Impaired Information Processing Speed Research Articles

Impaired information processing speed and attention allocation in multiple sclerosis patients versus controls: A high-density EEG study

BackgroundThe no-go P3a is a variant of the P300 event-related potential (ERP) that indexes speed of information processing and attention allocation. The aim of this study was to compare ERP findings with results from the paced auditory serial addition test (PASAT) and to quantify latency, amplitude and topographical differences in P3a ERP components between multiple sclerosis (MS) patients and controls. Patients and methodsSeventy-four subjects (20 relapsing remitting (RRMS) patients, 20 secondary progressive (SPMS) patients and 34 controls) completed a three-stimulus oddball paradigm (target, standard, and non-target). Subjects participated in separate visual and auditory tasks while data were recorded from 134 EEG channels. Latency differences were tested using an ANCOVA. Topographical differences were tested using statistical parametric mapping. ResultsVisual P3a amplitude correlated with PASAT score in all MS patients over frontal and parietal areas. There were significant differences in latency, amplitude, and topography between MS patients and controls in the visual condition. RRMS and SPMS patients differed in visual P3a latency and amplitude at frontal and parietal scalp regions. In the auditory condition, there were latency differences between MS patients and controls only over the parietal region. ConclusionThe present results demonstrate that information processing speed and attention allocation are impaired in MS.

Factors contributing to attentional impairments after traumatic brain injury.

The aim of the present study was to investigate the contribution of impaired information processing speed and strategic control of attention to performance on attentional tasks after traumatic brain injury (TBI). Forty moderately to severely injured rehabilitation inpatients and 40 healthy controls completed a selection of attentional tasks. Slowed processing speed in the TBI group was identified on the Symbol Digit Modalities Test (SDMT), 2&7 Selective Attention Test (2&7), Selective Attention (SAT), and Four Choice Reaction Time (4CRT) tasks. Impaired working memory was evident on the Letter Number Sequencing (LNS) task. Structural equation modeling revealed that the group difference in RT on the complex SAT was accounted for by slowed speed of processing on the simple SAT, and not working memory. TBI participants made more errors and missed responses on the complex version of the SAT, suggesting impairment in some aspects of strategic control of attention, and appeared unable to benefit from the automatic condition of the 2&7 Test. There was little evidence of deficit on the Sustained Attention to Response Task (SART). The present study provides evidence for a significant contribution of slowed processing speed to impaired performance on attentional tasks after TBI.

Impairments in fine-motor coordination and speed of information processing predict declines in everyday functioning in hepatitis C infection

Research increasingly supports the neurovirulence of chronic infection with the hepatitis C virus (HCV). For example, HCV infection has been associated with neuropsychological impairment in several ability areas, including psychomotor skills. This study aimed to examine whether HCV-associated neuropsychological impairment is predictive of declines in the independent performance of physical (PADLs) and instrumental (IADLs) activities of daily living. A total of 106 volunteers with HCV infection completed a comprehensive neuropsychological, medical, and psychiatric research evaluation. As compared to 30 HCV-seronegative comparison participants, the HCV-infected group reported significantly greater declines in both PADLs and IADLs. Within the HCV cohort, individuals with impaired speed of information processing reported significantly greater IADL declines, whereas impaired fine-motor coordination was associated with declines in both IADLs and PADLs. In a series of regression analyses, impaired speed of information processing and depressive symptoms (as measured by the Beck Depression Inventory) were the only independent predictors of IADL declines, whereas general affective distress (as measured by the Profile of Mood States), sex, and fine-motor coordination impairment were predictive of declines in PADLs. Although the clinical assessment of HCV typically emphasizes both affective (e.g., depression) and physical factors, findings from the present study suggest that cognitive impairment is an important contributor to everyday functioning in persons living with HCV infection and therefore warrants consideration in clinical and research evaluations.

Neuropsychologic and Functional Outcome After Complicated Mild Traumatic Brain Injury

Kashluba S, Hanks RA, Casey JE, Millis SR. Neuropsychologic and functional outcome after complicated mild traumatic brain injury. Objective To investigate the extent to which neuropsychologic and functional outcome after complicated mild traumatic brain injury (TBI) parallels that of moderate TBI recovery. Design A longitudinal study comparing neuropsychologic and functional status of persons with complicated mild TBI and moderate TBI at discharge from inpatient rehabilitation and at 1 year postinjury. Setting Rehabilitation hospital with a Traumatic Brain Injury Model System. Participants Persons with complicated mild TBI (n=102), each with an intracranial brain lesion documented through neuroimaging and a highest Glasgow Coma Scale (GCS) score in the emergency department between 13 and 15, and 127 persons with moderate TBI. Interventions Not applicable. Main Outcome Measures FIM instrument, Disability Rating Scale, Community Integration Questionnaire, Wechsler Memory Scale logical memory I and II, Rey Auditory Verbal Learning Test, Trail-Making Test, Controlled Oral Word Association Test, Symbol Digit Modalities Test, Wisconsin Card Sorting Test, and block design. Results Few differences in neuropsychologic performance existed between the TBI groups. Less severely impaired information processing speed and verbal learning were seen in the complicated mild TBI group at rehabilitation discharge and 1 year postinjury. Despite overall improvement across cognitive domains within the complicated mild TBI group, some degree of impairment remained at 1 year postinjury on those measures that had identified participants as impaired soon after injury. No differences on functional ability measures were found between the TBI groups at either time period postinjury, with both groups exhibiting incomplete recovery of functional status at the 1-year follow-up. Conclusions When classifying severity of TBI based on GCS scores, consideration of a moderate injury designation should be given to persons with an intracranial bleed and a GCS score between 13 and 15.

Long-term psychiatric disorders after traumatic brain injury

In the long term after traumatic brain injury, the most disabling problems are generally related to neuropsychiatric sequelae, including personality change and cognitive impairment, rather than neurophysical sequelae. Cognitive impairment after severe injury is likely to include impaired speed of information processing, poor memory and executive problems. Personality change may include poor motivation, and a tendency to be self-centred and less aware of the needs of others. Patients may be described as lazy and thoughtless. Some become disinhibited and rude. Agitation and aggression can be very difficult to manage. Anxiety and depression symptoms are quite frequent and play a role in the development of persistent post-concussion syndrome after milder injury. Depression may be associated with a deterioration in disability over time after injury. Psychosis is not unusual though it has been difficult to confirm that traumatic brain injury is a cause of schizophrenia. Head injury may, many years later, increase the risk of Alzheimer's disease. Good rehabilitation probably minimizes the risk of psychiatric sequelae, but specific psychological and pharmacological treatments may be needed.

Concurrent Validity of the PASAT and Adjusting-PSAT in Patients with Multiple Sclerosis

Impaired information processing speed (IPS) is common in multiple sclerosis (MS). Performance on the Paced Auditory Serial Addition Test (PSAT)—the measure recommended by the United States National MS Society Task Force to track changes in IPS—does not indicate the precise speed at which IPS breaks down. A newer version of the task, the Adjusted Paced Serial Addition Test (A-PSAT), provides such an index. This study examined the relationship between PASAT and A-PSAT performance in a sample of 52 individuals with MS. Those with relapsing-remitting MS (RRMS) were significantly younger and had significantly lower EDSS scores than those with chronic progressive MS (CPMS). Though performance indicators for both the PASAT and A-PSAT were better for patients with RRMS, differences in performance between MS groups were not significant (P >.05). Results of comparisons between the A-PSAT and PASAT support concurrent validity of the A-PSAT. In addition, performance on the APSAT—but not the PASAT—was significantly related to functional status as measured by the EDSS. Although these findings need to be replicated, they indicate that the A-PSAT may be a viable alternative to the existing PASAT.

Within session practice effects on the PASAT in clients with multiple sclerosis

Impaired information processing speed (IPS) is common in multiple sclerosis (MS). As a measure of IPS the Paced Auditory Serial Addition Test (PASAT), the measure recommended for serial assessments by the National MS Society Task Force, is influenced by practice effects. Within session practice effects for the PASAT were examined in a sample of 30 individuals with MS. Significant practice effects on all PASAT trials were identified, with the exception of the slowest trial. Those with relapsing-remitting MS showed greater improvement on repeated assessment than those with chronic-progressive MS, on all except the slowest PASAT trial. It was concluded that, due to the extensive practice effects found at faster presentation, serial use of the PASAT in MS samples should either rely on use of slower presentations, or include some correction to account for practice effects.

Neuropsychological assessment in MS: clinical, neurophysiological and neuroradiological relationships.

We assessed cognitive performance and its relationship with clinical and anatomic disease severity in MS with mild to moderate handicap; 34 definite MS and 18 healthy subjects matched for age and education were submitted to a neuropsychological test battery. Both groups were examined for anxiety. MS patients underwent magnetic resonance imaging examination. MS performed worse than controls on all WAIS-P subtests and had learning, short- and long-term verbal memory impairment. Cognitive deficits were not related to abnormal emotional states, but were found to be associated with attentional process and information-processing speed impairment. Cognitive impairment did not correlate with severity of physical disability. The most severe memory deficits were found in patients with extensive periventricular damage.

Impaired Speed of Information Processing in Nonmedicated Schizotypal Patients

There is increasing evidence that schizophrenia is associated with an attentional or information processing deficit or both. These "early deficit" theories challenge the position that schizophrenia is primarily a disorder of thinking and higher cognitive operations. A tachistoscopic backward masking task was applied in matched groups of 20 schizophrenic, 20 schizotypal, and 20 depressive psychiatric inpatients. Resulting data are an index of visual input factors and speed of information processing. Paranoid schizophrenic and schizotypal subjects had unimpaired visual input thresholds but abnormally slow processing compared with the depressives. Since all the schizotypal subjects were nonmedicated, the data add important support to the hypothesis that impaired speed of information processing in schizophrenia spectrum disorders is due to schizophrenia per se and is not secondary to medication effects. These data also support the theoretical link between schizophrenic and schizotypal patients. The importance of the results is discussed, with emphasis on the hypothesized relationship between information processing dysfunction and symptom formation in the schizophrenias.