Elena Herrera

Cognitive impairment in Parkinson's disease without dementia.

Some degree of cognitive impairment appears frequently in Parkinsons disease (PD) patients, even at the onset of the disease. However, due to the heterogeneity of the patients and the lack of standardized assessment batteries, it remains unclear which capacities are primarily affected by this disease. Fifty PD patients were assessed with 15 tests including executive functions, attention, temporal and spatial orientation, memory, and language tasks. Their results were compared with those of 42 age‐ and education‐matched healthy seniors. Semantic fluency, along with visual search appeared to be the most discriminant tasks, followed by temporal orientation and face naming, as well as action naming and immediate recall. PD patients studied showed an impairment of frontal‐ to posterior‐dependent capacities. Executive functions, attention, and recall tasks appeared to be significantly impaired in the patients. Nevertheless, significantly poor scores in tasks like action and face naming, as well as semantic fluency, also reveal a mainly semantic deficit.

The effect of motion content in action naming by Parkinson's disease patients.

INTRODUCTION The verb-specific impairment present in patients with motion-related neurological diseases has been argued to support the hypothesis that the processing of words referring to motion depends on neural activity in regions involved in motor planning and execution. We presented a group of Parkinsons disease (PD) patients with an action-naming task in order to test whether the prevalence of motion-related semantic content in different verbs influences their accuracy. METHODS Forty-nine PD patients and 19 healthy seniors participated in the study. All of PD participants underwent a neurological and neuropsychological assessment to rule out dementia. Subjective ratings of the motion content level of 100 verbs were obtained from 14 young voluntaries. Then, pictures corresponding to two subsets of 25 verbs with significantly different degrees of motor component were selected to be used in an action-naming task. Stimuli lists were matched on visual and psycholinguistic characteristics. RESULTS ANOVA analysis reveals differences between groups. PD patients obtained poor results in response to pictures with high motor content compared to those with low motor association. Nevertheless, this effect did not appear on the control group. The general linear mixed model analytic approach was applied to explore the influence of the degree of motion-related semantic content of each verb in the accuracy scores of the participants. The performance of PD patients appeared to be negatively affected by the level of motion-related semantic content associated to each verb. CONCLUSIONS Our results provide compelling evidence of the relevance of brain areas related to planning and execution of movements in the retrieval of motion-related semantic content.

Action naming in Parkinson's disease patients on/off dopamine.

Growing evidence supports the notion that the same brain areas involved in planning and execution of movements are also involved in verb processing. Recent studies have pointed out the existence of verb impairment in patients with Parkinsons disease (PD), a neurodegenerative disorder typically characterized by motor disturbance related to dopamine deficiency in the nigrostriatal system. The aim of this study was to test the influence of dopaminergic treatment in a group of non-demented PD patients on the performance of action naming. The action pictures belonged to two categories: pictures with high and low degree of motor content. A group of 20 PD patients without dementia and 15 controls performed the task. PD patients were assessed twice, on and off medication, controls only once. A repeated measures ANOVA was carried out on the reaction times. The results showed a main effect of group and a significant interaction between group×motor content when comparing the three groups. When the comparison was made only on the PD groups (on vs. off medication) the interaction group×motor content was also significant, indicating that PD patients off medication had longer reaction times for pictures with a high degree of motor content compared to PD patients on medication. These results suggest a selective deficit in naming pictures associated with high motor content in PD patients without dopamine medication. This effect could be due to the relations between brain motor areas and verb processing associated with dopamine depletion.

Emotion recognition impairment in Parkinson's disease patients without dementia

PURPOSE Previous research has shown dementia and mild cognitive impairment to be present in some Parkinsons disease (PD) patients. Nevertheless, it is still not clear whether PD patients are also impaired on facial emotion recognition, nor it is whether this possible deficit is independent other cognitive impairment. The aim of this study is to assess the presence of emotion recognition deficits in a sample of PD patients with normal cognitive abilities, evaluated with several cognitive tasks widely used to detect cognitive impairment in this patient group. METHOD 40 non-demented (MMSE scores>25) PD patients and 19 healthy older adults matched on demographic characteristics took part in the study. All of them were evaluated with a neuropsychological battery including tests aimed to assess the cognitive domains mainly affected by PD, as well as a facial emotion recognition task. RESULTS t-test analysis showed significant differences between PD and control groups in 6 cognitive tasks which were introduced in a sequential logistic regression analysis. The results confirmed the existence of a facial emotion recognition deficit in PD patients after controlling for demographic and cognitive characteristics of the participants. CONCLUSION Although none of the PD patients fulfilled criteria for dementia, many of them appeared to present deficits on recognition of facial emotions. This task should therefore be incorporated into future research to study the full range of early cognitive dysfunctions and non-motor symptoms presents in PD patients, and inclusion of this task in assessment protocols should be considered.

Verbal fluency in Parkinson's disease patients on/off dopamine medication.

INTRODUCTION Parkinsons disease (PD) is associated with dopamine depletion in the fronto-striatal network which affects some language aspects such as verb processing. Some experiments have demonstrated that dopamine deficiency plays a role in the normal functioning of the lexico-semantic system. As a result, the verbal fluency task could be a useful tool to assess the function of the semantic system, by examining both the number of words generated and the frequency of use of those words. OBJECTIVE The aim of this study was to find out how dopamine affects the performance of PD patients using a verbal fluency task, focussing on action-word fluency. METHOD A group of 20 PD patients and 20 controls participated in the study. Participants were assessed with four different verbal fluency tasks: phonological, semantic (animal and supermarket words) and action fluency. PD patients were tested twice (on/off medication) and controls only once. RESULTS For the number of words, there were significant differences between PD patients on and off medication in the phonological and action fluency tasks. Compared to controls, PD off medication produced significantly fewer words in phonological, and actions. Regarding frequency, differences were found between PD patients off medication and controls for the action-word category. DISCUSSION Our data showed a specific deficit in PD patients off medication in categories mainly depending on frontal lobe function (phonological and actions) while these differences were restored with dopamine treatment. Moreover, PD patients off medication produced higher frequency verbs than controls, suggesting that dopamine affects the normal functioning within the lexico-semantic network of verbs.

Semantic disturbance for verbs in Parkinson's disease patients off medication

Abstract Word-association tasks are considered useful tools to assess the normal functioning of the lexico-semantic system in healthy people and patients suffering from neurological disorders. Parkinsons Disease (PD) patients usually present some language dysfunction related to the functioning of the semantic system as a consequence of dopamine depletion. The aim of this study was to check if there were differences in the strength of association of the words generated by a group of non-demented PD patients on and off dopamine medication using a word-association task. In the study, 20 PD patients and 20 healthy-matched controls performed a word association task consisting of 10 nouns and 10 verbs matched by psycholinguistic variables. The participants were asked to generate the first word that came to mind given a specific single target. The results revealed that PD patients off medication said words less associated with the target compared with when they were on medication. Interestingly, comparisons between PD off patients and healthy controls revealed statistical differences only in response to verbs, while differences between PD on and controls were not found. Regarding nouns, we did not find any difference between PD off or PD on and healthy controls. This experiment adds more evidence to the assumption that the lexico-semantic system is disrupted in the absence of dopamine, resulting in poor spreading activation among associative words.

A third-person perspective on co-speech action gestures in Parkinson's disease

A combination of impaired motor and cognitive function in Parkinsons disease (PD) can impact on language and communication, with patients exhibiting a particular difficulty processing action verbs. Co-speech gestures embody a link between action and language and contribute significantly to communication in healthy people. Here, we investigated how co-speech gestures depicting actions are affected in PD, in particular with respect to the visual perspective—or the viewpoint – they depict. Gestures are closely related to mental imagery and motor simulations, but people with PD may be impaired in the way they simulate actions from a first-person perspective and may compensate for this by relying more on third-person visual features. We analysed the action-depicting gestures produced by mild-moderate PD patients and age-matched controls on an action description task and examined the relationship between gesture viewpoint, action naming, and performance on an action observation task (weight judgement). Healthy controls produced the majority of their action gestures from a first-person perspective, whereas PD patients produced a greater proportion of gestures produced from a third-person perspective. We propose that this reflects a compensatory reliance on third-person visual features in the simulation of actions in PD. Performance was also impaired in action naming and weight judgement, although this was unrelated to gesture viewpoint. Our findings provide a more comprehensive understanding of how action-language impairments in PD impact on action communication, on the cognitive underpinnings of this impairment, as well as elucidating the role of action simulation in gesture production.