C D Marsden

Cognitive function in Parkinson's disease: from description to theory.

From the large body of empirical evidence on cognitive function in Parkinsons disease, a number of attempts have been made to describe the characteristics of the deficits and the conditions under which they are observed. This review considers descriptions limited to specific domains of cognition such as visuospatial function, memory and frontal function, and more general descriptions relating to set-shifting, sequencing, temporal ordering and recency discrimination, the locus of cognitive control and bradyphrenia. Later in the paper an attempt is made to provide some theoretical framework for the various descriptions. Two theories are discussed representing contrasting, but complementary approaches. The first is a psychological theory in which the concept of depleted processing resources is suggested as a possible mechanism to explain the observable deficits. The second is a neurobiological model that attempts to integrate information from diverse sources to provide a model for the neuroanatomical and neurochemical substrate that may underlie some of the behavioural deficits.

Subcortical dementia: the neuropsychological evidence

Commentaires a propos des criteres neuropsychologiques de la demence «subcorticale», des similarites ou differences avec les demences de type cortical en se fondant sur les troubles du comportement, langage, memoire et fonctions visuospatiales

Depression and disability in Parkinson's disease: a follow-up of 132 cases

Patients with Parkinsons disease, 132 in number, were followed up after approximately one year, and measures of depression and disability re-administered. Depression was common on both occasions, and was characterized by dysphoria, pessimism and somatic symptoms, but not guilt or self-blame. Depression and disability were associated on both occasions. The relationship between changes in disability and depression across time was complex. In trying to understand changes in depression, the absolute change in disability may be less important than the relative change and rate of change. The results were discussed in relation to findings from other disease groups, and the implications for the clinical management of depression in Parkinsons disease.

A comparative study of simple and choice reaction time in Parkinson's, Huntington's and cerebellar disease.

The aim of the study was to compare the quantitative and qualitative similarities and differences in the performance of patients with Parkinsons disease, Huntingtons disease and cerebellar disease on a number of reaction time tasks. Simple reaction time (SRT), uncued and fully cued four choice (CRT) tasks were performed by eight patients with Parkinsons disease after withdrawal of dopaminergic medication for an average of 14.4 hours; by seven non-demented patients with Huntingtons disease and by eight patients with cerebellar disease. An S1 (warning signal/precue)-S2 (imperative stimulus) paradigm was used in all tasks, with the S1-S2 interval randomly varying between 0, 200, 800, 1600 and 3200 ms across trials. The patients with Huntingtons disease had a significantly longer SRT than those with Parkinsons disease. None of the other group differences in uncued and unwarned SRT and CRT was significant. For the patients with Parkinsons disease and those with cerebellar disease, unwarned SRT was faster than uncued and unwarned CRT. For the patients with Huntingtons disease, this CRT/SRT difference was not significant. A warning signal before the imperative stimulus resulted in a reduction of reaction time in all three groups. Advance information provided by S1 about the response that would be required by S2 was used by patients in all three groups, evident from reaction times in the fully cued CRT task being faster than those in the uncued CRT condition. Patients with cerebellar disease had slower movement times in the SRT and CRT conditions compared with the patients with Parkinsons disease and Huntingtons disease, whose times did not differ. In one SRT condition, when the absence of a warning signal was predictable, patients with cerebellar disease, and to a lesser extent those with Huntingtons disease, were able to maintain a general motor readiness before the imperative stimulus. This was not the case for the patients with Parkinsons disease who seemed more dependent on the presence of a warning signal to reduce their reaction time. With a few exceptions, the pattern of results of the three groups were qualitatively similar. It may be concluded that similar reaction time deficits are found in Parkinsons disease, in patients with other disorders of the basal ganglia (Huntingtons disease), as well as those with a disease sparing the basal ganglia (cerebellar disease). The non-specific slowness observed at the behavioural level may, however, have diverse central mechanisms.

Effect of practice on performance of a skilled motor task in patients with Parkinson's disease.

Parkinsons disease leads to a breakdown in the execution of highly practised, skilled movements such as walking and handwriting. The improved execution of skilled movements with practice can be understood as a process of schema learning, the determining of the relevant parameters of the specific movement. The ability of patients with Parkinsons disease and age matched normal control subjects to improve their performance, with practice, on a skilled motor task, doing up buttons, was assessed. The task was assessed on its own and with simultaneous foot tapping. Both groups showed an initial improvement in the task on its own and deterioration in performance when buttoning with foot tapping. The amount of interference, however, decreased with practice, particularly in the patients with a 2 Hz tapping rate. The results suggest that patients with Parkinsons disease are capable of schema learning but require more practice than control subjects to achieve comparable levels of performance. This may be a reflection of the fundamental motor dysfunction of the disease rather than a specific learning deficit.

The execution of bimanual movements in patients with Parkinson's, Huntington's and cerebellar disease.

Patients with Parkinsons disease have difficulty in performing two different tasks simultaneously. The present study tested whether this deficit was specific to the disease or was found in other patient groups. An identical pattern of performance was shown by a group of patients with cerebellar disease and, to a lesser extent, by a group of patients with Huntingtons disease. Further research should focus on clarifying the nature of the deficits and the reasons for the similar performances in the various patient groups.

The effect of withdrawal of dopaminergic medication on simple and choice reaction time and the use of advance information in Parkinson's disease.

Eight patients with Parkinsons disease performed simple reaction time (SRT), uncued, partially and fully cued four choice (CRT) tasks. They were tested on two occasions; on their normal dose of dopaminergic medication and following withdrawal of such medication for an average of 14.4 hours. Disability as rated on the Webster scale was greater in the drug reduced state. Although RTs were generally slower when tested in the drug reduced state than when on medication, few differences emerged. Withdrawal of dopaminergic medication had no effect on unwarned SRT and unwarned and uncued CRT performance. Both on and off medication, the patients benefited from a warning signal presented before the imperative stimulus. In both medication states, the speeding up of RT was greatest with a warning signal presented 200 ms before S2. When the imperative stimulus was unwarned, the temporal predictability of its occurrence speeded RT more when on medication than when off. Advance movement parameter information was used by patients to pre-programme responses both on and off medication. In both medication states, the fully cued CRT was the same as SRT only with the 3200 ms S1-S2 interval. Medication state had no effect on movement time or the number of errors. It is suggested that slowness in motor readiness and motor programming may not be specific to striatal dopamine deficiency but rather a nonspecific concomitant of brain damage.

EMG BIOFEEDBACK TREATMENT OF TORTICOLLIS - A CONTROLLED OUTCOME STUDY

Successful treatment of torticollis with electromyographic (EMG) biofeedback has been reported in a number of single case and single group studies. The present investigation represents the first controlled outcome study. Twelve torticollis patients were randomly assigned to EMG biofeedback or relaxation training and graded neck exercises (RGP). The procedure involved three sessions of baseline assessment, 15 sessions of EMG BF or RGP, 6 sessions of EMG BF or RGP plus home-management, 6 sessions of home-management alone, and follow-up 3 months after the end of treatment. A variety of outcome measures were used including physiological (EMG from the two sternocleidomastoid muscles, skin conductance level), behavioral (angle of head deviation, range of movement of the head), and self-report (depression, functional disability, body concept), therapist and “significant other” reports and independent observer assessment of videos. In both groups, neck muscle activity was reduced from pre- to posttreatment. This reduction was greater in the EMG biofeedback group. There was evidence of feedback-specific neck muscle relaxation in the EMG biofeedback group. Therefore, the outcome was not due to nonspecific factors and could be attributed to feedback-specific effects. Changes in skin conductance level showed that neck muscle relaxation was not simply mediated by a general reduction of “arousal.” Significant improvements of extent of head deviation, and range of movement of the head, as well as reductions of depression were present, which were not different in the two groups. At the end of treatment, no patient was asymptomatic. Any therapeutic benefit was generally maintained at follow-up. The results and the procedural simplicity of RGP make the issue of cost-efficacy of EMG biofeedback a pertinent one. Further controlled outcome studies of EMG biofeedback treatment of torticollis with larger samples are required.

Procedural memory and neurological disease

Abstract Dissociations between different aspects of learning and memory in patients with amnesic syndromes and various neurodegenerative diseases has led to a fundamental revision of the taxonomy of human memory, and a greater understanding of its neurobiological basis. It has been suggested that, while lesions to temporal and diencephalic structures leave procedural learning intact, neurological disorders involving the striatum lead to deficits in this aspect of learning. However, as comparative evidence has accumulated on a variety of procedural tasks, it has become clear that different neurological diseases lead to varying patterns of impaired and intact performance. This has led to a revision of the concept of a unified procedural system in favour of parallel, independent systems, only some of which involve the striatum. There is a danger, however, that the effort to fit the patterns of functional association and dissociation into a neuroanatomical framework may be premature, It is suggested that the ...

SEXUAL FUNCTION IN PATIENTS WITH PARKINSONS-DISEASE AND THEIR PARTNERS

Sexual function in patients with Parkinsons disease has received virtually no attention. There are many reasons (physical, psychological and social), why such patients might experience problems within their sexual relationships. A group of patients and their partners completed a series of self-report measures, aimed at assessing sexual function and a range of factors which might be associated with any difficulties. The results revealed a high level of dysfunction, not just in the patients but also in their partners. Most effected were the couples in which the patient was male. A range of problems were reported by both patients and their partners. These were, in turn, associated with a range of variables relating to the disease, psychological and social factors. No simple causal model was suggested, and a multimodal therapeutic approach might be expected to have most benefit.