Asymmetry of basal ganglia glucose metabolism and dopa responsiveness in parkinsonism

Exploring Nonmotor Neuropsychiatric Manifestations of Parkinson Disease in a Comprehensive Care Setting

Parkinson disease (PD) is a debilitating neurological condition that includes both motor symptoms and nonmotor symptoms (NMS). Psychiatric complaints comprise NMS and are collectively referred to as neuropsychiatric manifestations. Common findings include atypical depressive symptoms, anxiety, psychosis, impulse control disorder, deterioration of cognition, and sleep disturbances. Quality of life (QoL) of patients suffering from NMS is greatly impacted and many times can be more debilitating than motor symptoms of PD. We expand on knowledge gained from treatment models within a comprehensive care model that incorporates multidisciplinary specialists working alongside psychiatrists to treat PD. Insight into background, clinical presentations, and treatment options for patients suffering from neuropsychiatric manifestations of PD are discussed. Identifying symptoms early can help improve QoL, provide early symptom relief, and can assist tailoring treatment plans that limit neuropsychiatric manifestations.

Lateralisation in Parkinson disease

Asymmetry of dopaminergic neurodegeneration and subsequent lateralisation of motor symptoms are distinctive features of Parkinson's disease compared to other forms of neurodegenerative or symptomatic parkinsonism. Even 200 years after the first description of the disease, the underlying causes for this striking clinicopathological feature are not yet fully understood. There is increasing evidence that lateralisation of disease is due to a complex interplay of hereditary and environmental factors that are reflected not only in the concept of dominant hemispheres and handedness but also in specific susceptibilities of neuronal subpopulations within the substantia nigra. As a consequence, not only the obvious lateralisation of motor symptoms occurs but also patterns of associated non-motor signs are defined, which include cognitive functions, sleep behaviour or olfaction. Better understanding of the mechanisms contributing to lateralisation of neurodegeneration and the resulting patterns of clinical phenotypes based on bilateral post-mortem brain analyses and clinical studies focusing on right/left hemispheric symptom origin will help to develop more targeted therapeutic approaches, taking into account subtypes of PD as a heterogeneous disorder.

Evidence for cross-hemispheric preconditioning in experimental Parkinson's disease

Dopamine loss and motor deficits in Parkinson's disease typically commence unilaterally and remain asymmetric for many years, raising the possibility that endogenous defenses slow the cross-hemispheric transmission of pathology. It is well-established that the biological response to subtoxic stress prepares cells to survive subsequent toxic challenges, a phenomenon known as preconditioning, tolerance, or stress adaptation. Here we demonstrate that unilateral striatal infusions of the oxidative toxicant 6-hydroxydopamine (6-OHDA) precondition the contralateral nigrostriatal pathway against the toxicity of a second 6-OHDA infusion in the opposite hemisphere. 6-OHDA-induced loss of dopaminergic terminals in the contralateral striatum was ablated by cross-hemispheric preconditioning, as shown by two independent markers of the dopaminergic phenotype, each measured by two blinded observers. Similarly, loss of dopaminergic somata in the contralateral substantia nigra was also abolished, according to two blinded measurements. Motor asymmetries in floor landings, forelimb contacts with a wall, and spontaneous turning behavior were consistent with these histological observations. Unilateral 6-OHDA infusions increased phosphorylation of the kinase ERK2 and expression of the antioxidant enzyme CuZn superoxide dismutase in both striata, consistent with our previous mechanistic work showing that these two proteins mediate preconditioning in dopaminergic cells. These findings support the existence of cross-hemispheric preconditioning in Parkinson's disease and suggest that dopaminergic neurons mount impressive natural defenses, despite their reputation as being vulnerable to oxidative injury. If these results generalize to humans, Parkinson's pathology may progress slowly and asymmetrically because exposure to a disease-precipitating insult induces bilateral upregulation of endogenous defenses and elicits cross-hemispheric preconditioning.

Cognitive Behavior Therapy for Anxiety in Parkinson's Disease: Outcomes for Patients and Caregivers

OBJECTIVE

Anxiety negatively impacts the quality of life of Parkinson's disease (PD) patients and caregivers. Despite high prevalence, there is a paucity of trials investigating effective treatments for anxiety in PD. This uncontrolled study investigated the use of a manualized and tailored Cognitive Behavior Therapy (CBT) for anxiety in PD.

METHODS

Participants completed 6 weekly CBT sessions. Pre-, post- and follow-up (3 and 6 months) assessments were made. Change in outcomes were analysed using t-tests and Reliability Change Index. Of 17 PD patients who agreed to CBT, 12 completed the intervention.

RESULTS

This study showed a significant reduction in Hamilton Anxiety Rating Scale scores in PD immediately post CBT (t(11) = 3.59, p < .01), maintained at 3-month (t(8) = 2.83, p = .02) and 6-month (t(7) = 2.07, p = .04) follow-up. A reduction in caregiver burden (t(11) = 2.68, p = .03) was observed post intervention. Improvements in motor disability (t(11) = 2.41, p = .04) and cognitive scores (t(11) = -2.92, p = .01) were also observed post intervention and at follow-up.

CONCLUSIONS

Tailored CBT can be used to treat anxiety in PD.

CLINICAL IMPLICATIONS

This study provides preliminary evidence suggesting that tailored CBT reduces anxiety in PD with persisting benefits, and lowers caregiver burden.

Anxiety in Parkinson's disease: identification and management

Anxiety disturbances are recognized as common psychiatric comorbidities in Parkinson's disease (PD) and contribute to significant impairments in areas of cognitive, functional, motor and social performance. Anxiety in PD results in reduced quality of life, higher levels of care dependency and increased caregiver burden. Surprisingly, there is a paucity of treatment data. In one randomized, controlled study, bromazepam was found to be effective for anxiety in PD. However, usage of benzodiazepines in the PD population is limited by potential risk of confusion and falls. There are no controlled studies of selective serotonin reuptake inhibitors (SSRIs) for anxiety in PD. However, results from uncontrolled studies suggest that SSRIs are effective for anxiety in PD, although in these studies anxiety outcomes were secondary. This review underscores that, given the high prevalence of anxiety disturbances in PD, there is a significant paucity of treatment data for this population. Additional studies are warranted. In the meantime, clinicians should rely on empiric assessments of known risks and putative benefits to guide treatment decisions. Cognitive and behavioral therapies (with or without pharmacotherapy) have demonstrated efficacy and warrant consideration. When feasible, a targeted and individualized multimodal approach utilizing psychotherapeutic interventions along with pharmacologic therapies should be considered.

Apathy in patients with Parkinson disease as a function of side of onset

BACKGROUND

In previous studies among patients with Parkinson disease (PD) who were administered the Apathy Evaluation Scale (AES), between 12% and 51% evidenced clinically significant apathy. Although apathy is a risk factor for dementia, its causes and clinical correlates have not been adequately studied. In particular, side of onset of disease, though a likely predictor of apathy and dementia, has not been thoroughly investigated.

METHODS

A total of 30 mid-stage patients with PD and 35 community-dwelling elderly control patients (CPs) were administered the AES (self version) along with a battery of cognitive and neuropsychiatric assessments. Persons close to patients with PD and CPs completed the AES--other (informant) version about the patient or CP. Multiple linear regression analysis examined predictors of apathy severity after controlling for mood, levodopa dosage equivalents (LDEs), gender, age, and disease severity (Hoehn--Yahr [H-Y] stage).

RESULTS

Patients with right-onset disease more frequently exhibited apathy and evidenced significantly higher total AES scores than left-onset patients with PD or CPs (P < .03). Of all the patients, 42% with right-onset PD versus 11.1% of the patients with left-onset PD exhibited clinically significant levels of apathy. There were no differences for self versus informant scores for right-onset patients with PD. The AES scores were not correlated with depression, stress, anxiety, LDEs, gender, age, and H-Y stage. There were no gender differences for any AES variables.

CONCLUSION

Clinically significant levels of apathy are much more likely to occur in patients with right-onset disease. These patients may be at greater risk of PD-related dementia.

The role of PET imaging in the management of patients with central nervous system disorders

PET will continue to play a critical role in both clinical and research applications with regard to CNS disorders. PET is useful in the initial diagnosis of patients presenting with CNS symptoms and can help clinicians determine the best course of therapy. PET studies can also be useful for studying the response to therapy. From the research perspective, the various neurotransmitter and other molecular tracers currently available or in development will provide substantial information about pathophysiologic process in the brain. As such applications become more widely tested, their introduction into the clinical arena will further advance the use of PET imaging in the evaluation and management of CNS disorders.

Cerebellar metabolic symmetry in essential tremor studied with1H magnetic resonance spectroscopic imaging: Implications for disease pathology

The pathological basis for essential tremor (ET) is not known; however, metabolic changes in the cerebellum can be observed in positron emission tomography (PET) and (1)H magnetic resonance spectroscopic imaging (MRSI) studies. Tremor is relatively symmetric in ET, suggesting that underlying metabolic changes could be also symmetric. The degree of metabolic asymmetry in the cerebellum, however, has not yet been studied in ET, and knowledge about distribution and laterality of metabolic changes might shed some light on basic disease mechanisms. We measured brain metabolism (N-acetylaspartate[NAA]/creatine [tCR]) to obtain an asymmetry index for cerebellar cortical metabolism ET patients compared with that in controls. This index, a percentage, was calculated as [absolute value (value right - value left)]/(value right + value left) x 100. Multislice (1)H MRSI data were acquired for 20 patients and 11 controls. In ET patients, mean right and left cerebellar cortical NAA/tCR values were 1.61 +/- 0.42 and 1.55 +/- 0.38, respectively, compared with 1.81 +/- 0.62 and 1.87 +/- 0.49 in controls. The difference between right and left cerebellar cortical NAA/tCR was also calculated for each subject. In ET patients, the mean right-left difference was 0.14 +/- 0.11, compared with 0.32 +/- 0.27 in controls (P = 0.016). The mean cerebellar cortical asymmetry index was low in ET (8.8 +/- 6.1%), one-half of that in controls (17.0 +/- 13.7%, P = 0.027). These data suggest that pathological lesions in ET patients, which remain elusive, might be distributed similarly in each cerebellar cortex. Postmortem studies are needed to confirm these preliminary imaging results.

The role of positron emission tomography imaging in movement disorders

PET imaging provides the means to study neurochemical, hemodynamic, or metabolic processes that underlie movement disorders in vivo. Because the extent of presynaptic nigrostriatal dopaminergic denervation can be quantified in PD even at an early or preclinical stage of the disease, PET imaging may allow the selection of at-risk subjects for neuroprotective intervention trials. These techniques may also provide markers to follow progression of disease or evaluate the effects of neurorestorative interventions in patients who have more advanced disease. PET is expected to play an increasing role in the selection of patients who have PD for deep brain stimulation. Dopaminergic studies may have a limited clinical role in the diagnosis of patients who have symptoms that suggestive of PD yet do not respond to typical dopaminergic drugs, such as patients who have vascular parkinsonism or ET with mild resting tremor who may have normal dopaminergic innervation. The differential diagnosis between PD and multiple system atrophy, progressive supranuclear palsy, or corticobasal degeneration is not yet clearly established by PET, but combined pre- and postsynaptic dopaminergic imaging may be able to distinguish early idiopathic PD from atypical parkinsonian disorders, in general. Huntington's chorea is characterized by more prominent striatal dopamine receptor loss, whereas nigrostriatal denervation is present to a lesser degree. Patients who have TS may have enhanced synaptic dopamine release in the putamen. Functional imaging studies have generally failed to demonstrate nigrostriatal denervation in essential tremor or idiopathic dystonia. Studies have shown striatal dopamine receptor loss in selected subtypes of dystonic patients. In conclusion, it is expected that PET will help us to better understand the pathophysiology of movement disorders, increase the diagnostic accuracy, allow preclinical diagnosis, monitor disease progression, and evaluate the efficacy of therapeutic agents. Pharmacologic radioligand displacement studies and the development of new nondopaminergic ligands may further aid in the unraveling of cerebral mechanisms that underlie movement disorders.

Secondary nonresponsiveness to new bulk botulinum toxin A (BCB2024)

We report on a patient with cranio-cervical dystonia injected with the new, lower protein formulation of botulinum toxin A who developed secondary resistance to this toxin. Subsequent injections with botulinum toxin B provided substantial reduction of blepharospasm. This is the first reported case of secondary resistance to the new preparation of botulinum toxin A.

Paradoxical response to apomorphine in a case of atypical parkinsonism

We describe a patient with clinical signs of parkinsonism showing a paradoxical response to apomorphine injection. We discuss possible pathogenetic mechanisms with regard to the literature and suggest the diagnosis of a striatonigral degeneration at an early stage.

Determination of regional cerebral function with FDG-PET imaging in neuropsychiatric disorders

Functional brain imaging using 18F fluorodeoxyglucose (FDG) and positron emission tomography (PET) has greatly enhanced our understanding of brain function both in normal conditions as well as in a wide variety of neuropsychiatric disorders. We review the uses of FDG PET in the diagnosis, management, and follow-up of patients with neuropsychiatric disorders. This article will also explore what FDG-PET imaging has revealed in these neuropsychiatric disorders and how these findings relate to both research and clinical applications.

Normalization of markers for dopamine innervation in striatum of MPTP-lesioned miniature pigs with intrastriatal grafts

As part of the DaNeX study, the uptake and binding of several positron emitting tracers was recorded in brain of healthy Göttingen minipigs, in minipigs with a syndrome of parkinsonism due to MPTP intoxication, and in parkinsonian minipigs which had received intrastriatal grafts of mesencephalic neurons from fetal pigs. The specific binding of [11C]NS 2214 to catecholamine uptake sites was reduced by two thirds in striatum of the intoxicated animals, while the rate constant for the decarboxylation of [18F]fluorodopa was reduced by 50% in the intoxicated animals. Several months after grafting, both pre-synaptic markers of dopamine fibres were normal in striatum. Dopamine depletion or grafting were without effect on the cerebral perfusion rate, measured with [15O]-water, did not alter the rate of oxygen metabolism (CMRO2) in brain, and did not alter the binding potential of tracers for dopamine D1 or D2 receptors in pig striatum. However, the grafting was associated with a local increase in the binding of [11C]PK 11195, a tracer for reactive gliosis, suggesting that an immunological reaction occurs at the site of graft, which might potentially have reduced the graft patency. However, this apparent immunological response did not preclude the re-establishment of normal [18F]fluorodopa and [11C]NS 2214 uptake in the allografted striatum.

FDG positron emission tomography in diffuse Lewy body disease: a case report

Lewy body disease is a clinicopathologic condition that includes Parkinson's disease at one end and diffuse Lewy body disease at the other hand. The latter is often associated with progressive cognitive deterioration, levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, and visual and auditory hallucinations. In addition, it can be a familial disease. Clinical and positron emission tomographic findings are described in a patient with atypical dementia and movement disorder and a pathologically proved diagnosis of diffuse Lewy body disease.