Myocardial sympathetic degeneration correlates with clinical phenotype of Parkinson's disease.

In idiopathic Parkinson's disease (PD), different clinical subtypes are distinguished due to predominant motor symptoms: a tremor-dominant type (TDT), an akinetic rigid type (ART), and a mixed type (MT). We compared myocardial sympathetic innervation, measured by MIBG scintigraphy, in different subtypes of PD at early and advanced stages of PD. We applied MIBG scintigraphy in 102 patients with PD. About 57 patients were at Hoehn and Yahr (H&Y) stage 1, 22 at H&Y stage 2, and 23 at H&Y stages 3 and 4. For quantification of myocardial MIBG uptake, the heart-to-mediastinum (H/M) count-ratio was calculated. At all H&Y stages, myocardial MIBG uptake was significantly higher in TDT patients than in ART or MT patients (P < 0.05; ANOVA). Furthermore, at each H&Y stage, myocardial MIBG uptake correlated significantly with severity of hypokinesia (P < 0.05; Spearman's correlation) and rigidity (P < 0.05), but not with severity of resting or postural tremor. The significant correlation between myocardial sympathetic degeneration and severity of hypokinesia and rigidity suggests that myocardial sympathetic degeneration and hypokinetic-rigid symptoms develop in a closely coupled manner in early as well as advanced PD. No such correlation can be found between myocardial sympathetic degeneration and parkinsonian tremor.     

Melatonin treatment potentiates neurodegeneration in a rat rotenone Parkinson's disease model

Parkinson's disease (PD) is characterized pathologically by progressive neurodegeneration of the nigrostriatal dopamine (DA) system. Currently, the cause of the disease is unknown, except for a small percentage of familial cases (<10% of total). The rat rotenone model reproduces many of the pathological features of the human disease, including apomorphine‐responsive behavioral deficits, DA depletion, loss of striatal DA terminals and nigral dopaminergic neurons, and α‐synuclein/polyubiquitin‐positive cytoplasmic inclusions reminiscent of Lewy bodies. Therefore, this model is well‐suited to examine potential neuroprotective agents. Melatonin is produced mainly by the pineal gland and is known primarily for regulating circadian rhythms. It also has potent free radical scavenging and antiinflammatory properties. Melatonin has been reported to be neuroprotective in the 6‐hydroxydopamine (6‐OHDA) and 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) models of PD. However, there are conflicting reports suggesting that melatonin does not provide neuroprotection in these models. Melatonin elicits significant functional changes in the nigrostriatal DA system that may affect 6‐OHDA and MPTP entry into cells. Therefore, rotenone is an ideal model for assessing protection, because it does not rely on the dopamine transporter uptake to exert neurotoxicity. In this study, the neuroprotective potential of melatonin in the rotenone PD model was assessed. Melatonin potentiated striatal catecholamine depletion, striatal terminal loss, and nigral DA cell loss. Indeed, melatonin alone elicited alterations in striatal catecholamine content. Our findings indicate that melatonin is not neuroprotective in the rotenone model of PD and may exacerbate neurodegeneration. © 2009 Wiley‐Liss, Inc.     

Lowered cardiac sympathetic nerve performance in response to exercise in Parkinson's disease

We examined whether cardiac sympathetic denervation influences the cardiovascular response to exercise in Parkinson's disease (PD). Sixteen patients with PD were divided into two groups, according to their cardiac uptake of ¹²³I‐metaiodobenzylguanidine (denervated group, 10 patients with heart to mediastinum (H/M) ratio < 1.7; innervated group, six patients with H/M ratio > 1.7) and compared changes in blood pressure (BP), heart rate (HR), and cardiac contractility with 13 control subjects during ergometric exercise stress. Velocity index (VI), an indicator of cardiac contractility, was measured using impedance cardiography and recorded every minute. Exercise began at a power output of 20 W for the first 2 min and increased 10 W every 2 min to a maximal intensity of 60 W. All control subjects accomplished the procedure while six patients with PD could not continue after the first minute of 50 W loading. There were no significant differences in BP or HR change between the three groups. However, a significant reduction in VI was observed from the first minute of the 30 W workload in the denervated group compared to the control group. This lowered response continued till 50 W loading and was significantly different to the innervated group at 50 W loading. No significant VI changes were observed between the control and innervated groups throughout the exercise test. Patients with PD with reduced MIBG uptake had a lowered cardiac contractility than innervated subjects during exercise, suggesting that this response represents theimpaired exercise capacity of patients with PD with cardiac sympathetic denervation. © 2010 Movement Disorder Society     

Time of loss of employment in Parkinson's disease.

We examined time to loss of employment in two U.K.-based studies of 151 and 308 patients with Parkinson's disease (PD) with onset age before 65 years. Fifty-two percent and 57% of patients had retired early due to PD, 18% and 5% of patients were unemployed, and 8% and 11% were part-time-employed. Mean age of retirement was 55.8 years compared to an average retirement age of 62 years in the U.K. population. Mean time to loss of employment was 4.9 years, ranging from a mean of 6.7 years in those with onset before age 45 to 1.7 years in those with onset after age 56, but the range was large (0-17 years). After censoring for those still working and those retiring at a normal retirement age, survival analysis revealed that 46% had stopped working after a disease duration of 5 years and 82% after 10 years with a median survival to loss of employment of 6.0 (95% CI: 5.4-6.6) years. Age of onset correlated negatively with time to loss of employment (r = -0.6; P < 0.001). There were no differences between sexes, rural vs. urban living, types of work, those living alone or with a partner, and those with and without children in their household. We conclude that Parkinson's disease leads to loss of employment on average within less than 10 years of disease onset. However, the variability of time to loss of employment is large, indicating that other factors than onset age and disease duration influence loss of patients' employment.     

Predictors of weight loss in Parkinson's disease.

The objective of this study was to examine the change of body weight (BW) among Parkinson's disease (PD) patients and controls over years and determine the predictors of weight loss among PD patients. Studies on weight loss in PD studies are cross-sectional, have a short follow-up, or lack in clinical detail. We examined the percentage of BW change over years among 49 PD patients and 78 controls. The controls were from another study on longitudinal evolution of BW and body composition in the elderly. We determined the BW, Hoehn and Yahr (HY) stage, and dyskinesia status of 49 consecutive nondemented PD patients with symptom duration of 6.1 +/- 0.7 years (mean +/- SEM) and ascertained their BW at the time of diagnosis and 2.4 +/- 0.2 years before the diagnosis from medical records. We collected data again 7.2 +/- 0.5 years after the first visit. The PD group lost 7.7% +/- 1.5% of BW over the entire symptomatic period (13.1 +/- 0.8 years), while the control group lost only 0.2% +/- 0.7% of BW over 9.9 +/- 0.1 years; weight loss was clinically significant (>5%) in 55.6% of PD patients vs. 20.5% of the controls (both P values < 0.001, adjusted for sex, baseline age, and observation period duration). PD patients lost weight in both the early and advanced phases. While worsening of parkinsonism was the most important factor, age at diagnosis, emergence of visual hallucinations, and possibly dementia were also associated with weight loss. We demonstrated significant weight loss in PD patients compared to controls over approximately 1 decade. Neurodegeneration involving both motor and nonmotor systems may be associated with weight loss in PD.     

Deep brain stimulation exacerbates hypokinetic dysarthria in a rat model of Parkinson's disease

Motor symptoms of Parkinson's disease (PD) follow the degeneration of dopaminergic neurons in the substantia nigra pars compacta. Deep brain stimulation (DBS) treats some parkinsonian symptoms, such as tremor, rigidity, and bradykinesia, but may worsen certain medial motor symptoms, including hypokinetic dysarthria. The mechanisms by which DBS exacerbates dysarthria while improving other symptoms are unclear and difficult to study in human patients. This study proposes an animal model of DBS‐exacerbated dysarthria. We use the unilateral, 6‐hydroxydopamine (6‐OHDA) rat model of PD to test the hypothesis that DBS exacerbates quantifiable aspects of vocalization. Mating calls were recorded from sexually experienced male rats under healthy and parkinsonian conditions and during DBS of the subthalamic nucleus. Relative to healthy rats, parkinsonian animals made fewer calls with shorter and less complex vocalizations. In the parkinsonian rats, putatively therapeutic DBS further reduced call frequency, duration, and complexity. The individual utterances of parkinsonian rats spanned a greater bandwidth than those of healthy rats, potentially reducing the effectiveness of the vocal signal. This utterance bandwidth was further increased by DBS. We propose that the parkinsonism‐associated changes in call frequency, duration, complexity, and dynamic range combine to constitute a rat analog of parkinsonian dysarthria. Because DBS exacerbates the parkinsonism‐associated changes in each of these metrics, the subthalamic stimulated 6‐OHDA rat is a good model of DBS‐induced hypokinetic dysarthria in PD. This model will help researchers examine how DBS alleviates many motor symptoms of PD while exacerbating parkinsonian speech deficits that can greatly diminish patient quality of life. © 2015 Wiley Periodicals, Inc.     

Behavioral and structural effects of unilateral intrastriatal injections of botulinum neurotoxin a in the rat model of Parkinson's disease

Botulinum neurotoxin (BoNT) inhibits the release of acetylcholine from presynaptic vesicles through its proteinase activity cleaving the SNARE complex. Parkinson's disease (PD) is associated with locally increased cholinergic activity in the striatum. Therefore, the present study investigates the effect of unilateral intrastriatal BoNT‐A injection in naïve rats on striatal morphology; i.e., the total number of Nissl‐stained neurons and the volume of caudate‐putamen (CPu) were estimated. Furthermore, stainings for markers of gliosis (glial fibrillary acidic protein) and microglia (Iba1) were performed. In addition, the potential beneficial effects of a unilateral intrastriatal injection of BoNT‐A on motor activity in the rat model of hemi‐PD were evaluated. Hemi‐PD was induced by unilateral injection of 6‐hydroxydopamine (6‐OHDA) into the right medial forebrain bundle. Six weeks later, rats received an ipsilateral intrastriatal injection of BoNT‐A. Behaviorally, motor performance was tested. The total number of CPu neurons and the striatal volume were not significantly different between the BoNT‐A‐injected right and the intact left hemispheres of naïve rats. In hemi‐PD rats, intrastriatal BoNT‐A abolished apomorphine‐induced rotations, increased amphetamine‐induced rotations, and tended to improve left forelimb usage. Forced motor function in the accelerod test was not significantly changed by BoNT‐A, and open field activity was also unaltered compared with sham treatment. Thus, intrastriatal BoNT‐A affects spontaneous motor activity of hemi‐PD rats to a minor degree compared with drug‐induced motor function. In the future, tests assessing the cognitive and emotional performance should be performed to ascertain finally the potential therapeutic usefulness of intrastriatal BoNT‐A for PD. © 2013 Wiley Periodicals, Inc.     

Cognitive profile of Parkinson's disease patients: a comparative study between early-onset and late-onset Parkinson's disease

Aim: To investigate the influence of onset age on the occurrence and progression of cognitive dysfunction using neuropsychological tests and the electrophysiological component P300 in both early-onset Parkinson's disease (EOPD) and late-onset Parkinson's disease (LOPD) patients. Methods: A cohort of 76 EOPD patients and 166 LOPD patients was recruited for this study. Demographic information and clinical features, including age, disease duration, education level, family history, the Unified Parkinson's Disease Rating Scale, the Hoehn and Yahr stage, and depression scores were documented for each patient. The Mini-Mental State Examination, Montreal Cognitive Assessment (MoCA), Wechsler Adult Intelligence Scale – Revised, Chinese version (WAIS-RC) and Wechsler Memory Scale – Revised, Chinese version (WMS-RC) were used. In addition, P300 was also examined to assess cognitive function. Results: Although EOPD patients had longer disease duration, their cognitive dysfunction progressed more slowly. The MoCA tests revealed that EOPD patients had higher scores in visuospatial function, attention, delayed recall, and orientation than the LOPD patients. The difference between the two groups on the WMS-RC test did not reach significance, whereas the scores in executive function, visuospatial function and attention as measured on the WAIS-RC test were significantly lower in the LOPD group. In addition, P300 latencies were markedly delayed and P300 amplitudes were reduced in the LOPD group. Conclusions: The current findings demonstrated that cognitive dysfunction progressed more slowly in the EOPD group. Although the LOPD patients exhibited shorter disease durations, their cognitive abilities, including executive function, visuospatial function and attention, may have been impaired.     

Visual symptoms in Parkinson's disease and Parkinson's disease dementia

Visual symptoms are common in PD and PD dementia and include difficulty reading, double vision, illusions, feelings of presence and passage, and complex visual hallucinations. Despite the established prognostic implications of complex visual hallucinations, the interaction between cognitive decline, visual impairment, and other visual symptoms remains poorly understood. Our aim was to characterize the spectrum of visual symptomatology in PD and examine clinical predictors for their occurrence. Sixty-four subjects with PD, 26 with PD dementia, and 32 age-matched controls were assessed for visual symptoms, cognitive impairment, and ocular pathology. Complex visual hallucinations were common in PD (17%) and PD dementia (89%). Dementia subjects reported illusions (65%) and presence (62%) more frequently than PD or control subjects, but the frequency of passage hallucinations in PD and PD dementia groups was equivalent (48% versus 69%, respectively; P = 0.102). Visual acuity and contrast sensitivity was impaired in parkinsonian subjects, with disease severity and age emerging as the key predictors. Regression analysis identified a variety of factors independently predictive of complex visual hallucinations (e.g., dementia, visual acuity, and depression), illusions (e.g., excessive daytime somnolence and disease severity), and presence (e.g., rapid eye movement sleep behavior disorder and excessive daytime somnolence). Our results demonstrate that different "hallucinatory" experiences in PD do not necessarily share common disease predictors and may, therefore, be driven by different pathophysiological mechanisms. If confirmed, such a finding will have important implications for future studies of visual symptoms and cognitive decline in PD and PD dementia.     

Cardiac sympathetic degeneration correlates with olfactory function in Parkinson's disease

Autonomic and olfactory dysfunctions are considered markers for preclinical diagnosis in Parkinson's disease (PD), because pathological changes in these systems can start before motor symptoms develop. We investigated whether cardiac sympathetic function and olfactory function are associated in PD. Participants comprised 40 nondemented patients with idiopathic PD, and age‐matched controls. Cardiac sympathetic function was evaluated by ¹²³ I‐metaiodobenzylguanidine (MIBG) uptake, in terms of the heart to mediastinum (H/M) ratio in both early and delayed images, and the washout rate (WR). Olfactory function was evaluated using the Odor Stick Identification Test for Japanese, which evaluates the detection of 12 odorants familiar to Japanese participants. Smell identification scores were significantly lower (P < 0.001) in patients with PD than in controls. Smell identification scores correlated positively with early (P < 0.05) and delayed H/M ratios (P < 0.01), and inversely with the WR (P < 0.005) especially in patients with early PD (below 5 years of the start of motor symptoms), whereas smell identification scores did not correlate with any parameters of MIBG in the advanced PD (above 5 years of the start of motor symptoms). There was no correlation between motor symptom scores and smell identification scores, H/M ratios, or WR. The results suggest that the cardiac sympathetic nervous system might degenerate in parallel with the olfactory system in patients with early PD, and that these two systems might degenerate at a different rate of speed in advanced PD. © 2010 Movement Disorder Society     

Hippocampal volume and white matter disease in the prediction of dementia in Parkinson's disease

BackgroundLongitudinal neuroimaging studies could provide insights into pathophysiology of cognitive impairment in PD. We examined the role of hippocampal atrophy and cerebral white matter disease as risk factors for mild cognitive impairment and dementia in PD.MethodsProspective longitudinal study of patients with mild PD in a tertiary neurology center. All subjects underwent baseline MRI brain and had baseline and 6 monthly cognitive evaluations. Cognitive impairment was diagnosed based on the Movement Disorder Society Criteria. The predictive role of hippocampal volume and white matter hyperintensity at baseline on progression of cognitive impairment was studied.Results97 subjects with mean age 65.3 years, mean education of 10.3 years and mean Hoehn & Yahr of 1.9 were studied. Over 2 years, 16 subjects developed mild cognitive impairment and 8 subjects with mild cognitive impairment progressed to dementia. After adjusting for age and vascular risk factors, hippocampal volume was a significant predictor for mild cognitive impairment (OR 7.05, CI 1.5–34.1; p = 0.015) and dementia (OR 7.03, CI 2.39–25.2; p = 0.001). With Cox regression, hippocampal volume was a significant predictor for “time to cognitive impairment” (HR 7.67; CI 3.47–16.95, p < 0.001). Difference between survival curves based on volume of white matter hyperintensity in predicting “time to mild cognitive impairment” was significant (p = 0.0295).ConclusionsHippocampal volume is a major factor predicting the development of mild cognitive impairment and dementia in PD. White matter hyperintensity also contributes to the longitudinal cognitive status in PD.     

Perception of heaviness in Parkinson's disease

The present study investigated whether a specific aspect of proprioception, the sense of heaviness or weight is affected in PD. We determined detection thresholds for the perception of a gravito‐inertial load in 10 PD patients and 11 age‐matched control subjects. A gradually increasing weight was applied to the index finger by means of two slings of different width (low vs. high skin pressure). For the controls, mean detection thresholds were 31.3 g at skin high pressure and 33.0 g under low pressure. PD patients revealed significantly higher thresholds than the control group in both pressure conditions (mean high pressure,47.7 g; mean low pressure, 52.3 g; group effect, P = 0.001). Thresholds of PD patients tended to increase with disease severity as measured by the Unified Parkinson's Disease Rating Scale Motor score (r = 0.55) but did not correlate significantly with levodopa equivalent dosage. The results demonstrate that the perception of heaviness or weight is already affected in the early stages of PD. These findings underline the growing evidence that proprioceptive and possibly haptic dysfunction is a common feature of PD. © 2006 Movement Disorder Society     

Cardiovascular effects of methamphetamine in Parkinson's disease patients.

Cardiovascular responses after intravenous methamphetamine were assessed in 11 Parkinson's disease (PD) patients. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and electrocardiogram (ECG) were monitored for 103 minutes. After methamphetamine administration, SBP and DBP increased significantly in both PD and normal controls whereas placebo had no effect. In PD patients, however, the duration of SBP and DBP responses to methamphetamine and the maximum increase from baseline was attenuated compared with the controls. A significant correlation was found between individual BP responsiveness and the Unified Parkinson's Disease Rating Scale (UPDRS) motor score. These findings suggest that in PD there is impairment of catecholamine release from peripheral sympathetic presynaptic terminals, which correlates with motor impairment.     

Increase in body weight after pramipexole treatment in Parkinson's disease.

Body weight changes occur during the clinical course of Parkinson's disease (PD) and with surgical treatment, but the effect of dopaminergic treatment on weight is unknown. Body mass index (BMI), Hamilton depression scale score (HDS), and Unified Parkinson's Disease Rating Scale III (UPRS-III) were measured before and 3 months after starting pramipexole in 28 PD patients. Pramipexole produced a significant weight increase, as well as motor and mood improvement (P <0.001). HDS and BMI changes were mildly related (P = 0.05). A direct effect of pramipexole on limbic D(3) receptors involved in the control of feeding may be responsible for weight gain in PD.     

Timing matters: Otological symptoms and Parkinson's disease

IntroductionOtological symptoms contribute to the disability of established Parkinson's disease (PD). We sought to evaluate whether prodromal onset may affect PD progression.MethodsA retrospective cohort design was used to compare time to advanced disease, defined as a Hoehn & Yahr stage ≥3 in consecutive PD patients with history of auditory and/or vestibular symptoms appearing before versus after PD onset. Time from PD onset to H&Y ≥ 3 was determined using Cox proportional hazards, with adjusted results summarized as hazards ratio (HR).ResultsAfter adjusting for age at PD onset, there was a lower risk of progression to advanced disease in patients with prodromal otological symptoms compared to those with otological symptoms after PD onset (HR = 0.34; 95%CI: 0.15–0.75, p = 0.008). This association remained significant after adjusting for age at PD onset and MDS-UPDRS III (HR = 0.25; 95% CI: 0.10–0.63, p = 0.003) and propensity score-adjusted analysis (HR = 0.46; 95% CI: 0.24–0.91, p = 0.025).ConclusionProdromal otological symptoms might be associated with a reduced risk of motor progression in PD.     

Intestinal dysmotility and enteric neurochemical changes in a Parkinson's disease rat model

Gastrointestinal disorders, constipation in particular, are the most common non-motor dysfunctions affecting Parkinson's disease (PD) patients. We have previously reported that rats bearing unilateral nigrostriatal lesion caused by 6-hydroxydopamine (6-OHDA) stereotaxic injection develop severe constipation together with a region-specific decrease of neuronal nitric oxide synthase (nNOS) in enteric neurons of the lower intestinal tract. Here, we extend these observations on other enteric neuronal subpopulations, investigating also the propulsive activity of isolated colonic specimens. Four weeks post 6-OHDA injection, lesioned rats showed a significant increase of vasoactive intestinal polypeptide (VIP) concomitant with the reduced expression of nNOS in the myenteric plexus of distal ileum and proximal colon; in particular VIP increased in a subpopulation of neurons actively expressing nNOS. On the other hand, choline acetyltransferase (ChAT) was not modified in any of the intestinal segments analyzed. Interestingly, we found a reduced expression of dopamine receptor type 2 (D2R) in proximal (-66.8%) and distal (-54.5%) colon, together with reduced peristalsis efficiency (decrease in intraluminal pressure and frequency of peristaltic events) in the 6-OHDA-lesioned rats. The selective depletion of dopaminergic nigrostriatal neurons is associated with changes in the expression of enteric inhibitory neurotransmitters, as well as of the D2R in intestinal specific regions. Moreover, 6-OHDA-lesioned rats demonstrated altered colon propulsive activity referable to the D2R decrease. Our findings unveil subtle mechanisms underlying the enteric neurochemical plasticity events evoked by disruption of the normal brain-gut cross-talk, giving a peculiar point of view on the pathophysiology of the severe constipation that frequently affects PD patients.     

Hyperhidrosis in Parkinson's disease.

We studied the sudomotor skin response (SSR) in patients with Parkinson's disease with and without symptomatic hyperhidrosis. The study was carried out in 13 patients who complained of excessive sweating and in 37 patients who did not have excessive sweating. Patients were matched for age, sex, degree of impairment, duration of the disease, and number and severity of autonomic disturbances. Excessive sweating involved mainly the face, head, and trunk. The SSR was recorded from the palm of the hands to electrical stimulation of the median nerve at the wrist. We analyzed onset latency, peak to peak amplitude, and waveform. Patients with hyperhidrosis had more often absent responses (chi(2) = 5.292; P = 0.021), their responses were of lower mean amplitude (analysis of variance [ANOVA]; F[2,101] = 11.678; P < 0.001), and they had a reduced number of responses with a predominantly negative component (chi(2) = 8.493; P = 0.004) than patients who did not complain of sweating disturbances. Our results indicate that excessive sweating in Parkinson's disease concurs with decreased activation of sweat glands in the palms of the hands and suggests that axial hyperhidrosis could be a compensatory phenomenon for reduced sympathetic function in the extremities.