Keith M. Robinson

Language comprehension profiles in Alzheimer's disease, multi-infarct dementia, and frontotemporal degeneration.

We assessed language functioning in 116 age-, education-, and severity-matched patients with the clinical diagnosis of Alzheimers disease (AD), multi-infarct dementia (MID) due to small-vessel ischemic disease, or a frontotemporal form of degeneration (FD). Assessments of comprehension revealed that patients with AD are significantly impaired in their judgments of single word and picture meaning, whereas patients with FD had sentence comprehension difficulty due to impaired processing of grammatical phrase structure. Patients with MID did not differ from control subjects in their comprehension performance. Traditional aphasiologic measures did not distinguish between AD, MID, and FD. Selective patterns of comprehension difficulty in patients with different forms of dementia emphasize that language deficits cannot be explained entirely by the compromised memory associated with a progressive neurodegenerative illness. NEUROLOGY 1996;47: 183-189

Working Memory Impairments in Multiple Sclerosis: Evidence From a Dual-Task Paradigm

The aim of this study was to investigate working memory in multiple sclerosis (MS) patients. To test the hypothesis that the central executive system (CES) of working memory is impaired, 36 MS patients were administered a dual-task paradigm in which a judgment of line orientation measure was performed concurrently with finger tapping, humming a melody, or reciting the alphabet. MS patients exhibited a significantly greater decrement in performance than controls during the more demanding dual-task conditions (concurrent humming or alphabet recitation) as compared with the single-task condition. Dual-task performance in MS patients correlated with performance on the Paced Auditory Serial Addition Test but not with other cognitive or clinical measures. The authors conclude that MS patients have a working memory deficit reflecting an impaired central executive system. Moreover, impairments in speed of information processing in MS patients are associated with this CES deficit. Memory dysfunction is the most common cognitive impairment observed in patients with multiple sclerosis (MS). A long-term memory deficit in these patients is well documented (Grafman, Rao, & Litvan, 1990), but most early studies of MS patients have concluded that short-term memory (STM) is intact. Support for this claim was derived from the observation of a normal digit span, as well as an intact recency effect on supraspan list learning, measures commonly used to assess STM (Caine, Bamford, Schiffer, Shoulson, & Levy, 1986; Rao, Hammeke, McQuillen, Khatri, & Lloyd, 1984). Although most studies continue to focus on the long-term memory impairments in MS patients (Rao, Leo, & Aubin-Faubert, 1989), evidence is accumulating that STM deficits may also exist (Grigsby, Ayarbe, Kravcism, & Busenbark, 1994; Rao et al., 1993). However, the nature of these deficits remain unclear. The purpose of this study was to further investigate STM processing in MS patients. Several experimental tasks have been useful for identifying impairment in various aspects of STM in MS patients. One experimental measure, the Brown-Peterson task (Peterson & Peterson, 1959), measures consolidation of information in STM and the effect of interference on temporarily stored information. With this task, two groups of investigators (Beatty, Goodkin, Monson, Beatty, & Hertsgaard, 1988; Grant,

Category-specific difficulty naming with verbs in Alzheimer's disease

We studied 20 patients with Alzheimers disease (AD) on a picture-naming task consisting of frequency-matched pairs of nouns and verbs that were homophonic and homographic (e.g., paint). Intragroup comparisons revealed that verb naming is significantly more difficult for patients with AD than noun naming. An error analysis demonstrated that patients with AD produce significantly more semantic and descriptive errors for verbs than nouns. We correlated verb naming and noun naming with measures of grammatical comprehension, lexical retrieval, and visuoperceptual processing, but there were no selective effects for verbs compared with nouns. Differences in the mental representation of concepts underlying verbs and nouns may account, in part, for the relative difficulty naming with verbs in AD. NEUROLOGY 1996;47: 178-182

Falling in Parkinson disease: identifying and prioritizing risk factors in recurrent fallers.

Dennison AC, Noorigian JV, Robinson KM, Fisman DN, Cianci HJ, Moberg P, Bunting-Perry L, Martine R, Duda J, Stern MB: Falling in Parkinson disease: identifying and prioritizing risk factors in recurrent fallers. Am J Phys Med Rehabil 2007;86:621–632. Objectives:To identify falling risk factors in a study population of recurrent fallers compared with nonfallers who have Parkinson disease, and to prioritize falling risk factors in this patient population to target them for modification. Design:Twenty-three recurrent fallers and 25 nonfallers who have Parkinson disease were recruited, and they participated in a comprehensive assessment probing for the presence of falling risk factors. To identify falling risk factors, a group comparative design was used to compare recurrent fallers and nonfallers across an array of variables. To prioritize those risk factors, modeling using recursive partitioning was performed, entering into the model falling, risk factors identified in this and other studies that were considered potentially modifiable. Results:A specific profile of variables distinguished recurrent fallers who have Parkinson disease in our study population: higher disease severity, higher level of motor impairment, higher level of disability, impaired leg agility or lower-limb coordination, impaired ability to arise from a chair or compromised proximal lower-limb motor control, impaired ambulation, impaired motor planning of the hands and feet, impaired dynamic balance as measured by ability to walk in tandem, and fear of falling. Recursive partitioning prioritized three risk factors: impaired ambulation, impaired lower-limb motor planning, and orthostasis. Conclusions:In this study, an idiosyncratic falling risk factor profile was demonstrated among our subjects who have Parkinson disease. Three variables were prioritized for potential modification: impaired ambulation, impaired lower-limb motor planning, and orthostasis.

Constraints on the cerebral basis for semantic processing from neuroimaging studies of Alzheimer’s disease

OBJECTIVE Functional activation studies of semantic processing in healthy adults have yielded conflicting results. The purpose was to evaluate the relative role of the brain regions implicated in semantic processing with converging evidence from imaging studies of patients with impaired semantic processing. METHODS Semantic memory was assessed in patients with Alzheimer’s disease using two measures, and these performance patterns were related to profiles of reduced cerebral functioning obtained with high resolution single photon emission computed tomography (SPECT). Patients with frontotemporal degeneration were similarly evaluated as a control group. RESULTS Reduced relative cerebral perfusion was seen in parietal and posterior temporal brain regions of patients with Alzheimer’s disease but not patients with frontotemporal degeneration. Impairments on semantically guided category membership decision tasks were also seen in patients with Alzheimer’s disease but not those with frontotemporal degeneration. Performance on the semantic measures correlated with relative cerebral perfusion in inferior parietal and superior temporal regions of the left hemisphere only in Alzheimer’s disease. Relative perfusion was significantly lower in these regions in patients with Alzheimer’s disease with semantic difficulty compared with patients with Alzheimer’s disease with relatively preserved semantic processing. CONCLUSION These findings provide converging evidence to support the contribution of superior temporal and inferior parietal regions of the left hemisphere to semantic processing.

Semantic memory in Alzheimer's disease: representativeness, ontologic category, and material.

Alzheimers disease (AD) patients with semantic memory difficulty and AD patients with relatively preserved semantic memory named pictures and judged the category membership of words and pictures of natural kinds and manufactured artifacts that varied in their representativeness. Only semantically impaired patients were insensitive to representativeness in their category judgments. AD subgroup judgments did not differ for natural kinds compared to manufactured artifacts nor for words compared to pictures. AD subgroup differences could not be explained by dementia severity, memory, reading, and visuoperception. The similarity process for relating coordinate members of a taxonomic category contributes to the normal appreciation of word and picture meaning, and this process is compromised in AD patients with semantic difficulty.

The Effect of Post-injury Depression on Return to Pre-injury Function: a Prospective Cohort Study

BACKGROUND Millions of people seek emergency department (ED) care for injuries each year, the majority for minor injuries. Little is known about the effect of psychiatric co-morbid disorders that emerge after minor injury on functional recovery. This study examined the effect of post-injury depression on return to pre-injury levels of function. METHOD This was a longitudinal cohort study with follow-up at 3, 6 and 12 months post-injury: 275 adults were randomly selected from those presenting to the ED with minor injury; 248 were retained over the post-injury year. Function was measured with the Functional Status Questionnaire (FSQ). Psychiatric disorders were diagnosed using the Structured Clinical Interview for DSM-IV-TR disorders (SCID). RESULTS During the post-injury year, 18.1% [95% confidence interval (CI) 13.3-22.9] were diagnosed with depression. Adjusting for clinical and demographic covariates, the depressed group was less likely to return to pre-injury levels of activities of daily living [odds ratio (OR) 8.37, 95% CI 3.78-18.53] and instrumental activities of daily living (OR 3.25, 95% CI 1.44-7.31), less likely to return to pre-injury work status (OR 2.37, 95% CI 1.04-5.38), and more likely to spend days in bed because of health (OR 2.41, 95% CI 1.15-5.07). CONCLUSIONS Depression was the most frequent psychiatric diagnosis in the year after minor injury requiring emergency care. Individuals with depression did not return to pre-injury levels of function during the post-injury year.

Serial position and temporal cue effects in multiple sclerosis: Two subtypes of defective memory mechanisms

Neurocognitive studies of multiple sclerosis (MS) have identified a robust long-term memory deficit. We hypothesized that this is due in part to the limited representation and use of serial order information. MS patients and controls were studied with a supraspan list learning procedure with post-encoding retrieval and recognition trials. MS patients demonstrated post-encoding negative recency with normal recognition, and word order recall was impaired. These findings appear to be in part to difficulty using temporal order cues in long-term memory. Two dissociable memory deficits were identified, suggesting that there are at least two neurocognitive mechanisms underlying memory impairment in MS.

Rehabilitation applications in caring for patients with Pick’s disease and frontotemporal dementias

The basic principles of rehabilitation philosophy relevant to the care of patients with neurodegenerative diseases, specifically Pick’s disease and frontotemporal dementias, are briefly defined. These principles are illustrated by the case study of a patient with a clinical diagnosis of Pick’s disease.

Sentence comprehension in multiple sclerosis

Introduction ‐ Explanations of sentence processing difficulty in aphasia have implicated slowed information processing speed. We tested this hypothesis by evaluating sentence comprehension in multiple sclerosis (MS), and relating comprehension performance to measures of information processing speed. Material & methods ‐ Twenty right‐handed, high school‐educated, non‐demented, native English speakers with clinically definite MS and 16 age‐ and education‐matched control subjects were examined on 3 different sentence comprehension measures that stress grammatical appreciation. Performance was related to quantitative assessments of mental information processing speed. Results ‐ Group‐wide analyses demonstrated a trend toward sentence comprehension difficulty in MS. Analyses of individual patient profiles identified a subgroup of MS patients who were consistently impaired to a significant extent across all sentence comprehension tasks. Their sentence comprehension difficulty was associated with selectively compromised mental information processing speed. Conclusion ‐ Sentence comprehension difficulty in MS is associated with slowed information processing speed. This finding supports the claim that information processing speed contributes to sentence processing.