Christopher I. Higginson

Metamemory and tested cognitive functioning in multiple sclerosis.

Metamemory, or ones knowledge and self-report of memory ability, has been researched extensively; however, few studies have examined it in multiple sclerosis (MS). Because impairment in cognitive domains besides memory may affect memory functioning, patients may self-report problems with memory that are indicative of impairment in cognitive domains besides memory. One goal of the current study was to test this hypothesis in MS. A group of 55 MS patients were administered a variety of cognitive tasks and a self-report metamemory measure; patients significant others were also given a metamemory measure requiring them to rate patients memory abilities. Results indicated that patients metamemory reports were significantly (p < .05) correlated with verbal recall, attentional, and executive tasks. Significant other ratings of patients metamemory were correlated with verbal recall and attentional measures. Stepwise regression analyses including all relevant cognitive and demographic variables indicated that only education and Symbol Digit accounted for significant independent variance in patients current memory reports. Our results suggest: (1) subjective complaints of memory difficulties by MS patients reflect difficulty in cognitive domains besides memory, (2) MS patient self-reports of memory difficulty are at least as accurate as significant other reports, and (3) patients with more education are more accurate in their metamemory ratings. These findings have implications not only for a better understanding of metamemory in MS, but also for more effective treatment and rehabilitation of MS patients.

Walking stability during cell phone use in healthy adults.

The number of falls and/or accidental injuries associated with cellular phone use during walking is growing rapidly. Understanding the effects of concurrent cell phone use on human gait may help develop safety guidelines for pedestrians. It was shown previously that older adults had more pronounced dual-task interferences than younger adults when concurrent cognitive task required visual information processing. Thus, cell phone use might have greater impact on walking stability in older than in younger adults. This study examined gait stability and variability during a cell phone dialing task (phone) and two classic cognitive tasks, the Paced Auditory Serial Addition Test (PASAT) and Symbol Digit Modalities Test (SDMT). Nine older and seven younger healthy adults walked on a treadmill at four different conditions: walking only, PASAT, phone, and SDMT. We computed short-term local divergence exponent (LDE) of the trunk motion (local stability), dynamic margins of stability (MOS), step spatiotemporal measures, and kinematic variability. Older and younger adults had similar values of short-term LDE during all conditions, indicating that local stability was not affected by the dual-task. Compared to walking only, older and younger adults walked with significantly greater average mediolateral MOS during phone and SDMT conditions but significantly less ankle angle variability during all dual-tasks and less knee angle variability during PASAT. The current findings demonstrate that healthy adults may try to control foot placement and joint kinematics during cell phone use or another cognitive task with a visual component to ensure sufficient dynamic margins of stability and maintain local stability.

The clinical significance of neuropsychological changes following bilateral subthalamic nucleus deep brain stimulation for Parkinson's disease

Despite the clinical importance of the question, a number of methodological issues have limited firm conclusions regarding the cognitive safety of deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinsons disease (PD). Amongst these issues, studies have generally failed to consider the postoperative changes that occur within individual patients. This study utilized reliable change indices (RCIs) derived from a PD sample to determine the frequency of clinically significant postoperative decline on a battery of neuropsychological measures. This approach addresses measurement reliability, potential practice effects, and disease progression. The proportion of patients experiencing clinically significant postoperative decline on measures of list learning and verbal fluency was greater than expected based on disease progression; however, the majority of patients (55%) did not experience a significant decline in performance on any of the cognitive tests administered, and only one experienced decline on more than one test. Therefore, the statistically significant declines on measures of list learning and verbal fluency observed in the sample as a whole were the result of clinically significant declines experienced by a minority of participants.

Efficacy of tailored computer-based neurorehabilitation for improvement of movement initiation in Parkinson's disease

While Parkinsons disease (PD) is considered a motor disorder, motor signs of PD can be exacerbated by cognitive dysfunction. We evaluated the efficacy of a computer-based cognitive rehabilitation training program designed to improve motor-related executive function. Thirty people with PD and 21 controls participated in the 10-day training. Training consisted of a two-phase button press task. First, subjects produced an externally cued (EC) digit sequence, typing numbers displayed on the computer screen. Second, subjects were prompted to generate the same sequence in the absence of the number display (internally represented sequence, IR). Sequence length was automatically adjusted to maintain 87% correct performance. Participants were evaluated before and after training using a fixed version of the training task, and generalization of training was assessed using measures involving IR motor sequencing, switching and activities of daily living. PD participants were divided into two groups, those who showed impairment in IR motor sequence production prior to training (N=14) and those whose performance was similar to controls (N=16). Following training the impaired PD group showed significantly greater reduction in sequence initiation and completion time and in error rate for IR conditions compared to the unimpaired PD and control groups. All groups improved on Trails B-A, and pre-training Trails B was identified as a predictor of training-based improvement in IR sequence completion time and error rate. Our findings highlight the importance of neurorehabilitation tailored to the specific cognitive deficits of the PD patient.

Functional cooking skills and neuropsychological functioning in patients with stroke: An ecological validity study

Efforts to relate neuropsychological performance to real-world task functioning have predominantly yielded lackluster results, typically with neuropsychological performance accounting for modest amounts of variance in function. Nonetheless, the ecological validity of neuropsychological measures for predicting functional abilities remains a strong research interest and clinical necessity. This study relates neuropsychological performance to performance on a standardised cooking task (Rabideau Kitchen Evaluation – Revised; RKE-R) in persons with stroke. Results showed that while the composite score of mean neuropsychological performance had the largest association with meal preparation, several neuropsychological measures were significantly related to the RKE-R. Groups of left and right hemisphere stroke patients were not significantly different in terms of RKE-R performance. These results suggest that functional cooking task performance is related to intact cognitive abilities in delayed verbal memory, simple auditory attention, and visuospatial skills, as well as overall cognitive performance. Implications for neuropsychologists are discussed.

The contribution of trail making to the prediction of performance-based instrumental activities of daily living in Parkinson's disease without dementia

Performance on Part B of the Trail Making Test (TMT) contributes to the prediction of ability to complete instrumental activities of daily living (IADLs) in Parkinsons disease (PD). Although this suggests that cognitive flexibility is important in the everyday functioning of individuals with PD, this may not be the case as the TMT is multifactorial, involving motor speed, visual scanning, sequencing, and cognitive flexibility. The purpose of the current study was to determine which elements of the task contribute to the prediction of IADLs in a sample of 30 nondemented individuals with PD. Correlational analyses indicated strong relationships between a performance-based measure of IADLs and measures involving scanning, sequencing, and cognitive flexibility from the Delis–Kaplan Executive Function System (D-KEFS) TMT. Results from standard regressions indicated that measures of sequencing and level of depression but not scanning, cognitive flexibility, or demographic variables made a significant, independent contribution to the prediction of IADLs. These results suggest that the sequencing element of the TMT is paramount in the prediction of IADLs in PD.

Subjective Cognitive Complaints in Parkinson Disease Without Dementia: A Preliminary Study

Little is known about the subjective cognitive complaints of individuals with Parkinson disease (PD). Such complaints have become a topic of interest recently as they play a role in the diagnosis of neurocognitive disorders. The aim of this preliminary study was to determine whether a sample of nondemented individuals with PD reported significantly more difficulties with multiple elements of cognition than a control sample and to assess the relation between their ratings and demographics, motor symptom severity, neuropsychological test performance, and measures of depression and anxiety. Forty nondemented individuals with PD and 27 healthy individuals completed a questionnaire assessing everyday cognitive difficulties. Independent t tests indicated that individuals with PD reported significantly more cognitive complaints in general and in specific tasks involving complex attention, executive function, processing speed, and verbal fluency but not memory. Questionnaire ratings significantly correlated with measures assessing anxiety, verbal memory, processing speed, and verbal fluency. Results suggest that it is important to ask individuals with PD about cognitive complaints across several cognitive domains and also inquire about symptoms of anxiety, which may be related to their self-reported cognitive difficulties.

Perceived and performance-based executive dysfunction in Parkinson’s disease

Executive dysfunction is common in early stage Parkinson’s disease (PD). We evaluated the relationship between self- and informant-report measurement of real-world executive functions as well as performance-based neuropsychological measures in mildly cognitively impaired individuals with PD and healthy controls. The PD group reported more difficulty with initiation of complex tasks compared to caregiver ratings, and processing speed was a strong predictor of self-reported executive dysfunction for the PD group, followed by depression. Processing speed and semantic verbal fluency predicted informant-reported executive dysfunction in PD. These findings highlight the contribution of speeded processing for performance of everyday executive tasks in PD.

Cellular Telephone Dialing Influences Kinematic and Spatiotemporal Gait Parameters in Healthy Adults.

ABSTRACT Gait speed is typically reduced when individuals simultaneously perform other tasks. However, the impact of dual tasking on kinetic and kinematic gait parameters is unclear because these vary with gait speed. The objective of this study was to identify whether dual tasking impacts gait in healthy adults when speed is constant. Twenty-two healthy adults dialed a cell phone during treadmill walking at a self-selected speed while kinetic, kinematic, and spatial parameters were recorded. Results indicated that dual tasking did not impact phone dialing speed, but increased stride width, peak knee flexion during stance, and peak plantarflexion, and decreased knee and ankle range of motion. Dual tasking appears to influence kinematic gait variables in a manner consistent with promotion of stability.

The ecological validity of clinical tests of visuospatial function in community-dwelling older adults.

Little is known about the relation between measures of visuospatial function and daily functioning in community-dwelling older adults. The current study addresses this gap in the literature. Forty individuals with mean (SD) age and education of 78.4 (7.5) and 11.9 (2.6) years, respectively, completed a battery of neuropsychological measures including traditional tests of visuospatial function, a test of visuospatial function with verisimilitude, and performance-based measures of global daily functioning and visuospatial daily functioning. Unlike previous studies, statistical analyses directly evaluated the magnitude of the correlations between cognitive tests and daily functioning. Results indicated that all visuospatial measures significantly correlated with both measures of daily functioning (rs = .34-.59). Although the measure designed with verisimilitude was not significantly better than the traditional visuospatial measures at predicting daily functioning, it did account for significant variance beyond that accounted for by the other tests, supporting its incremental validity.