Alterations in cognitive performance and affect-arousal state during fluctuations in motor function in Parkinson's disease

Executive dysfunction and cognitive decline, a non-motor symptom of Parkinson's disease captured in animal models

The non-motor symptoms of Parkinson's disease (PD) have gained increasing attention in recent years due to their significant impact on patients' quality of life. Among these non-motor symptoms, cognitive dysfunction has emerged as an area of particular interest where the clinical aspects are covered in Chapter 2 of this volume. This chapter explores the rationale for investigating the underlying neurobiology of cognitive dysfunction by utilising translational animal models of PD, from rodents to non-human primates. The objective of this chapter is to review the various animal models of cognition that have explored the dysfunction in animal models of Parkinson's disease. Some of the more advanced pharmacological studies aimed at restoring these cognitive deficits are reviewed, although this chapter highlights the lack of systematic approaches in dealing with this non-motor symptom at the pre-clinical stages.

Effects of cholinesterase inhibition on attention and working memory in Lewy body dementias

Cholinesterase inhibitors are frequently used to treat cognitive symptoms in Lewy body dementias (Parkinson's disease dementia and dementia with Lewy bodies). However, the selectivity of their effects remains unclear. In a novel rivastigmine withdrawal design, Parkinson's disease dementia and dementia with Lewy bodies patients were tested twice: once when taking rivastigmine as usual and once when they had missed one dose. In each session, they performed a suite of tasks (sustained attention, simple short-term recall, distractor resistance and manipulating the focus of attention) that allowed us to investigate the cognitive mechanisms through which rivastigmine affects attentional control. Consistent with previous literature, rivastigmine withdrawal significantly impaired attentional efficacy (quicker response latencies without a change in accuracy). However, it had no effects on cognitive control as assessed by the ability to withhold a response (inhibitory control). Worse short-term memory performance was also observed when patients were OFF rivastigmine, but these effects were delay and load independent, likely due to impaired visual attention. In contrast to previous studies that have examined the effects of dopamine withdrawal, cognitively complex tasks requiring control over the contents of working memory (ignoring, updating or shifting the focus of attention) were not significantly impaired by rivastigmine withdrawal. Cumulatively, these data support that the conclusion that cholinesterase inhibition has relatively specific and circumscribed-rather than global-effects on attention that may also affect performance on simple short-term memory tasks, but not when cognitive control over working memory is required. The results also indicate that the withdrawal of a single dose of rivastigmine is sufficient to reveal these impairments, demonstrating that cholinergic withdrawal can be an informative clinical as well as an investigative tool.

Altered directed connectivity during processing of implicit versus explicit predictive stimuli in Parkinson's disease patients

The study investigated the role of top-down versus bottom-up connectivity, during the processing of implicit or explicit predictive information, in Parkinson's disease (PD). EEG was recorded during the performance of a task, which evaluated the ability to utilize either implicit or explicit predictive contextual information in order to facilitate the detection of predictable versus random targets. Thus, subjects performed an implicit and explicit session, where subjects were either unaware or made aware of a predictive sequence that signals the presentation of a subsequent target, respectively. We evaluated EEG event-related directed connectivity, in PD patients compared with healthy age-matched controls, using phase transfer entropy. PD patients showed increased top-down frontal-parietal connectivity, compared to control subjects, during the processing of the last (most informative) stimulus of the predictive sequence and of random standards, in the implicit and explicit session, respectively. These findings suggest that PD is associated with compensatory top-down connectivity, specifically during the processing of implicit predictive stimuli. During the explicit session, PD patients seem to allocate more attentional resources to non-informative standard stimuli, compared to controls. These connectivity changes shed further light on the cognitive deficits, associated with the processing of predictive contextual information, that are observed in PD patients.

Body awareness training in the treatment of wearing-off related anxiety in patients with Parkinson's disease: Results from a pilot randomized controlled trial

BACKGROUND

In Parkinson's disease (PD) patients, fluctuations in symptoms commonly occur after many years of dopamine replacement therapy. The so-called wearing-off phenomenon exists of both motor and non-motor symptoms, such as rigidity and anxiety. Current treatment options are limited and an integrated approach is needed to address the complex interactions between motor and non-motor symptoms. Since wearing-off is eventually inevitable, treatment needs to focus on coping, acceptance and self-efficacy. We developed the body awareness training, named BEWARE, combining physical therapy with acceptance and commitment therapy to help PD patients deal better with wearing-off related anxiety (WRA).

METHODS

This was an investigator-blinded randomized controlled trial. Forty PD patients with WRA were randomly assigned to the BEWARE or to the treatment as usual (TAU) condition. Assessments were performed prior to and immediately after the treatment period, and at 3-months follow up. The primary outcome was self-efficacy, secondary outcomes focused on mobility, daily functioning, anxiety, depression and quality of life.

RESULTS

There was no significant improvement in self-efficacy in the BEWARE treatment condition when compared to TAU. However, standing balance and emotional wellbeing showed a significant improvement, and feelings of stigmatization showed a trend-significant decrease in the BEWARE condition.

CONCLUSIONS

We consider the BEWARE training to be a promising therapeutic approach to address WRA. Improvement points from the participants included 1) less frequent but longer therapy sessions; 2) active involvement of caregivers; and 3) the development of a supportive workbook. The optimized treatment protocol needs further evaluation in a phase III RCT.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02054845.

A Randomized Clinical Trial of Atomoxetine for Mild Cognitive Impairment in Parkinson's Disease

Background

Mild cognitive impairment in Parkinson's disease (PD-MCI) is associated with diminished norepinephrine from the locus coeruleus to the prefrontal cortex. Atomoxetine is a specific norepinephrine reuptake inhibitor that has been approved by the US Food and Drug Administration to treat attention deficit hyperactivity disorder in adults. The authors hypothesized that atomoxetine would improve attention and executive functioning in patients with PD-MCI.

Methods

Thirty participants who met Movement Disorder Society Task Force Level I criteria for PD-MCI were enrolled in a randomized controlled trial of atomoxetine. Cognitive evaluations were performed at baseline and after 10 weeks of treatment or placebo. A safety visit was performed at Week 12. A global statistical test was used to examine treatment effects on standardized tests of attention, working memory, processing speed, and set shifting (primary outcome measure). Secondary outcomes included cognitive measures hypothesized to be insensitive to atomoxetine, the Conners Adult Attention Deficit Hyperactivity Disorder Rating Scale, and safety measures.

Results

Fifteen participants were randomized to each arm. Groups were similar on medical and demographic variables and baseline cognition. Three serious adverse events occurred; 2 on atomoxetine (syncope, isolated episode of atrial fibrillation) and 1 on placebo (atrial fibrillation). The global statistical test of primary outcome measures did not reveal a significant difference between groups. However, significant improvements were observed for atomoxetine but not placebo on subjective measures of attention and impulsivity (Conners Adult Attention Deficit Hyperactivity Disorder Rating Scale).

Conclusions

Atomoxetine treatment produced subjective, but not objective, improvements in PD-MCI. Failure to detect objective differences may be due to insensitivity of cognitive tests or severity of cognitive deficits in the study participants.

Changes in Verbal Fluency in Parkinson's Disease

Background

The test for semantic verbal fluency is quick and easy to administer. Decreases in semantic verbal fluency would suggest executive dysfunction among individuals with Parkinson's disease (PD).

Methods

The National Parkinson Foundation's Outcomes Project is a multicenter study that seeks to determine best practices in PD management. We analyzed data from the baseline and two annual follow-up visits to determine the annual rate of verbal fluency change and determinants of that change. Linear mixed modeling was used to assess relationships between verbal fluency, clinical characteristics, quality of life, and caregiver burden.

Results

There were 1,322 participants with an average age of 67.3 years, of whom 37% were women. Mean baseline verbal fluency scores at baseline were 18.81 (standard deviation = 6.25). Verbal fluency scores did not change among patients who were at our cohort's average age and average PD duration (8.4 years) and who had no other associated conditions (beta = -0.02; P = 0.80). Verbal fluency, however, did decrease for individuals with PD duration greater than the average (beta = -0.25; P = 0.03), age greater than the average (beta = -0.022; P < 0.01), a Hoehn and Yahr >=3 (beta = -0.31; P = 0.04), and in those with cardiovascular disease (beta = -0.32; P = 0.01) or psychiatric symptomatology (beta = -0.34; P = 0.01). Individuals with higher verbal fluency scores had better quality of life (P < 0.01) and decreased caregiver burden (P < 0.01).

Conclusions

Clinicians should monitor verbal fluency scores to evaluate cognitive decline among individuals with PD. Modifiable risk factors for verbal fluency changes include psychiatric symptomatology and cardiovascular disease. Clinicians may use verbal fluency testing to identify individuals at risk for decreased quality of life and increased caregiver burden, allowing for focused interventions.

Improvements in manual dexterity relate to improvements in cognitive planning after assisted cycling therapy (ACT) in adolescents with down syndrome

We have previously reported beneficial effects of acute (i.e., single session) Assisted Cycling Therapy (ACT) on manual dexterity and cognitive planning ability in adolescents with Down syndrome (DS). In the present study, we report the chronic effects of eight weeks of ACT, voluntary cycling (VC), and no cycling (NC), on the same measures in adolescents with DS. Participants completed 8 weeks of ACT, VC, or NC. Those in the ACT and VC groups completed 30min sessions three times per week on a stationary bicycle. During ACT, the mechanical motor of the bicycle augmented the cadence to a rate which was on average 79% faster than the voluntary cadence. During VC, the participants pedaled at a self-selected rate. Unimanual dexterity scores as measured with the Purdue Pegboard test (PPT) improved significantly more for the ACT and VC groups compared to the NC group. ACT lead to greater improvements than VC and NC in the assembly sub-test, which is a task that requires more advanced temporal and spatial processing. The ACT group improved significantly more than the VC group and non-significantly more than the NC group in cognitive planning ability as measured by the Tower of London test (ToL). There were also significant correlations between the assembly subtest of the PPT and all measures of the ToL. These correlations were stronger during post-testing than pre-testing. Pre-post changes in the combined PPT score and ToL number of correct moves correlated positively in the ACT group. These results support the efficacy of the salutary effects of ACT on global fine motor function and executive function in DS. Additionally, the performance on complex bimanual dexterity tasks appears to be related to the capacity of cognitive planning ability. This research has important implications for persons with movement deficits that affect activities of daily living.

BEWARE: Body awareness training in the treatment of wearing-off related anxiety in patients with Parkinson's disease: study protocol for a randomized controlled trial

BACKGROUND

The wearing-off phenomenon in patients with Parkinson's disease (PD) is a complication of prolonged levodopa usage. During this phenomenon, motor symptoms such as rigidity and freezing re-emerge. This is often accompanied by non-motor symptoms, including anxiety, the so-called wearing-off related anxiety (WRA). Current treatment options are limited and typically focus on either the physical or mental aspects of wearing-off. An integrated approach seems warranted in order to optimally address the complex reciprocal interactions between these aspects. Also, because wearing-off is eventually inescapable, treatment needs to focus on coping, acceptance, and self-efficacy. We therefore developed an integrated body awareness intervention, combining principles from physical therapy with acceptance and commitment therapy to teach patients to deal with WRA. This study will investigate whether this new intervention, named BEWARE, is more effective than treatment as usual in increasing self-efficacy.

METHODS/DESIGN

This is a single-blinded randomized controlled trial in 36 PD patients who experience WRA. Subjects will be recruited from the outpatient clinic for movement disorders of the VU University Medical Center. After providing written informed consent, patients will be randomly assigned to an experimental (BEWARE) or treatment-as-usual (physical therapy) group. Clinical assessments will be performed prior to the intervention, directly after the 6-week intervention period, and at 3-month naturalistic follow-up by a blinded investigator not involved in the study. The primary outcome measure is self-efficacy, and secondary outcomes focus on mobility, daily functioning, anxiety, and quality of life.

DISCUSSION

Because wearing-off is an inevitable consequence of levodopa therapy and current treatment options are insufficient, a multidisciplinary intervention that addresses both physical and mental aspects of wearing-off in PD may foster additional benefits for treating WRA in PD patients over mono-disciplinary care alone.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02054845. Date of registration: 30 January 2014.

Behavioral characterization of A53T mice reveals early and late stage deficits related to Parkinson's disease

Parkinson's disease (PD) pathology is characterized by the formation of intra-neuronal inclusions called Lewy bodies, which are comprised of alpha-synuclein (α-syn). Duplication, triplication or genetic mutations in α-syn (A53T, A30P and E46K) are linked to autosomal dominant PD; thus implicating its role in the pathogenesis of PD. In both PD patients and mouse models, there is increasing evidence that neuronal dysfunction occurs before the accumulation of protein aggregates (i.e., α-syn) and neurodegeneration. Characterization of the timing and nature of symptomatic dysfunction is important for understanding the impact of α-syn on disease progression. Furthermore, this knowledge is essential for identifying pathways and molecular targets for therapeutic intervention. To this end, we examined various functional and morphological endpoints in the transgenic mouse model expressing the human A53T α-syn variant directed by the mouse prion promoter at specific ages relating to disease progression (2, 6 and 12 months of age). Our findings indicate A53T mice develop fine, sensorimotor, and synaptic deficits before the onset of age-related gross motor and cognitive dysfunction. Results from open field and rotarod tests show A53T mice develop age-dependent changes in locomotor activity and reduced anxiety-like behavior. Additionally, digigait analysis shows these mice develop an abnormal gait by 12 months of age. A53T mice also exhibit spatial memory deficits at 6 and 12 months, as demonstrated by Y-maze performance. In contrast to gross motor and cognitive changes, A53T mice display significant impairments in fine- and sensorimotor tasks such as grooming, nest building and acoustic startle as early as 1-2 months of age. These mice also show significant abnormalities in basal synaptic transmission, paired-pulse facilitation and long-term depression (LTD). Combined, these data indicate the A53T model exhibits early- and late-onset behavioral and synaptic impairments similar to PD patients and may provide useful endpoints for assessing novel therapeutic interventions for PD.

Contextual processing deficits in Parkinson's disease: the role of the frontostriatal system

OBJECTIVE

We investigated the role of the frontostriatal system in contextual processing, by examining neural correlates of local contextual processing in Parkinson's disease (PD). Local context was defined as the occurrence of a short predictive series of visual stimuli occurring before delivery of a target event.

METHODS

EEG was recorded in eight PD patients and eight controls. Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences including a predictive sequence signaling the occurrence of a subsequent target event. Subjects pressed a button in response to targets. Peak P3b amplitude and latency were evaluated for targets after predictive and non-predictive sequences.

RESULTS

Behavioral and electrophysiological measures showed that controls processed predicted and random targets differentially, while PD patients processed these similarly. Reaction times were shorter for predictable than for random targets in controls but not in patients. PD patients failed to generate the expected P3b latency shift between predicted and random targets, which is observed in controls.

CONCLUSIONS

These findings show that predictive local context effects on target detection are altered in PD patients.

SIGNIFICANCE

The findings suggest a key role for the frontostriatal system in contextual processing.

Evaluation of anxiety in Parkinson's disease with some commonly used rating scales

This study assessed the concurrent validity of the State-Trait Anxiety Inventory (STAI), the Hospital Anxiety and Depression Scale (HADS) and the Hamilton Anxiety Scale (Ham-A) for evaluating anxiety in a group of 46 Parkinson's disease (PD) patients. The magnitude of correlations between the scales was high (all p<0.01), indicating a good concurrent validity. The item-by item analysis indicated that the main characteristics of anxiety in PD patients were 'inability to relax', 'restlessness or inability to feel calm' and 'feeling tense'. The association between anxiety, as measured by the HADS-A, with demographic characteristics or clinical features of PD was not significant, supporting existing data suggesting that anxiety in PD is not closely correlated with the severity of motor symptoms or the degree of disability. The HADS-A may be the most appropriate scale for documenting patient-reported anxiety in depression.

[Non-motor fluctuations in Parkinson's disease]

Nonmotor fluctuations (NMF) in Parkinson's disease are nonmotor symptoms that occur in coincidence with motor fluctuations or independently. Long under-assessed, NMF are now recognized as frequent and sometimes involving a greater degree of disability than motor fluctuations. They can be classified in three categories: dysautonomic, cognitive/psychiatric and sensory/pain. Recognition of these nonmotor fluctuations as part of Parkinson's disease has important implications. Some symptoms such as dyspnea, chest pain, or abdominal pains can mimic cardiac or gastrointestinal emergencies. The underlying pathogenic mechanisms of NMF are not well known. The dopaminergic system is probably involved via modulation of other systems (serotoninergic, adrenergic) since NMF usually respond to dopaminergic treatment. Subthalamic nucleus deep brain stimulation alleviates NMF-- particularly sensory, dysautonomic and cognitive fluctuations--while psychic fluctuations respond less consistently to this treatment. The development of new instruments that enable a comprehensive and precocious assessment of NMF is important for optimized management of advanced Parkinson's disease.

Effects of levodopa and subthalamic nucleus stimulation on cognitive and affective functioning in Parkinson's disease

In Parkinson's disease (PD), levodopa and subthalamic nucleus (STN) stimulation lead to major improvement in motor symptoms. Effects of both treatments on cognition and affective status are less well understood. Motor, cognitive, and affective symptoms may relate to the dysfunctioning of parallel cortico-striatal loops. The aim of this study was to assess cognition, behavior, and mood, with and without both treatments in the same group of PD patients. A group of 22 nondemented PD patients was included in this study. Patients were tested twice before surgery (off and on levodopa) and twice 3 months after surgery (OFF and ON STN stimulation, off levodopa). Cognitive and affective effects of STN stimulation and levodopa had some common, but also different, effects. STN stimulation improved performance on the planning test, associated with the dorsolateral prefrontal cortex. However, the treatments had opposite effects on tests associated with the orbitofrontal cortex; specifically, levodopa impaired while STN stimulation improved performance on the extinction phase of a reversal/extinction task. Acutely, both treatments improved motivation and decreased fatigue and anxiety. On chronic treatment (3 months after surgery), depression improved, whereas apathy worsened 3 months after surgery. To conclude, there were significant but contrasting effects of levodopa and STN stimulation on cognition and affective functions.

Visual event-related potentials under different interstimulus intervals in Parkinson's disease: Relation to motor disability, WAIS-R, and regional cerebral blood flow

We have introduced S1-S2 paradigm (task S) as well as oddball paradigm (task O) visual event-related potentials (ERPs) under different interstimulus intervals (ISIs) in Parkinson's disease (PD). ERP measurements were correlated with motor disability, WAIS-R, and regional cerebral blood flow (rCBF). The 'group' influence was characterized by longer latency for P300, N200, and reaction time and decreased P300 amplitude in PD. Both P300 latency and reaction time during task O showed significantly longer latency in longer ISI condition. Our results revealed 'ISI' influence on ERPs during task S and significant correlation between ERPs and rCBF in task S.

Early sensory information processes are enhanced on visual oddball and S1-S2 tasks in Parkinson's disease: a visual event-related potentials study

To observe sensory and cognitive information processing in Parkinson's disease (PD), 34 PD patients and 26 controls were investigated. A visual oddball paradigm and an S1-S2 paradigm were employed to record the early (P1, N1, P2) and late (N2, P3) event-related potentials (ERPs) at Cz, Pz and Oz. Results showed: (1) enlarged P1 amplitude at all electrode locations on both tasks, (2) shortened N1 latency and enlarged P2 amplitude at Oz on both tasks, (3) enlarged N1 amplitude at Cz during an oddball paradigm, (4) delayed N2 latency and decreased N2, P3 amplitude on both tasks, and (5) delayed P3 latency and reaction time during the S1-S2 paradigm. Abnormal ERP changes were correlated with worsened scores on Wechsler Adult Intelligence Scale-Revised and motor dysfunction scales in PD. We surmise overactive aspects or failed inhibitory modulation of sensory information processing in the early ERP stage and deficient cognitive information processing during the late ERP stage in PD.

Depressed mood and executive dysfunction in early Parkinson's disease

OBJECTIVES

Studies on neuropsychological functions in early Parkinson's disease (PD) have reported changes with respect to memory and executive control related to dysfunction of fronto-striatal circuitry. The question has been raised, however, whether these findings are at least partly influenced by depression, which as such can also lead to cognitive impairments that depend on the functional integrity of the prefrontal cortex.

MATERIAL AND METHODS

In the present investigation early non-depressed PD patients (NPD), early PD patients with mild depressive symptoms (DPD), patients with primary depression (DEP) and healthy controls (HC) completed a range of neuropsychological tests.

RESULTS

Group comparisons revealed impairments of DPD patients in comparison with HC with respect to verbal fluency, short-term memory and concept formation. In addition they showed mild working-memory deficits.

CONCLUSIONS

In summary the present results indicate that depressed mood in early PD may exacerbate cognitive impairments. Thus careful assessment of affective variables in PD should be an integral part of the treatment of PD.

Information processing speed and sentence comprehension in Parkinson's disease

This study tests the hypothesis that sentence comprehension difficulty in Parkinson's disease (PD) is related in part to altered information processing speed that plays a crucial role in grammatical processing. The authors measured information processing speed in 32 PD patients without dementia using a lexical list-priming paradigm in which the interstimulus interval (ISI) between the prime and the target varied. Sentence comprehension accuracy was also assessed in 22 of these patients. Sentence comprehension accuracy for object-relative center-embedded sentences was impaired in a subgroup of PD patients. This subgroup of PD patients primed at an abnormally long ISI. Similarly, only PD patients who primed at a long ISI had greater difficulty understanding sentences with an object-relative clause than a subject-relative clause. Findings suggest that slowed information processing speed contributes to sentence comprehension difficulty in PD.

Impaired attention modulation of the blink reflex R3 component in Parkinson's disease: a non-task warning paradigm study

PURPOSE

the aim of this experimental study was to evaluate the attention modulating actions on the polysynaptic component of blink reflex responses and especially of the R3 component in patients suffering from Parkinson's Disease (PD). To this end, a non-task warning paradigm was adopted.

METHODS

attention processing was evaluated by means of a non-task paradigm in 55 patients suffering from PD. Subjects were presented with a visual 'warning' prestimulus and the blink reflex (BR) analyzed with special regard for any modulation of its polysynaptic components (R2-R3).

RESULTS

The mean amplitude of the post-warning R3 component (PW-R3c) of 'de novo' PD patients was 62% of the corresponding component following unannounced stimuli, a figure which differs significantly from both treated PD patients (18.9%) and control subjects (15.4%). De novo patients subsequently started on L-dopa therapy exhibited a more pronounced inhibition of the R3 component after warning stimulus, as the PW-R3c percentage decreased. Inversely, treated patients whose therapy was withheld showed decreased inhibition of this component. Regarding R2, the mean PW-R2c in the de novo patients differed slightly from that of the treated patients (P<0.05), but not from that of the control subjects. Such a finding may be attributable to a specific effects on the excitability of the polysynaptic responses.

CONCLUSIONS

Attention disorders in PD have been well documented by means of this kind of non-task warning paradigm, which appears to probe the modulation of the BR R3 component, even if the interpretation of this R3 changes suggesting a specific alteration of attention processing must be put forward extremely carefully, because something similar, but less evident, appears also for R2.

Depression in Parkinson's disease

Depression is common in Parkinson's disease (PD), and its identification and treatment are critically important in disease management. Despite depression's high prevalence and major impact on patient quality of life, questions remain regarding its epidemiology and preferred treatment. The authors of this paper summarize available information on the epidemiology of depression in PD, review treatment options, and discuss possible interactions between antidepressants and other agents. This information may help guide clinical treatment and define the need for further studies.

Dopamine supports sentence comprehension in Parkinson's Disease

OBJECTIVE

To determine the role of dopamine in the executive resource component of sentence comprehension.

METHODS

We studied sentence-picture matching in 20 right-handed, non-demented, native English speakers with mild Parkinson's disease (PD) when 'on' and 'off' their levodopa, taking into account disease duration to control for endogenous dopamine metabolism. We also administered a verbal working memory measure that does not involve specific grammatical manipulations.

RESULTS

PD patients 'off' levodopa demonstrated a significant discrepancy in their comprehension of grammatically complex sentences compared to grammatically simpler sentences that was not evident when PD patients were 'on' levodopa. An error analysis demonstrated that impaired comprehension of grammatically complex sentences when 'off' levodopa was associated with poorer performance on foils requiring working memory resources. Performance on an independent measure of verbal working memory correlated only with comprehension of grammatically complex sentences during levodopa supplementation, but working memory according to this measure did not differ during 'on' and 'off' states.

CONCLUSION

Dopamine supports the executive resources contributing to sentence comprehension in PD.

Chronic effects of dopaminergic replacement on cognitive function in Parkinson's disease: a two-year follow-up study of previously untreated patients

BACKGROUND

The cognitive effects of dopaminergic treatment in Parkinson's disease (PD) are still controversial.

OBJECTIVE

To evaluate, in previously untreated patients with PD, whether chronic dopaminergic stimulation produces significant cognitive changes; whether they are sustained beyond the period of a few months; and whether the cognitive status of two motor-comparable groups is differently affected by levodopa and pergolide.

DESIGN AND SUBJECTS

Parallel, randomized open study with blind neuropsychologic evaluation of 20 consecutive de novo patients with PD before and 3, 6, 12, 18, and 24 months after monotherapy with levodopa (n = 10) or pergolide (n = 10; 6-month monotherapy; pergolide + levodopa thereafter).

RESULTS

Both treatments were associated with a significant improvement in motor scores and in tests assessing learning and long-term verbal and visual memory, visuospatial abilities, and various frontal tasks. While improvement in motor scores persisted, improvement in activities of daily living and in semantic fluency, Luria's rhythm and motor and long-term memory tests was not sustained at the 24-month examination. Further, performance on attentional, short-term memory, and the Stroop tests did not change over the course of the study.

CONCLUSIONS

Both treatments were associated with incomplete but long-lasting (18 mos) improvement in many cognitive tasks which declined thereafter, suggesting that dopaminergic replacement is not enough to compensate for all cognitive deficits of PD.

Role of dopamine in learning and memory: implications for the treatment of cognitive dysfunction in patients with Parkinson's disease

Along with dementia, Parkinson's disease (PD) is associated with subtle but widespread cognitive impairment even in the absence of clinically apparent cognitive decline. Many of the deficits are reminiscent of those observed in patients with lesions of the prefrontal cortex, that is, failure in executive function that involves skills required for anticipation, planning, initiation and monitoring of goal-directed behaviours. This paper reviews the dopaminergic brain circuitry, and preclinical and clinical evidence supporting the regulation of prefrontal cortex activity by dopamine, and the role of dopamine in cognitive impairment in patients with PD. It addresses the need to integrate these facts and the findings of positive, neutral or detrimental frontal cognitive response to dopaminergic drugs in PD which should be viewed mainly in the context of methodological differences for subject selection. The cognitive effect of levodopa does not much depend on a neuropsychological specificity of the drug, the years of evolution of the disease or the severity of the motor signs. Instead, it may be a function of the level of dopamine depletion in different parts of the basal ganglia and prefrontal cortex. Consequently, dopaminergic agents may enhance cognitive functions in some patients and impair them in others. De novo patients tend to improve during the first year of treatment; stable responders to oral levodopa tend to show no changes; and wearing-off responders tend to deteriorate with acute levodopa challenge. Enhancement and impairment of cognitive function with dopaminergic treatment is incomplete and task-specific, suggesting the need to integrate the above dopamine facts with other neurotransmitter systems findings in PD. Meanwhile, such cognitive dissociation can be useful in refining the definition of the cognitive deficit in PD patients without dementia and emphasising the need to develop new and specific strategies for treatment.

The behavioral complications of pallidal stimulation: a case report

We report a case of recurrent manic episodes associated with chronic deep brain stimulation (DBS) targeting globus pallidus (GP) in the treatment of Parkinson's disease (PD). Cardinal PD symptoms and dyskinesia improved with DBS, and neuropsychological testing found improvements in visuospatial measures associated with left DBS and in verbal memory with right DBS when compared to the patient's preoperative baseline. Under conditions of right, left, and bilateral DBS, the patient experienced bouts of mania and hypomania lasting several days at a time. Positron emission tomography (PET) with (15)O-labeled water was performed after his first manic episode under four conditions: no stimulation, right DBS, left DBS, and bilateral DBS. Although no manic switch occurred during the course of the PET study, all three DBS conditions were associated with decreases in regional flow in the left parahippocampus and hippocampus and right mid-cingulate gyrus. Increases in flow in left inferior frontal area, bilateral insula, dorsolateral prefrontal cortex, and cuneus were common to all DBS conditions. GP stimulation in PD may be associated with behavioral and cognitive effects. Distributed blood flow changes observed with pallidal DBS support a role for the pallidum in cognition and affective regulation.

Cortical dysfunction in non-demented Parkinson's disease patients: a combined (31)P-MRS and (18)FDG-PET study

Regional cerebral phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) was performed in 10 non- demented Parkinson's disease patients and nine age-matched control subjects. Five of the patients undergoing (31)P-MRS and four additional Parkinson's disease patients had cerebral 2-[(18)F]fluoro-2-deoxy-D-glucose PET ((18)FDG-PET), the results of which were compared with those of eight age-matched control subjects. All Parkinson's disease patients underwent neuropsychological testing including performance and verbal subtests of the Wechsler Adult Intelligence Scale-Revised, Boston Naming Test, Controlled Oral Word Association test (FAS Test) and California Learning Test to exclude clinical dementia. (31)P MR spectra from right and left temporo-parietal cortex, occipital cortex and a central voxel incorporating basal ganglia and brainstem were obtained. (31)P MR peak area ratios of signals from phosphomonoesters (PMEs), inorganic phosphate (P(i)), phosphodiesters (PDEs), alpha-ATP, gamma-ATP and phosphocreatine (PCr) relative to beta-ATP were measured. Relative percentage peak areas of PMEs, P(i), PDEs, PCr, and alpha-, beta- and gamma-ATP signals were also measured with respect to the total (31)P-MRS signal. Significant bilateral increases in the P(i)/beta-ATP ratio were found in temporoparietal cortex (P = 0.002 right and P = 0.014 left cortex) for the non-demented Parkinson's disease patients compared with controls. In the right temporoparietal cortex, there was also a significant increase in the mean relative percentage P(i) (P = 0.001). (18)FDG-PET revealed absolute bilateral reductions in glucose metabolism after partial volume effect correction in posterior parietal and temporal cortical grey matter (P < 0.01 and P < 0.05, respectively) for the Parkinson's disease group, using both volume of interest analysis and statistical parametric mapping. There were significant correlations between right temporoparietal P(i)/beta-ATP ratios and estimated reductions in performance IQ (r = 0.96, P < 0.001). Left temporoparietal P(i)/beta-ATP ratios correlated with full scale IQ and verbal IQ (r = -0.82, P = 0.006, r = -0.86, P = 0.003, respectively). In summary, temporoparietal cortical hypometabolism was seen in non-demented Parkinson's disease patients with both (31)P-MRS and (18)FDG-PET, suggesting that both glycolytic and oxidative pathways are impaired. This dysfunction may reflect either the presence of primary cortical pathology or deafferentation of striato-cortical projections. (31)P-MRS and (18)FDG-PET may both provide useful predictors of future cognitive impairment in a subset of Parkinson's disease patients who go on to develop dementia.

Neuropsychiatric aspects of Parkinson's disease

Parkinson's disease (PD), a disorder characterized by movement abnormalities, is frequently complicated by psychiatric syndromes. Psychiatric assessment of the PD patient requires familiarity with the motor and cognitive aspects of PD, the various effects of antiparkinsonian medications, and how these relate to mental status changes and psychiatric phenomena. This review describes the various motor and nonmotor features of PD and focuses on the differential diagnosis of affective disorders in PD and their treatment.

Evidence for cortical dysfunction in clinically non-demented patients with Parkinson's disease: a proton MR spectroscopy study

OBJECTIVES

To investigate whether proton magnetic resonance spectroscopy (1H MRS) can detect cortical dysfunction in non-demented patients with Parkinson's disease, and to correlate changes with cognitive function on formal neuropsychological testing.

METHODS

Multivoxel 1H MRS was performed in 17 patients with levodopa treated idiopathic Parkinson's disease with out clinical dementia, and 10 age match ed control subjects. Measurements of N-acetylaspartate (NAA)/choline (Cho), NAA/creatine+phosphocreatine (Cr), and Cho/Cr were obtained from right and left temporoparietal cortex and occipital cortex. Fourteen patients with Parkinson's disease underwent a full battery of neuropsychological testing including performance and verbal subtests of the WAIS-R, Boston naming test, FAS test, and California verbal learning test.

RESULTS

There were significant temporoparietal cortex reductions in NAA/Cr ratios in right and left averaged spectra of the patients with Parkinson's disease (p=0.012 after Bonferroni correction) and in spectra contralateral to the worst clinically affected limbs of the patients with Parkinson's disease compared with controls (p = 0.003 after Bonferroni correction). There was a significant correlation between reduction in NAA/Cr ratios and measures of global cognitive decline, occurring independently of motor impairment (p=0.019).

CONCLUSIONS

This study suggests that 1H MRS can detect temporoparietal cortical dysfunction in non-demented patients with Parkinson's disease. Further longitudinal studies are needed to investigate whether these 1H MRS changes are predictive of future cognitive impairment in the subset of patients with Parkinson's disease who go on to develop dementia, or occur as part of the normal Parkinson's disease process.

Sentence processing in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative condition that is associated with the depletion of dopamine (DA)-containing neurons in specific brain regions. This article reviews one consequence of this defect-sentence comprehension difficulty in nondemented patients with PD. The first section describes the pattern of cognitive deficits seen in patients with PD, focusing specifically on their difficulties with language processing. Subsequent sections relate the profile of cognitive impairments in PD to studies investigating compromised DA metabolism in fronto-striatal brain regions. The findings suggest that the sentence comprehension deficit in PD is due in large part to limitations in the strategic distribution of cognitive resources such as selective attention that contribute to the processing of complex material. The physiological basis for this deficit appears to be associated with the disruption of a fronto-striatal cerebral network that is compromised following degradation of the DA projection system.

Acute and long-term administration of anticholinergics in Parkinson's disease: specific effects on the subcortico-frontal syndrome

Parkinson's Disease (PD) is often associated with a subcortico-frontal syndrome (SCFS) that is mainly characterized by executive dysfunctions. The complete biochemistry of these dysfunctions remain misunderstood. Most studies have focused on the well-known nigro-striatal dopaminergic degenerations of PD, but a more satisfying understanding of the SCFS has come from the study of the cholinergic systems. We present here two new experiments carried out with long-term and acute anticholinergic treatments in PD. In the first experiment, the effects of a 2-week treatment with trihexyphenidyl were compared to those observed under placebo on a neuropsychological battery. Results showed that anticholinergic-induced deficits in PD were exclusively concerned with executive functions. In the second experiment, the effects of an acute subclinical dose of scopolamine were compared between normal controls and PD patients who were devoid of cognitive deficit on a subset of executive tasks. Results indicates that PD patients but not normal controls developed a transient SCFS for the duration of the drug action. In contrast to other populations with cholinergic depletions-such as Alzheimer's disease-cholinergic blockade in PD exacerbates specifically the SCFS. Such a discrepancy between these two neuropsychological profiles are discussed in terms of the specificity of the underlying cholinergic lesions.

The relation of putamen and caudate nucleus 18F-Dopa uptake to motor and cognitive performances in Parkinson's disease

The contribution of striatal (caudate nucleus-putamen) dopaminergic deficiency to the severity of motor signs is well established in Parkinson's disease (PD), while its role in the occurrence of cognitive and mood changes remains unresolved. We therefore measured in 27 non-demented PD patients and 10 age-matched controls striatal uptake of [18F]-6-fluoro-L-Dopa (F-Dopa) with PET, and mood (Beck depression), memory (Grober-Buschke), frontal executive functions (verbal fluency and Wisconsin card sorting), and attentional processing of sensory stimuli (N2-P3 auditory event-related potentials--ERPs). Locomotor disability of patients was assessed by Hoehn and Yahr score and Unified Parkinson's Disease Rating Scale (UPDRS). ANOVA showed that memory, but neither frontal lobe functions nor ERPs, was significantly altered in PD patients, whereas indices of depression were found only in advanced PD. The F-Dopa rate constant Ki was significantly reduced in the striatum, more in putamen than caudate nucleus, and inversely correlated with disease duration. A significant inverse correlation was found between both putamen and caudate nucleus Ki and Hoehn and Yahr score, and between putamen--but not caudate nucleus Ki --and UPDRS motor score. Principal components analysis (PCA) of PD patients Ki values and mood, cognitive and ERP parameters gave a three-factor solution. Variables contributing to factor 1 were memory score and N2-P3 ERP latencies, those to factor 2 were striatal Ki values, and those to factor 3 frontal executive performances. Depression did not segregate with any variable. Our findings suggest that unlike locomotor disability, cognitive abilities and mood state of non-demented PD patients are for the most part unrelated to striatal dopaminergic depletion and may result from dysfunction of extra-striatal dopaminergic or from non-dopaminergic systems.

Differential diagnosis of the major progressive dementias and depression in middle and late adulthood: a summary of the literature of the early 1990s

There is a preponderance of research on the neuropsychology of the various dementias. There are also direct comparisons between two or more dementias available in the literature. This paper sought to summarize the most recent literature, primarily from 1990 through mid-1996, including recent reviews of the literature from previous decades. The purpose was to provide, in one location, a summary of neuropsychological (i.e., cognitive, motor, and psychiatric) characteristics of major noninfectious, progressive dementias and depression of middle and late adulthood. It is hoped that this review, particularly a summary table provided, will serve as a guide in the differential diagnosis of the dementias by clinicians. In addition to Alzheimer's disease, vascular dementias, Parkinson's disease, Lewy body dementia, Huntington's disease, and frontal lobe dementia, the impact of depression on cognitive functioning is covered given the frequency with which neuropsychologists are asked to differentiate depression from primary dementia.

Cognitive improvement during Tolcapone treatment in Parkinson's disease

The aim of this study was to evaluate the effects of Tolcapone, a reversible, selective inhibitor of catechol-O-methyltransferase, on the cognitive function of eight patients with advanced Parkinson's disease. They underwent neuropsychological and motor assessment at baseline and were re-evaluated after 6 months. During this period, they received Tolcapone three times daily, while the L-dopa dosage was progressively reduced. Significant improvements were observed in the attentional task, auditory verbal short-term memory, visuo-spatial recall, constructional praxia and motor symptoms. These data suggest that treatment with Tolcapone, in combination with L-dopa therapy, may determine a significant improvement in cognitive resources of patients with advanced Parkinson's disease.

Deductive and inductive reasoning in Parkinson's disease patients and normal controls: review and experimental evidence

In the present study, fifty-four subjects were tested; twenty-seven with idiopathic Parkinson's disease and twenty-seven normal controls matched in age, education, verbal ability, level of depression, sex and socio-economic status. The subjects were tested on eight tasks. Five of the tasks were the classic deductive reasoning syllogisms, modus ponens, modus tollendo tollens, affirming the consequent, denying the antecedent and three-term series problems phrased in a factual context (brief scripts). Three of the tasks were inductive reasoning, including logical inferences, metaphors and similes. All tasks were presented to subjects in a multiple choice format. The results, overall, have shown nonsignificant differences between the two groups in deductive and inductive reasoning, an ability traditionally associated with frontal lobes involvement. Of the comparisons performed between subgroups of the patients and normal controls concerning disease duration, disease onset and predominant involvement of the left and/or right hemisphere, significant differences were found between patients with earlier disease onset and normal controls and between bilaterally affected patients and normal controls, demonstrating an additive effect of lateralization to reasoning ability.

Neuropsychological performance, disease severity, and depression in progressive supranuclear palsy

To investigate the relationship between disease severity, cognitive impairment and depression in progressive supranuclear palsy (PSP) we studied a group of 25 patients who fulfilled strict research criteria and 25 matched controls. Disease severity was judged from the duration of symptoms, level of physical disability using the Columbia Rating Scale (CRS), and the degree of eye movement abnormality. The neuropsychological battery was designed to assess attention and executive function, visual and auditory perception, semantic memory and language production. Although the PSP group were significantly impaired on almost all of these measures, the most profound deficits were on tests of sustained and divided attention. There was no correlation between cognitive impairment and either disease duration or scores on the CRS, but performance on tests of attention correlated significantly with the degree of ocular motor impairment. Depression was found to be common in PSP but did not correlate with any other parameters. It is concluded that the cognitive deficit in PSP is widespread and independent of depression. The association between the severity of eye movement disorder and deficits in sustained and divided attention leads us to postulate that pathology involving the midbrain periaqueductal region may be critical for breakdown in these fundamental processes.

Progression of motor and cognitive impairment in Parkinson's disease

We performed a longitudinal study (mean follow-up 86.7 months) to evaluate motor and mental deterioration in patients with Parkinson's disease. Of the original 91 patients, only 61 could be re-examined 7 years later and 11 of these had become demented (PD-Dems). PD-Dems were older with worse motor and, obviously, cognitive performance than non-demented parkinsonian patients (PDs). A global cognitive decay index (DI) was calculated for each patient. Based on this, non-demented PDs were further split into 38 stable parkinsonian patients (S-PDs) with DI-30% to +30%, and 10 deteriorated but non-demented parkinsonian patients (D-PDs) with a DI worse than -30% (as had PD-Dems). D-PDs were older and had greater motor impairment than S-PDs but did not differ from PD-Dems on these measures. D-PDs and PD-Dems deteriorated especially in attention, visuospatial and executive ability tests. Ageing seems to be the main predictive factor for mental deterioration.

Exercise and the psychological state of institutionalized elderly: a review

The present review examined the hypothesis that exercise facilitates psychological processes among institutionalized geriatric and psychogeriatric elderly persons. Studies of long-term psychogeriatric patients showed significant cognitive change following a period of moderate aerobic exercise. However, no lasting cognitive effect of long-term exercise was observed for those who became mentally or physically impaired in old age or who could not tolerate strenuous exercise. On the other hand, improvement in cognitive function was reported immediately following an exercise session among geriatric institutionalized patients. Neither long-term nor short-term exercise brought about changes in affect. Although most studies suffer serious methodological shortcomings, the common finding of improved cognitive function immediately following exercise suggests that physical activity does have some arousal effect on cognition in institutionalized elderly persons. More studies are needed to clarify the immediate versus long-term effect of exercise on psychological variables among institutionalized elderly as well as the relationship between physical fitness and cognitive change.

Neuropsychological correlates of L-deprenyl therapy in idiopathic parkinsonism

1. Monoaminergic neurotransmitter systems are known to play an important role in neuropsychological functions and they are impaired in dementia of DAT and PD. 2. L-deprenyl is a monoamine-enhancing drug which at low doses selectively inhibits MAO-B, an enzyme whose brain activity has been reported to increase in normal aging and neurodegenerative dementing disorders. 3. The authors studied the effects of L-deprenyl, 10 mg/day, on several cognitive domains in idiopathic parkinsonians without dementia. Ten out-patients, treated with levodopa plus DDI, were tested before receiving L-deprenyl and retested six months after they had been treated with the drug. A control group of ten parkinsonian out-patients treated with only levodopa plus DDI, matched for age, educational level, severity and duration of extrapyramidal disease, was tested by the same neuropsychological battery and retested after a comparable time interval. 4. Statistically significant changes were noted in the verbal and visuospatial learning performances of PD patients treated with the combination of L-deprenyl and levodopa.

Parkinson's disease and anxiety: comorbidity with depression

Parkinson's disease (PD) is frequently accompanied by symptoms of depression and anxiety. However, the relationship between anxiety and depression has not been rigorously defined in these patients. In this study, 42 patients with PD and 21 matched medical controls were evaluated using DSM-III-R criteria and a variety of psychiatric rating scales. Twelve (29%) PD patients but only one medical control had a formal anxiety disorder diagnosis. Of the 12 patients with PD who had an anxiety disorder diagnosis, 11 (92%) had a comorbid depressive disorder diagnosis. Of the 18 patients with a depressive disorder, 12 (67%) also had an anxiety disorder diagnosis. Furthermore, a stepwise regression analysis found that the depression measure explained 44% of the variance in anxiety measures whereas neither the severity of illness variables nor the levodopa dose contributed significantly to the variance. This study suggests that the excess anxiety found in PD patients is unlikely to be primarily a psychologic reaction to the illness or a side effect of levodopa treatment. Rather, we suggest that anxiety and depression are related manifestations of the underlying neurochemical changes of PD itself.

Incidental and intentional recall in Parkinson's disease: an account based on diminished attentional resources

The recall of common objects and their spatial location was examined in 65 patients with Parkinson's disease (PD) under conditions in which available attentional resources were manipulated by secondary task demands. PD patients were impaired at item recall particularly under intentional learning conditions but were unimpaired at recall of spatial location. These findings were similar in newly diagnosed, untreated cases as well as patients who had suffered with the disease for an average of 9.6 years. Test performance was not improved by levodopa therapy, despite it benefiting motor control, and was not impaired by anticholinergic medication. Item recall correlated significantly with other memory measures (particularly tasks of working memory) but only weakly with indices of physical disability and traditional frontal-lobe measures. Spatial recall, by contrast, correlated with memory quotient but no other cognitive measure and depression and disease duration failed to correlate significantly with performance on either recall task. These results are attributed to a deficit in attentional resources in PD that impairs performance most markedly for tasks and conditions that make the greatest demands upon effort.

Short-term memory and temporal ordering in early Parkinson's disease: effects of disease chronicity and medication

Studies of Parkinson's disease (PD) have shown impaired temporal ordering but interpretation may be confounded by task requirements and the effects of medication. We examined item recognition and recency discrimination in PD in relation to treatment and performance on other tests. Patients showed increased response latency and impaired recency discrimination only at short retention intervals. The deficits were greater in chronically medicated patients but treatment with levodopa, bromocriptine or anticholinergic drugs did not affect performance of newly diagnosed cases. The short-term memory deficits correlated with scores on tests of working memory, attention and executive function. These results do not indicate a generalised temporal ordering deficit in PD but suggest that much of the cognitive impairment in the disorder arises from attentional deficits affecting short-term and working memory.

Visuospatial memory deficits at different stages of Parkinson's disease

Groups of patients with idiopathic Parkinson's disease (PD), either medicated or unmedicated, were compared with matched groups of normal controls on a computerised battery of tests designed to investigate spatial working memory, visuospatial recognition memory and learning. The medicated PD patients were subdivided into those with mild and severe clinical disability on the basis of Hoehn and Yahr ratings, thus making three groups of PD patients in all. In a test of spatial recognition memory, a significant impairment was only evident in those PD patients who were medicated and had severe clinical symptoms (Hoehn and Yahr stage III-IV). In contrast, none of the three patient groups were impaired in a complementary test of visual pattern recognition memory. Whilst all three patient groups performed well in a test of simultaneous visual matching to sample, medicated patients (MED PD) with severe clinical symptoms were significantly impaired when a short (0-12 sec) delay was introduced. In a test of paired associates learning requiring both visual pattern and visuospatial memory, deficits in learning and memory were only evident in the severely impaired MED PD group. In contrast, in a test of spatial working memory known to be sensitive to frontal lobe damage, significant impairments were found in both groups of medicated PD patients and particularly in those patients with more severe clinical symptoms. Taken together, the results suggest that there are multiple memory impairments in PD which may differentially depend on the clinical severity of the disease.

Dopamine and depression

The dopamine hypothesis of schizophrenia and the emphasis on other neurotransmitters, most notably norepinephrine, serotonin, and acetylcholine, in the pathogenesis of depression, have focused attention away from substantial evidence implicating dopamine in affective disorders. The clinical evidence includes alterations in depressive symptoms with aging (concomitant with possible changes in dopamine metabolism), potential dopaminergic involvement in several subtypes of depression, similarities between some of the symptoms of Parkinson's disease and those of depression (including psychomotor retardation and diminished motivation), and potential dopaminergic abnormalities in seasonal mood disorder. The biochemical evidence in patients with depression derives from studies of homovanillic acid, a dopamine metabolite, indicating diminished dopamine turnover. In addition, there is a considerable amount of pharmacologic evidence regarding the efficacy of antidepressants with dopaminergic effects in the treatment of depression. We conclude that dopamine likely contributes significantly to the pathophysiology of depression. However, the role of dopamine in this syndrome must be understood in the context of existing theories involving other neurotransmitters which may act independently, and interact with dopamine and other neurochemicals, to contribute to depression.

Encoding deficits in untreated Parkinson's disease

Short-term memory deficits are prominent in untreated Parkinson's Disease (PD) and speed of central processing is known to be abnormal. To investigate the relationship between these findings, a modification of the Brown-Peterson paradigm was given to newly diagnosed, untreated patients and healthy control subjects (HCS). The PD patients were impaired under conditions of long stimulus exposure but not when study time was short. Although patients displayed deficits in immediate recall, they were more impaired at longer test delays. They achieved fewer encoding operations per unit time, resulting in a divergence of group performance with increasing duration of stimulus exposure. Performance in the PD group did not associate with motor disability, disease duration or rating of depression. These results are discussed in terms of a unifying reduced central processing deficit that is evident in PD but is independent of physical symptoms.

Monoamine metabolism in the cerebrospinal fluid in Parkinson's disease: relationship to clinical symptoms and subsequent therapeutic outcomes

We correlated monoamine concentrations in the cerebrospinal fluid from de novo (untreated) patients with Parkinson's disease with their clinical symptoms and therapeutic outcome after two years of L-dopa with/without other anti-parkinson medication. A significant correlation was found between the severity of some parkinsonian symptoms and the reduction in particular monoamines: Hoehn and Yahr's stage with dopamine, norepinephrine, and homovanillic acid: rigidity with dopamine; akinesia with dopamine and norepinephrine; freezing of gait with norepinephrine; and dementia with dopamine and homovanillic acid. Tremor had no correlations with the concentrations of the monoamines measured. Patients with dementia had a significantly increased level of epinephrine concentrations. Insufficient therapeutic responses of individual symptoms were associated with significantly decreased concentrations of particular monoamines before treatment: Hoehn and Yahr's stage with norepinephrine and epinephrine; akinesia with homovanillic acid and 5-hydroxyindoleacetic acid; and freezing of gait with dopamine, norepinephrine, homovanillic acid, and 5-hydroxyindoleacetic acid. These results suggest a significant correlation between the reduction in particular monoamines and the severity of some parkinsonian symptoms and their subsequent responses to L-dopa.