Decreased Processing Speed Research Articles

Assessment of cognitive rehabilitation in adults with cerebral palsy

To date, there is very little data available regarding cognitive functioning in adults with cerebral palsy. A research has been coordinated since 2012 by the network “Réseau Breizh paralysie cérébrale”. During its first phase, the research has established that the study population profile was characterized by a decreased processing speed, visuo-constructive problems and working memory impairment. The ongoing second phase aims at assessing the impact of a cognitive management on those disorders. The research includes 18 ICP patients with reading and writing skills (lower secondary school; 2-year post-baccalaureat level), who expressed a cognitive complaint. The first phase of the assessment highlighted the neuropsychological profile of each patient. Among the 18 patients, with an average age of 28 years old [18; 50], 10 participated in a 6-month cognitive intervention, aimed at the disorders which were previously identified. A comparative assessment was conducted 9 to 12 months after the first one, in all patients. The patients mentioned a better functioning in their daily life (awareness of the disorders, etc.). The analysis shows that the performance improved in some areas. A comparative analysis was conducted between the patient group which participated at the cognitive intervention and the group which didn’t.

Differences in cognitive aging: typology based on a community structure detection approach.

The current study investigated the extent and patterns of cognitive variability in younger and older adults. An important novelty of this study is the use of graph-based community structure detection analysis to map performance in a mixed population of 79 young and 76 older adults, without separating the age groups a-priori. We identified six subgroups, with distinct patterns of neuropsychological performance. The stability of the identified subgroups was confirmed by employing a cross-validation support vector machine based analysis. The majority of these subgroups comprised either young or older adults, confirming the expected role of aging in cognitive performance. In addition, we identified a subgroup of young and older adults who performed at a similar cognitive level of overall good cognitive performance with slightly decreased processing speed. This result showed that older age is not necessarily associated with general lower cognitive performance and that being young is not necessarily associated with superior cognitive performance. Moreover, cognitively better performing elderly had a significantly higher level of education attainment and higher crystallized intelligence than the other elderly, which suggests that older adults with higher cognitive reserve may be able to cope better with age-related neurobiological change.

Reversible cognitive, motor, and driving impairments in severe hypothyroidism.

Hypothyroidism has been associated with cognitive and motor impairments that are likely to constitute hazards in the operation of motor vehicles and a public safety risk. However, there is a paucity of data that would provide an evidence basis for recommendations to hypothyroid patients. The purpose of this study was to determine the specific neurological and psychological deficits consequent to hypothyroidism and whether they are of sufficient magnitude to impede the safe operation of motor vehicles. Repeated measurements were obtained in euthyroid, hypothyroid, and euthyroid hormone replaced states of thyroid cancer outpatients, at an academic medical center, who underwent thyroid hormone withdrawal preparation for radioiodine scanning. Study design used a within-subjects longitudinal "A-B-A" with each subject tested at three visits in the same sequence: euthyroid, hypothyroid, and euthyroid for a total of 32 subjects. Data on clinical status and cognitive performance were collected using standard instruments, including ThyDQoL and ThySRQ measures, National Adult Reading Test, Boston Naming Test, Mini-Mental State Exam, Wechsler Adult Intelligence Test-Revised, Letter Fluency FAS, and Beck Depression Inventory. Fine-motor function was measured with an automated assessment panel, and driving performance on a commercial driving simulator. In severe hypothyroidism (median thyrotropin 83.2 mIU/L), fine-motor performance of hands and reaction times in emergency braking tests were slowed, as well as subjective slowing reported on structured clinical scales. Depression was present, typified by vegetative and mood alterations, but lacking reported guilt and lowered self-esteem seen in other types of depression. Cognitive impairment was characterized by declines on speeded executive tests. In contrast, episodic memory performance improved over time regardless of thyroid hormone status. Braking times increased in hypothyroidism by 8.5%, equivalent to reports of effects from a blood alcohol level of 0.082 g/100 mL (above the U.S. legal driving limit). Transient profound hypothyroidism is characterized by reversible depression, decreased fine-motor performance, slowed reaction times, and decreased processing speed. These data represent new empirical evidence that support the recommendation that complex activities requiring rapid responses, such as operating motor vehicles, should be avoided during hypothyroidism. This has broader implications regarding functional impairments and risk to public health.

Visual encoding impairment in patients with schizophrenia: contribution of reduced working memory span, decreased processing speed, and affective symptoms.

Previous research has revealed the contribution of decreased processing speed and reduced working memory span in verbal and visual memory impairment in patients with schizophrenia. The role of affective symptoms in verbal memory has also emerged in a few studies. The authors designed a picture recognition task to investigate the impact of these factors on visual encoding. Two types of pictures (black and white vs. colored) were presented under 2 different conditions of context encoding (either displayed at a specific location or in association with another visual stimulus). It was assumed that the process of encoding associated pictures was more effortful than that of encoding pictures that were presented alone. Working memory span and processing speed were assessed. In the patient group, working memory span was significantly associated with the recognition of the associated pictures but not significantly with that of the other pictures. Controlling for processing speed eliminated the patients' deficit in the recognition of the colored pictures and greatly reduced their deficit in the recognition of the black-and-white pictures. The recognition of the black-and-white pictures was inversely related to anxiety in men and to depression in women. Working memory span constrains the effortful visual encoding processes in patients, whereas processing speed decrement accounts for most of their visual encoding deficit. Affective symptoms also have an impact on visual encoding, albeit differently in men and women.

The role of executive control in bilingual language production: A study with Parkinson's disease individuals

The basal ganglia are critically involved in language control (LC) processes, allowing a bilingual to utter correctly in one language without interference from the non-requested language. It has been hypothesized that the neural mechanism of LC closely resembles domain-general executive control (EC). The purpose of the present study is to investigate the integrity of bilingual LC and its overlap with domain-general EC in a clinical population such as individuals with Parkinson's disease (PD), notoriously associated with structural damage in the basal ganglia.We approach these issues in two ways. First, we employed a language switching task to investigate the integrity of LC in a group of Catalan–Spanish bilingual individuals with PD, as compared to a group of matched healthy controls. Second, to test the relationship between domain-general EC and LC we compared the performances of individuals with PD and healthy controls also in a non-linguistic switching task. We highlight that, compared to controls, individuals with PD report decreased processing speed, less accuracy and larger switching costs in terms of RT and errors in the language switching task, whereas in the non-linguistic switching task PD patients showed only increased switching cost in terms of errors. However, we report a positive correlation between the magnitudes of linguistic and non-linguistic mixing costs in individuals with PD. Taken together, these results support the notion of a critical role of the basal ganglia and connected structures in LC, and suggest a possible link between LC and domain-general EC.

Decreased processing speed might account for working memory span deficit in schizophrenia, and might mediate the associations between working memory span and clinical symptoms

Verbal working memory span is decreased in patients with schizophrenia, and this might contribute to impairment in higher cognitive functions as well as to the formation of certain clinical symptoms. Processing speed has been identified as a crucial factor in cognitive efficiency in this population. We tested the hypothesis that decreased processing speed underlies the verbal working memory deficit in patients and mediates the associations between working memory span and clinical symptoms. Forty-nine schizophrenia inpatients recruited from units for chronic and acute patients, and forty-five healthy participants, were involved in the study. Verbal working memory span was assessed by means of the letter-number span. The Digit Copy test was used to assess motor speed, and the Digit Symbol Substitution Test to assess cognitive speed. The working memory span was significantly impaired in patients (F(1,90)=4.6, P<0.05). However, the group difference was eliminated when either the motor or the cognitive speed measure was controlled (F(1,89)=0.03, P=0.86, and F(1,89)=0.03, P=0.88). In the patient group, working memory span was significantly correlated with negative symptoms (r=-0.52, P<0.0001) and thought disorganisation (r=-0.34, P<0.025) scores. Regression analyses showed that the association with negative symptoms was no longer significant when the motor speed measure was controlled (β=-0.12, P=0.20), while the association with thought disorganisation was no longer significant when the cognitive speed measure was controlled (β=-0.10, P=0.26). Decrement in motor and cognitive speed plays a significant role in both the verbal working memory impairment observed in patients and the associations between verbal working memory impairment and clinical symptoms.

Detection of central white matter injury underlying vestibulopathy after mild traumatic brain injury.

To determine if central axonal injury underlies vestibulopathy and ocular convergence insufficiency after mild traumatic brain injury (TBI) by using tract-based spatial statistics (TBSS) analysis of diffusion-tensor imaging (DTI). The institutional review board approved this study, and the requirement to obtain informed consent was waived. Diffusion-tensor images were retrospectively reviewed in 30 patients with mild TBI and vestibular symptoms and 25 patients with mild TBI and ocular convergence insufficiency. Control subjects consisted of 39 patients with mild TBI without vestibular abnormalities and 17 patients with mild TBI and normal ocular convergence. Fractional anisotropy (FA) maps were generated as a measure of white matter integrity and were analyzed with TBSS regression analysis by using a general linear model. DTI abnormalities were correlated with symptom severity, neurocognitive test scores, and time to recovery with the Pearson correlation coefficient. Compared with control subjects, patients with mild TBI and vestibular symptoms had decreased neurocognitive test scores (P < .05) and FA values in the cerebellum and fusiform gyri (P < .05). Patients with ocular convergence insufficiency had diminished neurocognitive test scores (P < .05) and FA values in the right anterior thalamic radiation and right geniculate nucleus optic tracts (P < .0001). Cerebellar injury showed an inverse correlation with recovery time (R = -0.410, P = .02). Anterior thalamic radiation injury showed correlation with decreased processing speed (R = 0.402, P < .05). DTI findings in patients with mild TBI and vestibulopathy support the hypothesis that posttraumatic vestibulopathy has a central axonal injury component. Peripheral vestibular structures were not assessed, and a superimposed peripheral contribution may exist. DTI evaluation of central vestibular structures may provide a diagnostic imaging tool in these patients and a quantitative biomarker to aid in prognosis.

Biomarkers and neurodevelopment in perinatally HIV-infected or exposed youth

To examine the relationship between markers of vascular dysfunction and neurodevelopmental outcomes in perinatally HIV-infected (PHIV+) and perinatally HIV-exposed but uninfected (PHEU) youth. Cross-sectional design within a prospective, 15-site US-based cohort study. Neurodevelopmental outcomes were evaluated in relation to nine selected vascular biomarkers in 342 youth (212 PHIV+, 130 PHEU). Serum levels were assessed for adiponectin, C-reactive protein (CRP), fibrinogen, interleukin-6 (IL-6), soluble vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sE-selectin), monocyte chemoattractant protein (sMCP-1), intercellular adhesion molecule-1 (sICAM-1), and P-selectin (sP-selectin). The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) was administered at entry, yielding a Full-Scale IQ score, and four index scores. Factor analysis was conducted to reduce the biomarkers to fewer factors with related biological roles. Structural equation models (SEMs) were used to measure associations between resulting factors and WISC-IV scores. Mean participant age was 11.4 years, 54% were female, 70% black. The nine biomarkers were clustered into three factor groups: F1 (fibrinogen, CRP, and IL-6); F2 (sICAM-1 and sVCAM-1); and F3 (MCP-1, sP-selectin, and sE-selectin). Adiponectin showed little correlation with any factor. SEMs revealed significant negative association of F1 with WISC-IV processing speed score in the total cohort. This effect remained significant after adjusting for HIV status and other potential confounders. A similar association was observed when restricted to PHIV+ participants in both unadjusted and adjusted SEMs. Aggregate measures of fibrinogen, CRP, and IL-6 may serve as a latent biomarker associated with relatively decreased processing speed in both PHIV+ and PHEU youth.

White matter hyperintensities are associated with visual search behavior independent of generalized slowing in aging

A fundamental controversy is whether cognitive decline with advancing age can be entirely explained by decreased processing speed, or whether specific neural changes can elicit cognitive decline, independent of slowing. These hypotheses are anchored by studies of healthy older individuals where age is presumed the sole influence. Unfortunately, advancing age is also associated with asymptomatic brain white matter injury. We hypothesized that differences in white matter injury extent, manifest by MRI white matter hyperintensities (WMH), mediate differences in visual attentional control in healthy aging, beyond processing speed differences. We tested young and cognitively healthy older adults on search tasks indexing speed and attentional control. Increasing age was associated with generally slowed performance. WMH were also associated with slowed search times independent of processing speed differences. Consistent with evidence attributing reduced network connectivity to WMH, these results conclusively demonstrate that clinically silent white matter injury contributes to slower search performance indicative of compromised cognitive control, independent of generalized slowing of processing speed.

Predominant negative symptoms in 22q11.2 deletion syndrome and their associations with cognitive functioning and functional outcome

22q11.2 deletion syndrome (22q11.2DS) is a neurogenetic condition associated with increased risk for schizophrenia. No study do date has explored how positive and negative symptoms of psychosis are distributed among individual patients with 22q11.2DS and if distinct patterns of symptoms can be identified. Negative symptoms being more frequent than positive symptoms in 22q11.2DS, we expected that a high number of patients would display predominant negative symptoms (PNS), whereas predominant positive symptoms would be less frequently reported. The present study aims at investigating the cognitive deficits and functional outcome associated with distinct patterns of psychotic symptoms in 22q11.2DS. 63 adolescents and young adults with 22q11.2DS participated in this study. Each participant underwent a clinical and a cognitive evaluation. A cluster analysis was used to identify groups of individuals with distinct patterns of symptoms. Individuals from the different clusters were then compared on a series of cognitive measures and on functional outcome. Three clusters of individuals were identified: low levels of symptoms, PNS, and high levels of symptoms. Individuals with PNS had significantly lower visual memory scores and decreased processing speed compared to participants with low levels of symptoms. They were also rated as having lower functional and occupational outcome. The present results indicate that one third of adolescents and young adults with 22q11.2DS display PNS. This pattern of symptoms was associated with specific cognitive deficits and decreased functional outcome. Future studies are needed to examine the developmental trajectories of these individuals and assess their risk of conversion to full-blown psychosis.

Neurocognitive Functioning of Individuals With Schizophrenia: Using and Not Using Drugs

Research on neurocognition in schizophrenia, using modest samples and self-rated assessments, reports drug use contributes to improved rather than impaired cognitive function. We have sought to replicate these findings in a large sample of patients that had their drug-use status confirmed by laboratory assays and evaluated the potential differences in cognitive function between patients with positive and negative results. Nine hundred and seventy four schizophrenia patients completed neuropsychological and laboratory tests at screening/baseline of the Clinical Antipsychotic Trials of Intervention Effectiveness study. Radioimmunoassay (RIA) of hair tested for cannabis, cocaine and methamphetamine. Many patients screened positive for drug use (n = 262; 27%), and there were no differences between patients with positive and negative results in terms of cognitive function after adjusting for multiple inference testing, except patients with positive RIA for methamphetamine demonstrated increased processing speed (corrected, P = .024). Moderator models were employed to explore potential subgroup differences in this pattern of results. At low medication dosages, patients with positive RIA for cocaine demonstrated decreased processing speed compared with patients with negative RIA for cocaine (uncorrected, P = .008). And for any other drugs with low psychopathology, patients with positive RIA demonstrated decreased working memory compared with patients with negative RIA (uncorrected, P = .006). No positive effects of cannabis on cognitive function were observed, and drug use was not associated with improved neurocognition across most of the subgroup characteristics explored in this sample of schizophrenia patients.

Current Opinions on Epidemiology, Treatment and Outcome After Traumatic Brain Injury

Objective: The objective of this article is to provide an overview on current incidences of traumatic brain injury (TBI) with special focus on current surgical and non-surgical treatment options as well as outcome. Method: A Medline database search was performed using various combinations of the search terms “traumatic brain injury”, “TBI”, “treatment”, “outcome” “pediatric”, “intracranial hypertension”, “epidemiology” and “incidence”. Results: We found an incidence of TBI of 332/100,000 inhabitants in Germany per year and 219-345/100,000 TBI occurring in children. TBI is still the leading cause of mortality and morbidity worldwide. The overall mortality after TBI is described with 1%. Typical symptoms of TBI represent headache, nausea and vomiting, dizziness, blurred vision, paresis, aphasia, seizures and impaired coordination on the physical side. Cognitive impairments include attention, memory and concentration disorders or decreased processing speed whereas behavioural symptoms present as depression, anxiety, agitation or aggression. Persistence of these symptoms results in a vicious cycle of impaired skill acquisition and an adaptive deficit with increased academic failure, unemployment and loss of salary, social and behavioural dysfunction and isolation. The injury severity of TBI is commonly classified according to the established Glasgow Coma Scale (GCS) and the TCDB classification in CT-Scans. Established non-surgical treatment of intracranial pressure after TBI emphasizes on hyperventilation, hypothermia as well as application of mannitol, hypertonic saline solution or barbiturates. Recently, neuroprotective effects of erythropoietin (EPO) have been demonstrated. Surgical therapy consists of lumbar drainage of cerebrospinal fluid, decompressive craniotomy, and the evacuation of mass lesions. Conclusion: While scientific data concerning the classification of TBI, treatment and outcome prediction has significantly progressed over the last two decades identifying risk factors and treatment options, further research is needed consolidating first-, second- and third-tier treatment. Identifying treatment pathways based upon potential predictive factors and rehabilitative outcome is thought to improve family support of patients concerned and to optimize health care requirements.

Processing Speed and Working Memory Span: Their Differential Role in Superficial and Deep Memory Processes in Schizophrenia

Previous work has suggested that decrement in both processing speed and working memory span plays a role in the memory impairment observed in patients with schizophrenia. We undertook a study to examine simultaneously the effect of these two factors. A sample of 49 patients with schizophrenia and 43 healthy controls underwent a battery of verbal and visual memory tasks. Superficial and deep encoding memory measures were tallied. We conducted regression analyses on the various memory measures, using processing speed and working memory span as independent variables. In the patient group, processing speed was a significant predictor of superficial and deep memory measures in verbal and visual memory. Working memory span was an additional significant predictor of the deep memory measures only. Regression analyses involving all participants revealed that the effect of diagnosis on all the deep encoding memory measures was reduced to non-significance when processing speed was entered in the regression. Decreased processing speed is involved in verbal and visual memory deficit in patients, whether the task require superficial or deep encoding. Working memory is involved only insofar as the task requires a certain amount of effort.

Beta-amyloid deposition is associated with decreased processing speed and working memory but not reasoning or episodic memory in a highly screened healthy lifespan sample

Event Abstract Back to Event Beta-amyloid deposition is associated with decreased processing speed and working memory but not reasoning or episodic memory in a highly screened healthy lifespan sample Denise C. Park1*, Kristen M. Kennedy1, Karen M. Rodrigue1, Rieck R. Jennifer1, Blair Flicker1 and Michael D. Devous1 1 University of Texas at Dallas, United States Significant beta-amyloid deposition is seen in 20-30% of non-demented older adults. The cognitive sequelae of this deposition, however, remain unclear. The goal of the current study was to examine the association of cortical beta-amyloid deposition on various domains of cognitive performance that are typically sensitive to aging in a highly screened, lifespan sample of healthy adults. Participants (n = 88, aged 44-89) were scanned by PET using 18F-AV-45 which binds to amyloid plaques and were administered a range of cognitive tests. Cognitive construct composites with two or more measures each were calculated for speed of processing, working memory, reasoning, and episodic memory. Standardized uptake value ratios (SUVRs) were obtained from a priori masked regions of interest including anterior and posterior cingulate, precuneus, lateral temporal, frontal, parietal, and occipital cortices. We found that processing speed and working memory capacity were both reduced in individuals with greater amyloid burden, independent of the age effects on those cognitive domains. In contrast, reasoning and episodic memory were not associated with beta-amyloid burden beyond the effects of aging. Thus, beta-amyloid burden appears to exert an effect on the most basic cognitive measures (speed and working memory) whereas higher order cognition appears to be more protected from the effects of amyloid (verbal memory and reasoning). Funding: Supported in part by NIH grants 5R37AG-006265-25, 3R37AG-006265-25S1, and Alzheimer’s Association grant IIRG-09-135087. Keywords: Aging, PET Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Symposium: Oral Presentation Topic: Symposium 22: Successful aging: a neurocognitive perspective Citation: Park DC, Kennedy KM, Rodrigue KM, Jennifer RR, Flicker B and Devous MD (2011). Beta-amyloid deposition is associated with decreased processing speed and working memory but not reasoning or episodic memory in a highly screened healthy lifespan sample. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00594 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 14 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Denise C Park, University of Texas at Dallas, Texas, United States, denise@utdallas.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Denise C Park Kristen M Kennedy Karen M Rodrigue Rieck R Jennifer Blair Flicker Michael D Devous Google Denise C Park Kristen M Kennedy Karen M Rodrigue Rieck R Jennifer Blair Flicker Michael D Devous Google Scholar Denise C Park Kristen M Kennedy Karen M Rodrigue Rieck R Jennifer Blair Flicker Michael D Devous PubMed Denise C Park Kristen M Kennedy Karen M Rodrigue Rieck R Jennifer Blair Flicker Michael D Devous Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Cerebellar-Dependent Eyeblink Conditioning Deficits in Schizophrenia Spectrum Disorders

Accumulating evidence suggests that abnormalities in neural circuitry and timing associated with the cerebellum may play a role in the pathophysiology of schizophrenia. Schizotypal personality disorder (SPD) may be genetically linked to schizophrenia, but individuals with SPD are freer from potential research confounds and may therefore offer insight into psychophysiological correlates of schizophrenia. The present study employed a delay eyeblink conditioning (EBC) procedure to examine cerebellar-dependent learning in schizophrenia, SPD, and healthy control subjects (n = 18 per group) who were matched for age and gender. The conditioned stimulus was a 400-ms tone that coterminated with a 50 ms unconditioned stimulus air puff. Cognitive performance on the Picture Completion, Digit Symbol Coding, Similarities, and Digit Span subscales of the Wechsler Adult Intelligence Scale--Third Edition was also investigated. The schizophrenia and SPD groups demonstrated robust EBC impairment relative to the control subjects; they had significantly fewer conditioned responses (CRs), as well as smaller CR amplitudes. Schizophrenia subjects showed cognitive impairment across subscales compared with SPD and control subjects; SPD subjects showed intermediate performance to schizophrenia and control subjects and performed significantly worse than controls on Picture Completion. Impaired EBC was significantly related to decreased processing speed in schizophrenia spectrum subjects. These findings support the role of altered cortico-cerebellar-thalamic-cortical circuitry in the pathophysiology of schizophrenia spectrum disorders.

Cognition and the Risk of Hospitalization for Serious Falls in the Elderly: Results From the Cardiovascular Health Study

Many elderly adults fall every year, sometimes resulting in serious injury and hospitalization. Although impaired cognition is a risk factor for injurious falls, little is known about cognitive decline above the threshold of impairment and risk of serious falls in community-dwelling seniors. In total, 702 of 5,356 older adults participating in the Cardiovascular Health Study experienced an injurious fall between 1990 and 2005, as indicated by hospitalization records. General cognition was measured annually with the Modified Mini-Mental State Examination and processing speed with the Digit Symbol Substitution Test. The Cox regression model was used to calculate hazard ratio and 95% confidence interval with and without time-dependent covariates and adjusted for known risk factors. Participants with slightly decreased Digit Symbol Substitution Test scores were at increased risk for a serious fall (hazard ratio = 1.58, 95% confidence interval = 1.15-2.17). The risk continued to increase with each quartile decrease in Digit Symbol Substitution Test score. Participants without prevalent cardiovascular disease at baseline and decreased Modified Mini-Mental State Examination scores (80-89) had a 45% increased risk for a serious fall and those at high risk for dementia (<80) were at twice the risk as participants scoring above 90 (hazard ratio = 2.16, 95% confidence interval = 1.60-2.91). Both decreased general cognition and decreased processing speed appear to be potential risk factors for serious falls in the elderly. When assessing the risk of serious falls in elderly patients, clinicians should consider usual factors like gait instability and sensory impairment as well as less obvious ones such as cardiovascular disease and cognitive function in nondemented adults.

Executive functioning and processing speed in age-related differences in memory: Contribution of a coding task

The aim of the present study was to examine executive dysfunctioning and decreased processing speed as potential mediators of age-related differences in episodic memory. We compared the performances of young and elderly adults in a free-recall task. Participants were also given tests to measure executive functions and perceptual processing speed and a coding task (the Digit Symbol Substitution Test, DSST). More precisely, we tested the hypothesis that executive functions would mediate the age-related differences observed in the free-recall task better than perceptual speed. We also tested the assumption that a coding task, assumed to involve both executive processes and perceptual speed, would be the best mediator of age-related differences in memory. Findings first confirmed that the DSST combines executive processes and perceptual speed. Secondly, they showed that executive functions are a significant mediator of age-related differences in memory, and that DSST performance is the best predictor.

Working Memory Span and Motor and Cognitive Speed in Schizophrenia

The aim of this study was to investigate the verbal working memory deficit and decrease of motor and cognitive speed in patients with schizophrenia, and to clarify their associations with negative and depressive symptomatology. Forty patients with schizophrenia and 41 healthy control individuals were administered the backward digit span to assess the working memory capacity, along with 3 tests of processing speed. Patients demonstrated reduced backward digit span, as well as decreased motor and cognitive speed. Regression analyses indicated that the backward digit span was associated with cognitive speed. It was not associated with either negative or depressive symptoms. Decreased processing speed was unrelated to negative symptoms, but the depression score was significantly associated with the cognitive speed measure. Working memory and processing speed seem to share a cognitive component. Depression, but not negative symptoms, affects processing speed, especially by decreasing cognitive speed.

Role of processing speed and premorbid IQ on visual recognition in patients with schizophrenia

Previous research had shown that processing speed and premorbid IQ are predictors of verbal-memory efficiency in patients with schizophrenia. We investigated whether the same factors are involved in visual memory. A total of 49 patients with schizophrenia and 43 healthy controls were administered a picture recognition task. Half of the pictures were black and white, and half were in color, in order to vary the depth of encoding. Processing speed was measured by three standard tasks, and premorbid IQ was measured by the National Adult Reading Test (NART). Patients were significantly impaired in picture recognition. Regression analyses revealed that NART score was a significant predictor of the recognition of both types of picture in patients. Processing speed was a significant predictor of the recognition of the colored pictures. The effect of diagnosis on the recognition of colored pictures was reduced to nonsignificance when processing speed was entered in the regression. These data suggest that premorbid IQ is involved in visual-recognition efficiency. However, the deficit observed in patients is accounted for by decreased processing speed.

Aging white matter and cognition: Differential effects of regional variations in diffusion properties on memory, executive functions, and speed

Disruption of cerebral white matter has been proposed as an explanation for age-related cognitive declines. However, the role of specific regions in specific cognitive declines remains unclear. We used diffusion tensor imaging to examine the associations between regional microstructural integrity of the white matter and performance on age-sensitive cognitive tasks in a sample of healthy adults ( N = 52, age 19–81 years). White matter integrity was assessed by fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in multiple regions of interest (genu and splenium of corpus callosum, internal capsule limbs, prefrontal, temporal, superior/posterior parietal, occipital white matter) and related to processing speed, working memory, inhibition, task switching, and episodic memory. We found that age and regional white matter integrity differentially influenced cognitive performance. Age-related degradation in anterior brain areas was associated with decreased processing speed and poorer working memory, whereas reduced inhibition and greater task switching costs were linked to decline in posterior areas. Poorer episodic memory was associated with age-related differences in central white matter regions. The observed multiple dissociations among specific age-sensitive cognitive skills and their putative neuroanatomical substrates support the view that age-related cognitive declines are unlikely to stem from a single cause.