Lori J. P. Altmann

High-Level Language Production in Parkinson's Disease: A Review

This paper discusses impairments of high-level, complex language production in Parkinsons disease (PD), defined as sentence and discourse production, and situates these impairments within the framework of current psycholinguistic theories of language production. The paper comprises three major sections, an overview of the effects of PD on the brain and cognition, a review of the literature on language production in PD, and a discussion of the stages of the language production process that are impaired in PD. Overall, the literature converges on a few common characteristics of language production in PD: reduced information content, impaired grammaticality, disrupted fluency, and reduced syntactic complexity. Many studies also document the strong impact of differences in cognitive ability on language production. Based on the data, PD affects all stages of language production including conceptualization and functional and positional processing. Furthermore, impairments at all stages appear to be exacerbated by impairments in cognitive abilities.

Dual-task effects of spontaneous speech and executive function on gait in aging: Exaggerated effects in slow walkers

This study compared the effects of spontaneous speech and executive function on gait and investigated the effects of single-task gait speed on dual-task costs. Twenty-one older adults (74.7 years, SD 5.9) and 23 younger adults (22 years, SD 1.2) walked for 60s while performing an auditory Stroop task and a spontaneous speech task; they also performed each task in isolation. Walking while talking significantly reduced gait speed in both groups; however, only older adults experienced significant cognitive-motor interference during the Stroop task. Stride duration variability and gait symmetry were also affected by the speech task in older but not younger adults. Dual-task costs on gait speed were greater in slow-walking older adults than fast walkers. These results demonstrate that spontaneous speech is a highly demanding task that has a profound impact on gait in older adults, especially those with gait speed <1 m/s.

Interference Between Cognition, Double-Limb Support, and Swing During Gait in Community-Dwelling Individuals Poststroke

Background. Dual tasking can interfere with activity after stroke. Objective. The authors examined the interactions between 3 different cognitive tasks and the swing and double-limb support (DLS) components of the gait cycle in community-dwelling individuals poststroke. Methods. Acquisition of cognitive and gait data were synchronized to study the cognitive—motor interference effects during the different phases of the gait cycle. Participants performed 3 different cognitive tasks in isolation and in combination with walking as well as a single walking task. Tasks were performed continuously for 3 minutes, generating 131 ± 39 gait cycles per person for analysis for each walking trial. Data were analyzed for 8 participants 7.6 ± 4.2 months poststroke. Results. A significant increase was found in the proportion of the gait cycle spent in DLS in dual-task walking because of an increased duration of the DLS phase associated with paretic weight acceptance. There was a significant dual-task effect on nonparetic swing duration: participants reduced the amount of time in paretic single-limb stance in the 3 dual-task conditions. Temporal asymmetry of gait did not increase significantly under dual-task conditions. Reaction times were not affected by whether the stimuli were present during the swing or DLS phase of the gait cycle. Conclusions. The findings from this pilot study provide evidence that cognitive—motor interference during gait may be influenced by the phase of the gait cycle, especially DLS involving paretic weight acceptance, which may affect community ambulators with hemiparetic stroke.

Can exercise improve language and cognition in Parkinson's disease? A case report

Parkinsons disease is commonly accompanied by cognitive issues that limit participation in activities of daily living. Unfortunately, most current treatment paradigms and pharmacotherapeutics fail to address the cognitive impairment demonstrated in this population. Mounting evidence in healthy older adults suggests that aerobic exercise may improve cognitive function. This article describes a patient with Parkinsons disease prescribed 8 weeks of aerobic exercise. Despite very high performance at baseline, the participant improved on several cognitive measures post exercise. The results of this investigation mimic the research in healthy older adults. We therefore suggest that future large scale randomized trials are warranted to evaluate the efficacy of aerobic exercise for ameliorating declines in cognitive performance in persons with PD.

Sentence comprehension in young adults with developmental dyslexia

This study investigated the effects of syntactic complexity on written sentence comprehension in compensated adults with dyslexia. Because working memory (WM) plays a key role in processing complex sentences, and individuals with dyslexia often demonstrate persistent deficits in WM, we hypothesized that individuals with dyslexia would perform more poorly on tasks designed to assess the comprehension of syntactic structures that are especially taxing on WM (e.g., passives, sentences with relative clauses). Compared to their nondyslexic peers, individuals with dyslexia were significantly less accurate and marginally slower on passive sentences. For sentences containing relative clauses, the dyslexic group was also less accurate but did not differ in response times. Covarying WM and word reading in both analyses eliminated group differences showing that syntactic deficits in adults with dyslexia are constrained by both WM and word-reading ability. These findings support previous research showing that syntactic processing deficits are characteristic of dyslexia, even among high-achieving students.

Effects of Semantic Impairment on Language Use in Alzheimer's Disease

Many studies present apparently conflicting results and conclusions about the effects of Alzheimers disease (AD) on language use. This review attempts to reconcile these apparently conflicting results regarding the language impairments in AD by discussing how the slow deterioration of the semantic system at the feature level interacts with the task demands of tests used to evaluate performance. In particular, performance is impaired on tasks that require relatively complete, elaborate semantic representations but is preserved when the task requires only partial semantic representations consisting largely of shared features. The variety of language impairments reported in complex, multiword tasks are likely attributable to a combination of the deterioration of semantic representations and reduced working memory resources. The few available treatment studies for language impairments in AD suggest that treatments designed for adults with other language impairments, such as aphasia, may also be effective in AD.

Associations Between Cognitive and Gait Performance During Single- and Dual-Task Walking in People With Parkinson Disease

Background Cognitive impairments in Parkinson disease (PD) manifest as deficits in speed of processing, working memory, and executive function and attention abilities. The gait impairment in PD is well documented to include reduced speed, shortened step lengths, and increased step-to-step variability. However, there is a paucity of research examining the relationship between overground walking and cognitive performance in people with PD. Objective This study sought to examine the relationship between both the mean and variability of gait spatiotemporal parameters and cognitive performance across a broad range of cognitive domains. Design A cross-sectional design was used. Methods Thirty-five participants with no dementia and diagnosed with idiopathic PD completed a battery of 12 cognitive tests that yielded 3 orthogonal factors: processing speed, working memory, and executive function and attention. Participants completed 10 trials of overground walking (single-task walking) and 5 trials of overground walking while counting backward by 3s (dual-task walking). Results All gait measures were impaired by the dual task. Cognitive processing speed correlated with stride length and walking speed. Executive function correlated with step width variability. There were no significant associations with working memory. Regression models relating speed of processing to gait spatiotemporal variables revealed that including dual-task costs in the model significantly improved the fit of the model. Limitations Participants with PD were tested only in the on-medication state. Conclusions Different characteristics of gait are related to distinct types of cognitive processing, which may be differentially affected by dual-task walking due to the pathology of PD.

Changes in aphasic discourse after contrasting treatments for anomia

Background: Discourse analysis is a key element in determining treatment effects. However, it is extremely labour intensive, requiring in‐depth knowledge of linguistics and aphasiology; thus, it is often neglected in the analysis of treatment outcomes. A clinically practical method of discourse analysis would be beneficial for evaluation and determination of treatment efficacy. Aims: The current study investigates changes in discourse content following contrasting treatments for anomia using grammatical analysis. In addition, we pilot the use of a new information measure. Methods & Procedures: We compare discourse changes after a gestural + verbaltreatment and a semantic‐phonologic treatment for nouns and verbs on two groups of individuals with aphasia. Analyses compared discourse samples from 14 participants taken at baseline, post‐phase 1, and post‐phase 2. In addition to traditional measures such as number of nouns, verbs, and sentence types, a new measure of information is introduced, the Utterance with New Information (UNI). The UNI is designed to assess content in non‐propositional, impaired speech in open‐ended discourse. Outcomes & Results: Noun production increased in participants of both treatments, whereas grammatical sentences increased only in participants of the semantic‐phonologic treatment. Production of UNIs increased in participants of both treatments as well as over time. Conclusions: This study demonstrates that a few easily counted measures of discourse production can provide clinically useful information for the clinician. Moreover, these findings suggest discourse analysis is a viable method of determining treatment outcomes especially given that improving discourse is the ultimate goal of all aphasia treatments.

Discourse coherence and cognition after stroke: A dual task study

UNLABELLED Several researchers have suggested that the maintenance of global coherence (topic maintenance) and local coherence (maintenance between utterances) in discourse requires cognitive resources. This study directly tests this hypothesis by examining the relationship between cognitive variables and coherence in narrative discourse produced by mobility-impaired stroke survivors under single (talking) and dual (talking and walking) task conditions. Although there were no effects of the dual task on coherence, global coherence was significantly disrupted regardless of the single or dual task condition. Moreover, global coherence strongly correlated with cognitive function measures, whereas local coherence did not. Findings are consistent with two interpretations: (1) that global and local coherence may be subserved by different cognitive processes or (2) that maintaining global coherence is a more difficult task and thus will show effects of cognitive impairment before local coherence is impaired. These are both testable hypotheses for future research. LEARNING OUTCOMES After reading the manuscript, the reader will be able to: (1) understand and differentiate between local and global measures of coherence; (2) discuss the effects of a dual task, walking and talking, on global coherence in a gait-impaired group of stroke survivors; (3) understand why the maintenance of global coherence in discourse might be more cognitively demanding than the maintenance of local coherence.

Sentence Production in Parkinson Disease: Effects of Conceptual and Task Complexity.

Experimental studies of sentence production in Parkinson disease (PD) are rare. This study examined the relationship between cognitive abilities and performance on two sentence production tasks, sentence repetition, and sentence generation, in which complexity was manipulated. Thirty-eight older adults aged 60 to 85, half with PD, completed the two language tasks plus a cognitive battery. Participants with PD performed more poorly in the repetition task overall, especially in fluency, but differences were no longer significant once cognitive ability was controlled. In contrast, on the sentence generation task the PD group was significantly impaired on all language dimensions and overall performance. Although cognitive ability accounted for significant variance in all measures of sentence generation, the PD group remained significantly impaired when these factors were controlled. These findings suggest that, although language production is influenced by cognitive abilities, it can be significantly impaired in PD over and above the effects of differences in cognitive abilities.