Neuropsychology

Testing covariates of Type 2 diabetes-cognition associations in older adults: Moderating or mediating effects?
Objective: The general goal of this study was to advance our understanding of Type 2 diabetes (T2D)-cognition relationships in older adults by linking and testing comprehensive sets of potential moderators, potential mediators, and multiple cognitive outcomes. Method: We identified in the literature 13 health-related (but T2D-distal) potential covariates, representing four informal domains (i.e., biological vitality, personal affect, subjective health, lifestyle activities). Cross-sectional data from the Victoria Longitudinal Study (age range = 53–90 years; n = 41 T2D and n = 458 control participants) were used. We first examined whether any of the 13 potential covariates influenced T2D-cognition associations, as measured by a comprehensive neuropsychological battery (15 measures). Next, using standard regression-based moderator and mediator analyses, we systematically tested whether the identified covariates would significantly alter observed T2D-cognition relationships. Results: Six potential covariates were found to be sensitive to T2D associations with performance on seven cognitive measures. Three factors (systolic blood pressure, gait-balance composite, subjective health) were significant mediators. Each mediated multiple cognitive outcomes, especially measures of neurocognitive speed, executive functioning, and episodic memory. Conclusions: Our findings offer a relatively comprehensive perspective of T2D-related cognitive deficits, comorbidities, and modulating influences. The implications for future research reach across several fields of study and application. These include (1) neuropsychological research on neural and biological bases of T2D-related cognitive decline, (2) clinical research on intervention and treatment strategies, and (3) larger-scale longitudinal studies examining the potential multilateral and dynamic relationships among T2D status, related comorbidities, and cognitive outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Influence of age on practice effects in longitudinal neurocognitive change.
Objective: Longitudinal comparisons of neurocognitive functioning often reveal stability or age-related increases in performance among adults under about 60 years of age. Because nearly monotonic declines with increasing age are typically evident in cross-sectional comparisons, there is a discrepancy in the inferred age trends based on the two types of comparisons. The current research investigated the role of practice effects in longitudinal comparisons on the discrepancy. Method: Longitudinal data over an average interval of 2.5 years were available on five abilities (i.e., reasoning, spatial visualization, episodic memory, perceptual speed, vocabulary) in a sample of 1,616 adults ranging from 18 to over 80 years of age. Practice effects were estimated from comparisons of the performance of people of the same age tested for either the first or second time, after adjusting for the possibility of selective attrition. Results: Increased age was associated with significantly more negative longitudinal changes with each ability. All of the estimated practice effects were positive, but they varied in magnitude across neurocognitive abilities and as a function of age. After adjusting for practice effects the longitudinal changes were less positive at younger ages and slightly less negative at older ages. Conclusions: It was concluded that some, but not all, of the discrepancy between cross-sectional and longitudinal age trends in neurocognitive functioning is attributable to practice effects positively biasing the longitudinal trends. These results suggest that the neurobiological substrates of neurocognitive functioning may change across different periods in adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Relationship between depression, fatigue, subjective cognitive impairment, and objective neuropsychological functioning in patients with multiple sclerosis.
Objective: This study explored the influence of depression and fatigue on subjective cognitive complaints and objective neuropsychological impairment in patients with multiple sclerosis (MS). Methods: Data for this study were taken from a randomized controlled trial, comparing 16 weeks of telephone-administered cognitive-behavioral therapy and telephone-administered supportive emotion focused therapy for the treatment of depression. The sample includes 127 patients with MS. The following self-report measures were collected pre- and posttreatment: Perceived Deficits Questionnaire, Beck Depression Inventory-II, and Modified Fatigue Impact Scale. Measures of objective cognitive functioning and the Hamilton Rating Scale for Depression were administered over the telephone. Results: Our results showed that changes in depression and fatigue significantly predicted changes in subjective cognitive complaints from pre- to posttreatment, with patients perceiving fewer cognitive problems at posttreatment (β = .36, p <.001 and β = .61, p <.001, respectively). Changes in depression and fatigue were not significantly related to changes in objective neuropsychological performance. Improvements in depression and fatigue also predicted improved accuracy in perceiving cognitive abilities from pre- to posttreatment (OR = .77, p <.001 and OR = .90, p <.001, respectively). Conclusions: The results of this study suggest that improvements in depression and fatigue through treatment do not influence objective neuropsychological performance in MS patients, but do relate to changes in subjective impairment. Furthermore, these changes improve patients' abilities to accurately perceive their cognitive functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
The nature of naming errors in primary progressive aphasia versus acute post-stroke aphasia.
Objective: To compare the distribution of error types across subgroups of primary progressive aphasia and poststroke aphasia in different vascular locations. Method: We analyzed naming errors in 49 individuals with acute left hemisphere ischemic stroke and 55 individuals with three variants of primary progressive aphasia. Location of atrophy or ischemic stroke was characterized using MRI. Results: We found that distribution of error types was very similar across all subgroups, irrespective of the site or etiology of the lesion. The only significant difference across groups was the percentage of circumlocutions (F(7, 96) = 3.02, p = .005). Circumlocution errors were highest among logopenic variant PPA (24%) and semantic variant PPA (24%). Semantic coordinate errors were common in all groups, probably because they can arise from disruption of different cognitive processes underlying naming and, therefore, from different locations of brain damage. Conclusions: Semantic errors are common among all types of primary progressive aphasia and poststroke aphasia, and the type of error depends in part on the location of damage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Executive function in individuals with subthreshold autism traits.
Objective: Recent research has documented increased psychosocial difficulties in individuals who report higher-than-typical autistic traits but without an Autism Spectrum Disorder (ASD) diagnosis. Less is known, however, regarding the cognitive profile of individuals with subthreshold autism symptomatology. The objective of the present study was to provide additional insight into this issue and examine whether young adults who report higher degrees of autism traits also report experiencing increased difficulties with executive control. Method: The Behavior Rating Inventory of Executive Function was utilized to evaluate behavioral aspects of executive functioning in 66 and 28 individuals who endorsed high and low subthreshold levels of autism symptomatology, respectively. Results: After accounting for Attention Deficit/Hyperactivity Disorder (ADHD) symptomatology at both the group and individual participant levels, we found that autism traits continued to explain a significant amount of variance in participants' overall level of executive function (Global Executive Composite) as well as within most individual executive domains. Interestingly, the high and low trait groups did not differ on the inhibitory control and organization of materials scales, areas of functioning that appears to be largely spared in individuals with ASD as well. Conclusions: Findings from the present study are consistent with past research linking ASD and executive control impairment. In addition, ASD and ADHD traits were associated with unique contributions to the executive control profile of individuals with subthreshold autism symptomatology. This finding underscores the importance of accounting for ADHD symptomatology in studying ASD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Recognition by familiarity is preserved in Parkinson's without dementia and Lewy-Body disease.
Objective: The retrieval deficit hypothesis states that the lack of deficit in recognition often observed in patients with Parkinson's disease is because of the low retrieval requirements of the task, given that these patients have retrieval and not encoding deficits. To test this hypothesis we investigated recognition memory by familiarity in Parkinson's patients and in patients with Lewy Bodies disease and Parkinson with dementia. Method: We analyzed to what extent the experimental groups were able to recognize by familiarity in a typical yes/no recognition memory task. The experimental groups were patients with early nondemented Parkinson's disease, advanced nondemented Parkinson's disease, demented Parkinson's patients, and patients with dementia with Lewy Bodies. We compared their performance with a group of young and another group of old healthy participants. The estimation of familiarity was made by analyzing recognition of word targets and distractors consisting of combinations of different letters in comparison with a condition in which targets and distractors were composed of similar letters, even though subjects were unaware of the independent variable. Results: The results indicate that familiarity was used at the same level by controls, patients with early Parkinson's disease and patients with dementia with Lewy Bodies. Although late Parkinson patients also used familiarity, its effect was only marginally significant. Patients with Parkinson's disease and dementia were not capable of using familiarity in recognition memory. Conclusions: Our results support the retrieval deficit hypothesis as Parkinson's patients without dementia show no deficit in a situation in which the retrieval requirements are minimal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Scene construction in schizophrenia.
Objective: Recent research has revealed that schizophrenia patients are impaired in remembering the past and imagining the future. In this study, we examined patients' ability to engage in scene construction (i.e., the process of mentally generating and maintaining a complex and coherent scene), which is a key part of retrieving past experiences and episodic future thinking. Method: 24 participants with schizophrenia and 25 healthy controls were asked to imagine new fictitious experiences and described their mental representations of the scenes in as much detail as possible. Descriptions were scored according to various dimensions (e.g., sensory details, spatial reference), and participants also provided ratings of their subjective experience when imagining the scenes (e.g., their sense of presence, the perceived similarity of imagined events to past experiences). Results: Imagined scenes contained less phenomenological details (d = 1.11) and were more fragmented (d = 2.81) in schizophrenia patients compared to controls. Furthermore, positive symptoms were positively correlated to the sense of presence (r = .43) and the perceived similarity of imagined events to past episodes (r = .47), whereas negative symptoms were negatively related to the overall richness of the imagined scenes (r = −.43). Conclusions: The results suggest that schizophrenic patients' impairments in remembering the past and imagining the future are, at least in part, due to deficits in the process of scene construction. The relationships between the characteristics of imagined scenes and positive and negative symptoms could be related to reality monitoring deficits and difficulties in strategic retrieval processes, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Age-related practice effects across longitudinal neuropsychological assessments in older people with schizophrenia.
Objective: The relationship between aging and practice effects on longitudinal neuropsychological assessments was investigated in middle-aged and older people with schizophrenia and healthy controls. Method: Older people with schizophrenia (n = 107; M age = 56.1) and age-comparable nonpsychiatric controls (n = 107; M age = 57.7) were scheduled to receive annual assessments on a comprehensive battery of neuropsychological tests for an average of 2.5 years (range 11 months to 4 years). Mixed-model analyses were used to separately examine the effects of practice and age on test performance. Results: Number of prior assessments (practice) was associated with significant performance improvement across assessments, whereas older age was associated with significant decline in performance. The groups did not differ significantly in extent of age-related cognitive decline, but a three-way interaction among group, age, and practice was found, such that greater age-related decline in practice effects were found for older people with schizophrenia relative to nonpsychiatric participants. Conclusions: This study did not find any evidence of neurodegenerative age-related decline in neuropsychological abilities in middle-aged and older people with schizophrenia, but older age was associated with diminished ability to benefit from repeated exposure to cognitive tasks in people with schizophrenia. Cognitive impairment in schizophrenia may combine with cognitive decline associated with normal aging to reduce practice effects in older patients. These findings have important implications for the design of studies examining the longitudinal trajectory of cognitive functioning across the life span of people with schizophrenia, as well as clinical trials that attempt to demonstrate cognitive enhancement in these individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Data-driven methodology illustrating mechanisms underlying word list recall: Applications to clinical research.
Objective: Word list learning tasks such as the California Verbal Learning Test (CVLT; Delis, Kramer, Kaplan, & Ober, 1987) are widely used to investigate recall strategies. Participants who recall the most words generally employ semantic techniques, whereas those with poor recall (e.g., patients with schizophrenia) rely on serial techniques. However, these conclusions are based on formulas that assume that categories reflect semantic associations, bind strategy to overall performance, and neglect strategy changes over 5 trials. Therefore, we derived novel measures—independent of recall performance—to compute strategies across trials and identify whether diagnosis predicts recall strategy. Method: Participants were included on the basis of performance on the CVLT (i.e., total words recalled over 5 trials). The 50 highest and 50 lowest performers among healthy volunteers (n = 100) and patients with schizophrenia (n = 100) were selected. Novel measures of recall and transition probability were calculated and analyzed by permutation tests. Results: Recall patterns and strategies of patients resembled those of controls with similar performance levels: Regardless of diagnosis, low performers were more likely to recall the first 2 and last 4 items from the list; high performers increased engagement of semantically based transitions across the 5 trials, whereas low performers did not. Conclusions: Cognitive strategy must be considered independent of overall performance before attributing poor performance to degraded learning processes. Our results demonstrate the importance of departing from global scoring techniques, especially when working with clinical populations such as patients with schizophrenia for whom episodic memory deficits are a hallmark feature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Appraising the ANT: Psychometric and theoretical considerations of the Attention Network Test.
Objective: The Attention Network Test (ANT) is a tool used to assess the efficiency of the 3 attention networks—alerting, orienting, and executive control. The ANT has become popular in the neuropsychological literature since its first description in 2002, with some form of the task currently appearing in no less than 65 original research papers. Although several general reviews of the ANT exist, none provide an analysis of its psychometric properties. Method: Data from 15 unique studies were collected, resulting in a large sample (N = 1,129) of healthy individuals. Split-half reliability, variance structure, distribution shape, and independence of measurement of the 3 attention network scores were analyzed, considering both reaction time and accuracy as dependent variables. Results: Split-half reliabilities of reaction time based attention network scores were low for alerting (rweighted = .20, CI 95%weighted [.14, .27], Spearman–Brown r = .38) and orienting (rweighted = .32, CI 95%weighted [.26, .38], Spearman–Brown r = .55), and moderate high for executive control (rweighted = .65, CI 95%weighted [.61, .71], Spearman–Brown r = .81). Analysis of the variance structure of the ANT indicated that power to find significant effects was variable across networks and dependent on the statistical analysis being used. Both analysis of variance (significant interaction observed in 100% of 15 studies) and correlational analyses (multiple-significant inter-network correlations observed) suggest that the networks measured by the ANT are not independent. Conclusions: In the collection, analysis and interpretation of any test data, psychometric properties, such as those reported here for the ANT, must be carefully considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Modeling the effects of hypoglycemia on a two-choice task in adult humans.
Objective: Previous research has demonstrated that hypoglycemia causes reaction times to be slower and more variable. Reaction time tests, however, use multiple cognitive and noncognitive processes. This study is the first to use a validated sequential sampling model (diffusion model) applied to results obtained from a simple 2-choice task in adult humans to assess the effects of hypoglycemia on the basic parameters of decision making. Method: Fourteen adult volunteers were tested on a numerosity discrimination task with and without reduced blood glucose concentrations. The results were analyzed with a model that dissects the components of processing that underlie decisions: the quality of the information on which a decision is based (drift rate), the critical amount of evidence that must be accumulated before a decision is made (boundary separation), and the time taken by nondecision processes. Results: Hypoglycemia resulted in a reduction of mean drift rate from 0.290 to 0.211, t(13) = 4.10, p <.05. No effect of experimental state was observed on the amount of evidence required to make a decision or peripheral and motor processes. Conclusion: This study locates the precise processing deficit associated with hypoglycemia and provides further understanding of the precise cognitive effect of hypoglycemia. Further research into the amelioration of these effects is required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Laterality effects for musical structure processing: A dichotic listening study.
Objective: Our study investigated hemispheric lateralization for musical structure processing using a dichotic listening paradigm with music and speech. Method: Eight chord sequences and 8 spoken syllable sequences were simultaneously presented, each to 1 ear. For the musical sequences, the final chord was expected (i.e., tonic) or less expected (i.e., subdominant). In addition to tonal function, which was task irrelevant, we manipulated the final syllable and the final timbre of the sequences for the experimental task: Participants were asked to identify the final syllable (/di/, /du/) or the timbre of the final chord (Timbre A or B). Results: Our experiment revealed a left-ear advantage for the tonal function effect on spoken syllable identification. For syllables presented to the right ear, identification was faster when the final chord of the musical sequence was a tonic chord rather than a subdominant chord (i.e., musical sequences presented to the left ear). Conclusions: The present finding extends the effect of musical structure previously observed for sung and visual syllable processing to spoken syllable processing. It further suggests a right-hemispheric specialization for the processing of musical structures in healthy listeners, as previously reported for split-brain patients (Tramo & Bharucha, 1991). (PsycINFO Database Record (c) 2010 APA, all rights reserved)
A pilot study of the neuropsychological benefits of computerized cognitive rehabilitation in Ugandan children with HIV.
Objective: Because antiretroviral treatment (ART) fails to improve neurocognitive impairment in children with HIV, we completed a pilot study evaluating the feasibility and cognitive benefit of computerized cognitive rehabilitation therapy (CCRT) in Ugandan children with HIV. Method: Sixty Ugandan children with HIV (23 on ART) were randomly assigned to 10 sessions of Captain's Log CCRT (Sandford, 2007) training configured for attention and memory skills or no intervention. Kaufman Assessment Battery for Children (2nd ed., KABC–2; Kaufman & Kaufman, 2004) performance at baseline indicated pervasive neurocognitive impairment. Cognitive ability was assessed before and after training using the Cogstate computerized neuropsychological test (Darby, Maruff, Collie, & McStephen, 2002). Viral load along with CD4 and CD8 absolute and activation levels also were measured posttest. Results: CCRT was well received with a 95% adherence rate to scheduled training sessions. CCRT intervention children showed greater improvement on a Cogstate card detection task of simple attention (p = .02), and speed of correct moves on a Groton Maze Learning Task (p <.001). These analyses were completed using an analysis of covariance model that adjusted Cogstate performance for the child's age, standardized weight for age, gender, socioeconomic status, school grade level, and baseline KABC–2 performance. ART treatment was not related to Cogstate performance or improvement as a result of CCRT. CD4 and CD8 activation levels were correlated with Cogstate improvement specifically for the CCRT group. Conclusions: CCRT was feasible with our study population and improved maze learning and attention on a detection task. This supports previous findings by our group with cerebral malaria survivors (Bangirana, Giordani, et al., 2009). (PsycINFO Database Record (c) 2010 APA, all rights reserved)
The role of vision in the Corsi Block-Tapping task: Evidence from blind and sighted people.
Objective: This study aims at adapting the Corsi Block-Tapping task to measure serial-spatial memory in blind people and at clarifying the role of visual experience in the task. Method: Congenitally blind, adventitiously blind, and blindfolded sighted people were compared on a version of the Corsi board that allowed the haptic perception of block positions (Haptic-Corsi). Participants placed their fingers on the blocks that the experimenter moved upward according to sequences of increasing length. Afterward, participants reproduced the sequences in forward/backward order. Results: The results showed a significant interaction between groups and forward/backward span: F(2, 58) = 5.74, MSE = .39, p <.01, η2 = .16. In forward order the memory span was higher in adventitiously blind participants than blindfolded sighted (p <.05) but not congenitally blind participants. In backward order, there were no significant differences. Conclusions: The good performance of blind people, especially adventitiously ones, was interpreted as evidence that sequential haptic inputs were organized spatially. The possible cognitive processes underlying the performance were discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)

Neuropsychology - Vol 24, Iss 5