhood (ages 3–5), had better number recall and those first exposed during adolescence (ages 14–17) had worse number recall. However, other variables, including socioeconomic status, played a larger role (than maltreatment) on working and short-term memory. We conclude that a simple examination of “exposed” versus “unexposed” respondents may obscure potentially important within-group differences that are revealed by examining the effects of age at onset to maltreatment.

Prospective and episodic memory in relation to hippocampal volume in adults with spina bifida myelomeningocele.

The present study examined prospective and episodic memory in relation to age, functional independence, and hippocampal volume in younger to middle-aged adults with spina bifida myelomeningocele (SBM) and typically developing (TD) adults. Prospective and episodic memory, as well as hippocampal volume, was reduced in adults with SBM relative to TD adults. Neither memory performance nor hippocampal volume showed greater decrements in older adults. Lower hippocampal volume was associated with reduced prospective memory in adults with SBM, and this relation was specific to the hippocampus and not to a contrast structure, the amygdala. Prospective memory mediated the relation between hippocampal volume and functional independence in adults with SBM. The results add to emerging evidence for reduced memory function in adults with SBM and provide quantitative evidence for compromised hippocampal macrostructure as a neural correlate of reduced memory in this population.

Fruits, vegetables, 100% juices, and cognitive function.

Although reviews of the association between polyphenol intake and cognition exist, research examining the cognitive effects of fruit, vegetable, and juice consumption across epidemiological and intervention studies has not been previously examined. For the present review, critical inclusion criteria were human participants, a measure of fruit, vegetable, or 100% juice consumption, an objective measure of cognitive function, and a clinical diagnosis of neuropsychological disease. Studies were excluded if consumption of fruits, vegetables, or juice was not assessed in isolation from other food groups, or if there was no statistical control for education or IQ. Seventeen of 19 epidemiological studies and 3 of 6 intervention studies reported significant benefits of fruit, vegetable, or juice consumption for cognitive performance. The data suggest that chronic consumption of fruits, vegetables, and juices is beneficial for cognition in healthy older adults. The limited data from acute interventions indicate that consumption of fruit juices can have immediate benefits for memory function in adults with mild cognitive impairment; however, as of yet, acute benefits have not been observed in healthy adults. Conclusions regarding an optimum dietary intake for fruits, vegetables, and juices are difficult to quantify because of substantial heterogeneity in the categorization of consumption of these foods.

An examination of the consequences of chronic exposure to Mitragyna speciosa during adolescence on learning and memory in adulthood

Although an emerging drug of concern in the United States and Europe, the active alkaloids associated the Mitragyna speciosa plant have long been utilized for a number of purposes ranging from use as an antitussive to that of anti-inflammatory or analgesic purposes. Known by a number of common names, in the United States it is normally legally sold as Kratom. However, little is known about the consequences of the main constituent, mitragynine or any of the more than two dozen identified plant alkaloids on neuropsychological development, learning and memory, and behavior. In the present experiment, adolescent rats were given repeated injections of saline, 15 mg/kg, or 50 mg/kg of Mitragyna speciosa extract. Once the animals reached 107 days of age, they were assessed for general activity, retention on a step-down passive avoidance task, trained using tasks with spatial components of various levels of difficulty, a spatial learning set task, and a plus maze response learning task. In some but not all of the Morris water maze tasks, escape latencies for the 50 mg/kg but not 15 mg/kg rats were significantly longer than that of saline control animals. Nonetheless, performance across groups on probe trials was comparable. In addition, during learning set testing the escape times for the three groups were comparable and, more important, they were able to respond on trial two on the basis of what they learned on the first trial by the end of training. For plus maze response learning testing, all three groups made a comparable number of reference memory errors. Conversely, the 50 mg/kg drug group made significantly more total and working memory errors than the saline-treated animals. The results suggest that chronic exposure to the alkaloids present in legally available Kratom during adolescence is capable of producing a variety of subtle but lasting changes affecting spatial and working memory performance in adulthood, well after the exposure to Kratom has ended.

Task importance affects event-based prospective memory performance in adults with HIV-associated neurocognitive disorders and HIV-infected young adults with problematic substance use.

Two experiments were conducted to examine the effects of task importance on event-based prospective memory (PM) in separate samples of adults with HIV-associated neurocognitive disorders (HAND) and HIV-infected young adults with substance use disorders (SUD). All participants completed three conditions of an ongoing lexical decision task: (1) without PM task requirements; (2) with PM task requirements that emphasized the importance of the ongoing task; and (3) with PM task requirements that emphasized the importance of the PM task. In both experiments, all HIV+ groups showed the expected increase in response costs to the ongoing task when the PM task's importance was emphasized. In Experiment 1, individuals with HAND showed significantly lower PM accuracy as compared to HIV+ subjects without HAND when the importance of the ongoing task was emphasized, but improved significantly and no longer differed from HIV+ subjects without HAND when the PM task was emphasized. A similar pattern of findings emerged in Experiment 2, whereby HIV+ young adults with SUD (especially cannabis) showed significant improvements in PM accuracy when the PM task was emphasized. Findings suggest that both HAND and SUD may increase the amount of cognitive attentional resources that need to be allocated to support PM performance in persons living with HIV infection.

A Neuropsychological Assessment of the Effects of Chronic Ketamine Exposure in a Rodent Model of Drug Abuse

While used as paediatric and veterinary anaesthetic and for pain management, the nonselective NMDA (N-methyl-D- aspartate) antagonist ketamine also remains popular among recreational users. As such, there is legitimate concern about the psychological and physiological consequences associated with chronic abuse of this drug. The purpose of the present investigation was to assess the impact of chronic exposure to ketamine following a period of abstinence in a rodent model of ketamine abuse. In the present experiment, rats were given repeated injections of saline, 5 mg/kg, or 40 mg/kg of ketamine. Beginning at 111 days of age, the animals were tested for retention of an aversive outcome on a step-down avoidance task and assessed for general levels of activity. In addition, the animals were trained on a series of tasks with spatial components of various levels of difficulty, a spatial learning set task, and a nonspatial response learning task. On early trials with water maze tasks of varying difficulty, the ketamine-treated rats were impaired relative to controls, with dose-dependent effects observed on many of the tasks. On probe trials the drug-treated animals spent significantly less time in the target quadrant. In addition, the performance of the drug-treated rats was inferior to that of the control animals on a spatial learning set task, and a response learning task suggesting some difficulty in adapting their responses to changing task demands. The results suggest that chronic exposure to this NMDA receptor antagonist in young adult rats is capable of producing a variety of changes that affect nonspatial learning and memory performance in adulthood, well after the drug exposure period.

Adolescent social defeat decreases spatial working memory performance in adulthood

BackgroundAdolescent social stress is associated with increased incidence of mental illnesses in adulthood that are characterized by deficits in cognitive focus and flexibility. Such enhanced vulnerability may be due to psychosocial stress-induced disruption of the developing mesocortical dopamine system, which plays a fundamental role in facilitating complex cognitive processes such as spatial working memory. Adolescent rats exposed to repeated social defeat as a model of social stress develop dopaminergic hypofunction in the medial prefrontal cortex as adults. To evaluate a direct link between adolescent social stress and later deficits in cognitive function, the present study tested the effects of adolescent social defeat on two separate tests of spatial working memory performance.MethodsAdult rats exposed to adolescent social defeat and their controls were trained on either the delayed win-shift task or the delayed alternating T-Maze task and then challenged with various delay periods. To evaluate potential differences in motivation for the food reward used in memory tasks, consumption and conditioned place preference for sweetened condensed milk were tested in a separate cohort of previously defeated rats and controls.ResultsCompared to controls, adult rats defeated in adolescence showed a delay-dependent deficit in spatial working memory performance, committing more errors at a 90 s and 5 min delay period on the T-maze and win-shift tasks, respectively. Observed memory deficits were likely independent of differences in reward motivation, as conditioned place preference for the palatable food used on both tasks was similar between the adolescent social defeat group and control.ConclusionsThe results demonstrate that severe social stressors during adolescence can produce long term deficits in aspects of cognitive function. Given the dependence of spatial working memory on prefrontal dopamine, pharmacologically reversing dopaminergic deficiencies caused by adolescent social stress has the potential to treat such cognitive deficits.

The efficacy of cognitive prosthetic technology for people with memory impairments: A systematic review and meta-analysis

Technology can compensate for memory impairment. The efficacy of assistive technology for people with memory difficulties and the methodology of selected studies are assessed. A systematic search was performed and all studies that investigated the impact of technology on memory performance for adults with impaired memory resulting from acquired brain injury (ABI) or a degenerative disease were included. Two 10-point scales were used to compare each study to an ideally reported single case experimental design (SCED) study (SCED scale; Tate et al., 2008) or randomised control group study (PEDro-P scale; Maher, Sherrington, Herbert, Moseley, & Elkins, 2003). Thirty-two SCED (mean = 5.9 on the SCED scale) and 11 group studies (mean = 4.45 on the PEDro-P scale) were found. Baseline and intervention performance for each participant in the SCED studies was re-calculated using non-overlap of all pairs (Parker & Vannest, 2009) giving a mean score of 0.85 on a 0 to 1 scale (17 studies, n = 36). A meta-analysis of the efficacy of technology vs. control in seven group studies gave a large effect size (d = 1.27) (n = 147). It was concluded that prosthetic technology can improve performance on everyday tasks requiring memory. There is a specific need for investigations of technology for people with degenerative diseases.