María José Martí

Rapid-eye-movement sleep behaviour disorder as an early marker for a neurodegenerative disorder: a descriptive study

BACKGROUND Rapid-eye-movement (REM) sleep behaviour disorder (RBD) is a parasomnia characterised by dream-enacting behaviours related to unpleasant dreams and loss of muscle atonia during REM sleep. RBD may be idiopathic or associated with neurological disease. Available data suggest that in some cases RBD might be the initial manifestation of a neurodegenerative disease. We sought to determine the frequency and nature of neurological disorders developing in patients diagnosed with idiopathic RBD at our sleep centre. METHODS We retrospectively assessed 44 consecutive patients (39 men and five women with a mean age of 74 years), with at least 2 years of clinical follow-up after a diagnosis of idiopathic RBD, through a detailed clinical history, complete neurological examination, rating scales of parkinsonism, and neuropsychological tests. FINDINGS 20 (45%) patients developed a neurological disorder after a mean of 11.5 years from the reported onset of RBD and a mean follow-up of 5.1 years from the diagnosis of idiopathic RBD at our sleep centre. Emerging disorders were Parkinsons disease in nine patients, dementia with Lewy bodies in six, multiple system atrophy with predominant cerebellar syndrome in one, and mild cognitive impairment in four in whom visuospatial dysfunction was prominent. Patients with longer clinical follow-up developed a neurological disease (OR 1.512, 95% CI 1.105-2.069; p=0.010). INTERPRETATION Our study indicates that in people presenting to sleep centres, RBD often antedates the development of a neurodegenerative disorder. Close follow-up of patients with idiopathic RBD could enable early detection of neurodegenerative disease. This finding may be of great interest when early effective treatment strategies and neuroprotective drugs become available.

Characteristics of idiopathic REM sleep behavior disorder and that associated with MSA and PD

Objective: To compare the clinical and video-polysomnographic (VPSG) characteristics of idiopathic REM sleep behavior disorder (RBD) vs the RBD seen in multiple system atrophy (MSA) and Parkinson disease (PD). Methods: Clinical features and VPSG measures were evaluated in 110 consecutive nondemented subjects (26 MSA, 45 PD, and 39 idiopathic RBD) free of psychoactive medications referred for suspected RBD to our sleep unit over a 5-year period, with extended follow-up (mean 26.9 ± 21.3 months). Results: Across the three groups studied, logistic regression analysis demonstrated that there were no differences in the quality of RBD symptoms (e.g., nature of unpleasant dream recall or behaviors witnessed by bed partners), most PSG variables, abnormal behaviors captured by VPSG, and clinical response to clonazepam. When compared to subjects with PD, however, patients with MSA had a significantly shorter duration of disease, a higher REM sleep without atonia percentage, a greater periodic leg movement index, and less total sleep time. Subjects with idiopathic RBD, as compared to those with either MSA or PD, were more often male, had greater self-reported clinical RBD severity, and were more often aware of their abnormal sleep behaviors. Conclusions: REM sleep behavior disorder (RBD)-related symptoms and neurophysiologic features are qualitatively similar in RBD subjects with the idiopathic form, multiple system atrophy (MSA), and Parkinson disease (PD). Polysomnographic abnormalities associated with RBD in the setting of MSA are greater than in PD, suggesting a more severe dysfunction in the structures that modulate REM sleep.

Cognitive dysfunction and dementia in Parkinson disease.

Impairment in different cognitive domains such as executive functions, language, memory, and visuospatial skills occurs frequently in Parkinson disease (PD) even in the early stages of the disease. Although frank dementia (Parkinson disease dementia, PDD) is less frequent, risk for developing dementia is two to six times greater than the prevalence rate in general population and it increases in relation to disease duration. Clinically, dementia in PD is characterized by uninsidious onset and slowly progressive cognitive decline, with a predominant dysexecutive syndrome accompanied frequently by a variety of behavioral symptoms such as hallucinations, depression, anxiety, and excessive daytime sleepiness. Although the exact pathophysiology and neurobiological basis of PDD is not known, dementia in PD probably develops as a result of progressive involvement of subcortical and cortical structures by Lewy‐type pathology and associated Alzheimer‐like histological changes. Dysfunction of different monoamine transmitter has also been implicated in the cognitive deterioration of PD but reduced cholinergic activity in the cortex is thought to account for the strongest mechanism in the development of dementia. Recent evidence suggests that cholinesterase inhibitors are effective in the treatment of dementia and accompanying behavioral symptoms in PD.

The Onset of Nonmotor Symptoms in Parkinson's disease (The ONSET PD Study)

Nonmotor symptoms (NMS) in Parkinsons disease (PD) can precede onset of motor symptoms. Relationship between premotor symptoms onset and motor features is limited. Our aim is to describe the presence and perceived onset of NMS in PD as well as their possible association with motor phenotype. Presence and onset of NMS were assessed by a custom‐made questionnaire in 109 newly diagnosed untreated PD patients and 107 controls from 11 Spanish and Austrian centers. Seventeen of thirty‐one NMS were more common in patients than controls (P < 0.05). They were usually mild and frequently reported to occur at different time‐spans before motor symptoms. Anhedonia, apathy, memory complaints, and inattention occurred more frequently during the 2‐year premotor period. Those reported more frequently in the 2‐ to 10‐year premotor period were smell loss, mood disturbances, taste loss, excessive sweating, fatigue, and pain. Constipation, dream‐enacting behavior, excessive daytime sleepiness, and postprandial fullness were frequently perceived more than 10 years before motor symptoms. No correlation between NMS burden and motor severity, age, or gender was observed. NMS associated in four clusters: rapid eye movement sleep behavior disorder symptoms‐constipation, cognition‐related, mood‐related, and sensory clusters. No cluster was associated with a specific motor phenotype or severity. NMS are common in early unmedicated PD and frequently reported to occur in the premotor period. They are generally mild, but a patient subgroup showed high NMS burden mainly resulting from cognition‐related symptoms. Certain NMS when present at the time of assessment or in the premotor stage, either alone or in combination, allowed discriminating PD from controls.

Neurophysiologic study of central pain in patients with Parkinson disease

Background: Patients with Parkinson disease (PD) may present with various types of pain. In some instances, no cause can be identified and pain is considered a primary disorder (primary central pain [PCP]). We hypothesized that PCP in patients with PD (PD-PCP) may be due to a dysfunction of pain pathways or the processing of pain inputs in the CNS. Methods: We carried out a psychophysical and neurophysiologic study in 9 patients with PD-PCP, 9 patients with PD without pain (PD-NoP), and 9 healthy control subjects. We assessed the clinical characteristics of pain, performed quantitative sensory testing with thermal probes, and recorded laser-evoked potentials (LEPs) and laser-induced sudomotor skin responses (l-SSRs) in “off” and “on” conditions. Results: In “off” condition, patients with PD-PCP had lower heat pain and laser pinprick thresholds, higher LEP amplitudes, and less habituation of the l-SSR in comparison with PD-NoP patients and control subjects. Abnormalities were more marked in the most affected side. In “on” condition, psychophysical and neurophysiologic differences disappeared or were significantly attenuated. Conclusion: Conduction along peripheral and central pain pathways is normal in patients with Parkinson disease with or without primary central pain. However, apart from signs of hyperalgesia, our patients exhibited lack of habituation of sympathetic sudomotor responses to repetitive pain stimuli, suggesting an abnormal control of the effects of pain inputs on autonomic centers. Abnormalities were attenuated by l-dopa, suggesting that the dysfunction may occur in dopamine-dependent centers regulating both autonomic function and inhibitory modulation of pain inputs.

Cerebrospinal tau, phospho‐tau, and beta‐amyloid and neuropsychological functions in Parkinson's disease

Alzheimers disease (AD)‐pathology may play a role in Parkinsons disease (PD)‐related dementia (PDD). The aim of this study was to assess cerebrospinal fluid (CSF) levels of tau, phospho‐tau, and beta‐amyloid, proposed AD biomarkers, and their relationship with cognitive function in PD. Forty PD patients [20 nondemented (PDND); 20 PDD] and 30 controls underwent CSF tau, phospho‐tau, and beta‐amyloid analysis using specific ELISA techniques. All PD patients and 15 controls underwent neuropsychological testing of fronto‐subcortical (attention, fluency) and neocortical (memory, naming, visuoperceptive) functions. CSF markers levels were compared between groups, and compared and correlated with neuropsychological measures in PDND and PDD separately and as a continuum (PD). CSF tau and phospho‐tau were higher in PDD than in PDND and controls (P < 0.05). CSF beta‐amyloid ranged from high (controls) to intermediate (PDND) and low (PDD) levels (P < 0.001). In all PD and PDD patients, high CSF tau and phospho‐tau were associated with impaired memory and naming. In PDND, CSF beta‐amyloid was related with phonetic fluency. These findings suggest underlying AD‐pathology in PDD in association with cortical cognitive dysfunction, and that low CSF beta‐amyloid in PDND patients with impaired phonetic fluency can constitute an early marker of cognitive dysfunction.

Multiple organ involvement by alpha‐synuclein pathology in Lewy body disorders

Lewy body (LB) diseases are characterized by alpha‐synuclein (AS) aggregates in the central nervous system (CNS). Involvement of the peripheral autonomic nervous system (pANS) is increasingly recognized, although less studied. The aim of this study was to systematically analyze the distribution and severity of AS pathology in the CNS and pANS. Detailed postmortem histopathological study of brain and peripheral tissues from 28 brain bank donors (10 with Parkinsons disease [PD], 5 with dementia with LB [DLB], and 13 with non‐LB diseases including atypical parkinsonism and non‐LB dementia). AS aggregates were found in the pANS of all 15 LB disease cases (PD, DLB) in stellate and sympathetic ganglia (100%), vagus nerve (86.7%), gastrointestinal tract (86.7%), adrenal gland and/or surrounding fat (53.3%), heart (100%), and genitourinary tract (13.3%), as well as in 1 case of incidental Lewy body disease (iLBD). A craniocaudal gradient of AS burden in sympathetic chain and gastrointestinal tract was observed. DLB cases showed higher amounts of CNS AS aggregates than PD cases, but this was not the case in the pANS. No pANS AS aggregates were detected in Alzheimers disease (AD) cases with or without CNS AS aggregates. All pathologically confirmed LB disease cases including 1 case of iLBD had AS aggregates in the pANS with a craniocaudal gradient of pathology burden in sympathetic chain and gastrointestinal tract. AS was not detected in the pANS of any AD case. These findings may help in the search of peripheral AS aggregates in vivo for the early diagnosis of PD.

Clinical overview of the synucleinopathies

The term synucleinopathies is used to name a group of neurodegenerative disorders characterized by fibrillary aggregates of α‐synuclein protein in the cytoplasm of selective populations of neurons and glia. These disorders include Parkinsons disease (PD), dementia with Lewy bodies (DLB), pure autonomic failure (PAF), and multiple system atrophy (MSA). Clinically, they are characterized by a chronic and progressive decline in motor, cognitive, behavioural, and autonomic functions, depending on the distribution of the lesions. Because of clinical overlap, differential diagnosis is sometimes very difficult. Parkinsonism is the predominant symptom of PD, but it can be indistinguishable from the parkinsonism of DLB and MSA. Autonomic dysfunction, which is an isolated finding in PAF, may be present in PD and DLB, but is usually more prominent and appears earlier in MSA. DLB could be the same disease as PD but with widespread cortical pathological states, leading to dementia, fluctuating cognition, and the characteristic visual hallucinations. The deposition of aggregates of synuclein in neurons and glia suggests that a common pathogenic mechanism may exist for these disorders. Even though synuclein may play an important role in disease development in these disorders, in light of the different symptom complex and prognosis and management issues that characterize each disorder, we think that the term synucleinopathy has little practical value as a diagnostic term for the clinician. Clinicians should attempt to reach standard clinical diagnosis on patients, such as PD, PAF, or MSA.

Longitudinal evaluation of cerebral morphological changes in Parkinson's disease with and without dementia

AbstractObjectiveTo investigate the pattern of brain atrophy across time in a sample of Parkinsons disease (PD) patients with and without dementia using voxelbased morphometry (VBM) analysis.MethodsThe initial sample comprised thirteen non–demented PD patients and sixteen demented patients. Longitudinal cognitive assessment and structural MRI were performed. The mean follow–up period was 25 months (SD = 5.2). From this initial group, eight PD patients with dementia (5 men and 3 women) and eleven PD patients without dementia (7 men and 4 women) were reevaluated. MRI 3D structural images were acquired and analyzed by means of the optimized VBM procedure with Statistical Parametric Mapping (SPM2).ResultsVBM analysis showed a progressive grey matter volume decrease in patients with PD without dementia in limbic, paralimbic and neocortical associative temporooccipital regions. In patients with dementia the loss mainly involved neocortical regions.ConclusionVBM revealed a significant loss of grey matter volume in PD patients with and without dementia with disease progression. The decrease in limbic and paralimbic regions is widespread in non–demented patients. Neocortical volume reduction is the most relevant finding in patients with dementia. This suggests that the neocortex is a substrate for dementia in Parkinson disease.

Mitochondria1 respiratory chain activity in skeletal muscle from patients with Parkinson's disease

Different abnormalities in mitochondrial electron transport chain activity have been demonstrated in muscle and other tissues of patients with idiopathic Parkinsons disease (PD). We studied eight Spanish patients with PD to evaluate the functional activity of the electron transport chain in muscle mitochondria from patients of this country. We found lower complex I activity (nmol.min-1.mg−1) in patients (245.8 ± 42.8) than in controls (331.6 ± 60.1) (p = 0.004) and lower complex IV activity in patients (46.1 ± 9) than in controls (144.1 ± 42.3) (p = 0.00001). Complex V activity was also decreased in two patients and complex II and III activities were normal in all of them. Although these results strongly suggest an alteration in mitochondrial DNA in PD, the various electron transport chain defects in different tissues seem to be nonspecific.