Intestinal histomorphological and molecular alterations in patients with Parkinson's disease.

BACKGROUND AND PURPOSE: Changes in gut microbiota composition, enteric inflammation, impairments of the intestinal epithelial barrier and neuroplastic changes in the enteric nervous system have been reported in Parkinson's disease (PD) patients and could contribute to the onset of both neurological and gastrointestinal symptoms. However, their mutual interplay has rarely been investigated. This study evaluated, in an integrated manner, changes in faecal microbiota composition, morphofunctional alterations of colonic mucosal barrier and changes of inflammatory markers in blood and stools of PD patients. METHODS: Nineteen PD patients and nineteen asymptomatic subjects were enrolled. Blood lipopolysaccharide binding protein (LBP, marker of altered intestinal permeability) and interleukin-1ß (IL-1ß) levels, as well as stool IL-1ß and tumour necrosis factor (TNF) levels, were evaluated. Gut microbiota analysis was performed. Epithelial mucins, collagen fibres, claudin-1 and S100-positive glial cells as markers of an impairment of the intestinal barrier, mucosal remodelling and enteric glial activation were evaluated on colonic mucosal specimens collected during colonoscopy. RESULTS: Faecal microbiota analysis revealed a significant difference in the α-diversity in PD patients compared to controls, while no differences were found in the ß-diversity. Compared to controls, PD patients showed significant chenags in plasma LBP levels, as well as faecal TNF and IL-1ß levels. The histological analysis showed a decrease in epithelial neutral mucins and claudin-1 expression and an increased expression of acidic mucins, collagen fibres and S100-positive glial cells. CONCLUSIONS: Parkinson's disease patients are characterized by enteric inflammation and increased intestinal epithelial barrier permeability, as well as colonic mucosal barrier remodelling, associated with changes in gut microbiota composition.

Evaluation of iron overload in nigrosome 1 via quantitative susceptibility mapping as a progression biomarker in prodromal stages of synucleinopathies.

Idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is a prodromal stage of α-synucleinopathies, such as Parkinson's disease (PD), which are characterized by the loss of dopaminergic neurons in substantia nigra, associated with abnormal iron load. The assessment of presymptomatic biomarkers predicting the onset of neurodegenerative disorders is critical for monitoring early signs, screening patients for neuroprotective clinical trials and understanding the causal relationship between iron accumulation processes and disease development. Here, we used Quantitative Susceptibility Mapping (QSM) and 7T MRI to quantify iron deposition in Nigrosome 1 (N1) in early PD (ePD) patients, iRBD patients and healthy controls and investigated group differences and correlation with disease progression. We evaluated the radiological appearance of N1 and analyzed its iron content in 35 ePD, 30 iRBD patients and 14 healthy controls via T2*-weighted sequences and susceptibility (χ) maps. N1 regions of interest (ROIs) were manually drawn on control subjects and warped onto a study-specific template to obtain probabilistic N1 ROIs. For each subject the N1 with the highest mean χ was considered for statistical analysis. The appearance of N1 was rated pathological in 45% of iRBD patients. ePD patients showed increased N1 χ compared to iRBD patients and HC but no correlation with disease duration, indicating that iron load remains stable during the early stages of disease progression. Although no difference was reported in iron content between iRBD and HC, N1 χ in the iRBD group increases as the disease evolves. QSM can reveal temporal changes in N1 iron content and its quantification may represent a valuable presymptomatic biomarker to assess neurodegeneration in the prodromal stages of PD.

Iron-sensitive MR imaging of the primary motor cortex to differentiate hereditary spastic paraplegia from other motor neuron diseases.

OBJECTIVES: Hereditary spastic paraplegia (HSP) is a group of genetic neurodegenerative diseases characterised by upper motor neuron (UMN) impairment of the lower limbs. The differential diagnosis with primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) can be challenging. As microglial iron accumulation was reported in the primary motor cortex (PMC) of ALS cases, here we assessed the radiological appearance of the PMC in a cohort of HSP patients using iron-sensitive MR imaging and compared the PMC findings among HSP, PLS, and ALS patients. METHODS: We included 3-T MRI scans of 23 HSP patients, 7 PLS patients with lower limb onset, 8 ALS patients with lower limb and prevalent UMN onset (UMN-ALS), and 84 ALS patients with any other clinical picture. The PMC was visually rated on 3D T2*-weighted images as having normal signal intensity, mild hypointensity, or marked hypointensity, and differences in the frequency distribution of signal intensity among the diseases were investigated. RESULTS: The marked hypointensity in the PMC was visible in 3/22 HSP patients (14%), 7/7 PLS patients (100%), 6/8 UMN-ALS patients (75%), and 35/84 ALS patients (42%). The frequency distribution of normal signal intensity, mild hypointensity, and marked hypointensity in HSP patients was different than that in PLS, UMN-ALS, and ALS patients (p < 0.01 in all cases). CONCLUSIONS: Iron-sensitive imaging of the PMC could provide useful information in the diagnostic work - up of adult patients with a lower limb onset UMN syndrome, as the cortical hypointensity often seen in PLS and ALS cases is apparently rare in HSP patients. KEY POINTS: • The T2* signal intensity of the primary motor cortex was investigated in patients with HSP, PLS with lower limb onset, and ALS with lower limb and prevalent UMN onset (UMN-ALS) using a clinical 3-T MRI sequence. • Most HSP patients had normal signal intensity in the primary motor cortex (86%); on the contrary, all the PLS and the majority of UMN-ALS patients (75%) had marked cortical hypointensity. • The T2*-weighted imaging of the primary motor cortex could provide useful information in the differential diagnosis of sporadic adult-onset UMN syndromes.

Morphometric imaging and quantitative susceptibility mapping as complementary tools in the diagnosis of parkinsonisms.

BACKGROUND AND PURPOSE: In the quest for in vivo diagnostic biomarkers to discriminate Parkinson's disease (PD) from progressive supranuclear palsy (PSP) and multiple system atrophy (MSA, mainly p phenotype), many advanced magnetic resonance imaging (MRI) techniques have been studied. Morphometric indices, such as the Magnetic Resonance Parkinsonism Index (MRPI), demonstrated high diagnostic value in the comparison between PD and PSP. The potential of quantitative susceptibility mapping (QSM) was hypothesized, as increased magnetic susceptibility (Δχ) was reported in the red nucleus (RN) and medial part of the substantia nigra (SNImed) of PSP patients and in the putamen of MSA patients. However, disease-specific susceptibility values for relevant regions of interest are yet to be identified. The aims of the study were to evaluate the diagnostic potential of a multimodal MRI protocol combining morphometric and QSM imaging in patients with determined parkinsonisms and to explore its value in a population of undetermined cases. METHOD: Patients with suspected degenerative parkinsonism underwent clinical evaluation, 3 T brain MRI and clinical follow-up. The MRPI was manually calculated on T1-weighted images. QSM maps were generated from 3D multi-echo T2*-weighted sequences. RESULTS: In determined cases the morphometric evaluation confirmed optimal diagnostic accuracy in the comparison between PD and PSP but failed to discriminate PD from MSA-p. Significant nigral and extranigral differences were found with QSM. RN Δχ showed excellent diagnostic accuracy in the comparison between PD and PSP and good accuracy in the comparison of PD and MSA-p. Optimal susceptibility cut-off values of RN and SNImed were tested in undetermined cases in addition to MRPI. CONCLUSIONS: A combined use of morphometric imaging and QSM could improve the diagnostic phase of degenerative parkinsonisms.

Bipolar Spectrum disorders in Parkinson's disease: a systematic evaluation.

OBJECTIVE: Psychiatric disorders are very common in patients affected by Parkinson's disease (PD). However, comorbidity with Bipolar Spectrum disorders is understudied. The aim of this study is to explore the clinical correlates of PD associated with Bipolar Spectrum disorders. METHODS: One hundred PD patients were screened for psychiatric comorbidities, cognitive profile, motor, and non-motor symptoms. The sample was divided into three groups: PD-patients with Bipolar Spectrum disorders (bipolar disorder type I, type II, and spontaneous or induced hypomania; N = 32), PD-patients with others psychiatric comorbidities (N = 39), PD-patients without psychiatric comorbidities (N = 29). Clinical features were compared among the groups using analysis of variance and chi-square test. A logistic regression was performed to evaluate the association between Bipolar Spectrum disorders and early onset of PD (≤50 years) controlling for lifetime antipsychotic use. RESULTS: In comparison with PD patients with and without other psychiatric comorbidity, subjects affected by Bipolar Spectrum disorders were younger, showed more frequently an early onset PD, reported more involuntary movements and a higher rate of impulse control disorders and compulsive behaviors. No differences were observed in indexes of exposure to dopamine agonist treatments. The early onset of PD was predicted by Bipolar Spectrum comorbidity, independently from lifetime antipsychotic use. CONCLUSION: Bipolar Spectrum disorders are common in early onset PD. The presence of bipolar comorbidity could identify a particular subtype of PD, showing higher rates of neurological and psychiatric complications and deserving further investigation.

Positive DAT-SCAN in SPG7: a case report mimicking possible MSA-C.

BACKGROUND: Spastic Paraplegia type 7 (SPG7) is one of the most common autosomal recessive Hereditary Spastic Paraplegias (HSP); Spastic Paraplegias (SPGs) can present as hereditary ataxias. However, ataxia is frequently the symptom of presentation of many other hereditary/sporadic disorders, such as Multiple system atrophy type C (MSA-C), an α-synuclein sporadic neurodegenerative disorder, in which cerebellar ataxia is one of the main clinical features. Dopamine Transporter imaging (DAT-SCAN), associated with clinical features, can be a helpful tool in order to distinguish MSA-C from other causes of ataxia. CASE-PRESENTATION: We present the case of a 70-year-old man with gait difficulties over a period of 3 years and frequent backward/lateral falls. He also reported urinary urge incontinence, but no symptoms that are compatible with orthostatic hypotension. On neurological examination he showed ataxic gait, spasticity in the left lower limb and trunk and limb ataxia, especially on the left side. Mild hypokinesia was found in all 4 limbs, especially in the left foot. MRI revealed atrophy of the cerebellar hemispheres and vermis. DAT-SCAN imaging revealed bilateral nigro-striatal degeneration, which was compatible with a diagnosis of possible MSA-C. Considering the atypical disease course (the patient walked without any support after 3 years), we carried out a genetic investigation for Ataxia, and a mutation in SPG7 was found. CONCLUSIONS: DAT-SCAN imaging, evaluated together with the clinical findings, can be useful for differentiating MSA from other possible causes of adult-onset Ataxia. Indeed, patients with MSA-C generally show a decreased uptake of dopamine transporters in DAT-SCAN imaging. Ours is the first case reported in the literature of a patient with SPG7 mutation with nigrostriatal degeneration and a clinical presentation of a possible MSA-C. Performing genetic investigations in patients with an atypical disease course is important to avoid MSA-mimicries. Identifying the correct diagnosis is important not only for prognostic reasons, but also for possible future genetic therapies.

Reduced oligodendrocyte exosome secretion in multiple system atrophy involves SNARE dysfunction.

Transportation of key proteins via extracellular vesicles has been recently implicated in various neurodegenerative disorders, including Parkinson's disease, as a new mechanism of disease spreading and a new source of biomarkers. Extracellular vesicles likely to be derived from the brain can be isolated from peripheral blood and have been reported to contain higher levels of α-synuclein (α-syn) in Parkinson's disease patients. However, very little is known about extracellular vesicles in multiple system atrophy, a disease that, like Parkinson's disease, involves pathological α-syn aggregation, though the process is centred around oligodendrocytes in multiple system atrophy. In this study, a novel immunocapture technology was developed to isolate blood CNPase-positive, oligodendrocyte-derived enriched microvesicles (OEMVs), followed by fluorescent nanoparticle tracking analysis and assessment of α-syn levels contained within the OEMVs. The results demonstrated that the concentrations of OEMVs were significantly lower in multiple system atrophy patients, compared to Parkinson's disease patients and healthy control subjects. It is also noted that the population of OEMVs involved was mainly in the size range closer to that of exosomes, and that the average α-syn concentrations (per vesicle) contained in these OEMVs were not significantly different among the three groups. The phenomenon of reduced OEMVs was again observed in a transgenic mouse model of multiple system atrophy and in primary oligodendrocyte cultures, and the mechanism involved was likely related, at least in part, to an α-syn-mediated interference in the interaction between syntaxin 4 and VAMP2, leading to the dysfunction of the SNARE complex. These results suggest that reduced OEMVs could be an important mechanism related to pathological α-syn aggregation in oligodendrocytes, and the OEMVs found in peripheral blood could be further explored for their potential as multiple system atrophy biomarkers.

Connected speech in progressive supranuclear palsy: a possible role in differential diagnosis.

BACKGROUND: Progressive supranuclear palsy (PSP) is an atypical Parkinsonism characterized by motor and neuropsycological disorders. Language could be impaired in PSP patients, also in Richardson variant (PSP-RS). The analysis of connected speech is used in neurodegenerative disorder to investigate different levels of language organization, including phonetic, phonological, lexico-semantic, morpho-syntactic, and pragmatic processing. OBJECTIVE: In our study, we aimed to investigate the language profile, especially connected speech, in early-stage PSP-RS and Parkinson's disease (PD) patients without predominant speech or language disorders. METHODS: Language was assessed using the Screening for Aphasia in NeuroDegeneration (SAND); connected speech analysis was conducted from the picture description subtest. RESULTS: We enrolled 48 patients, 22 PD and 26 PSP (18 PSP-RS and 8 non-RS). PSP-RS patients presented an impairment in language domain, particularly regarding connected speech. PSP-RS patients presented worse performances than PD in different scores. The output of PSP-RS patients was characterized by a reduction in number of sentences and subordinates with respect to PD; PSP presented also more repaired sequences and phonological and lexico-semantic errors than PD. Number of sentences and number of subordinates of the picture description task were identified as predictors of PSP diagnosis. CONCLUSION: In summary, the SAND scale is able to identify language impairment in PSP patients. The analysis of connected speech could highlight some important aspects of language impairment in PSP-RS patients, and it could be helpful in the differential diagnosis with PD.

Is DAT imaging abnormality in normal pressure hydrocephalus always suggestive of degeneration?

Idiopathic normal pressure hydrocephalus (iNPH) is a debated entity with controversial pathogenesis, diagnostic criteria, and predictors of response after ventriculoperitoneal shunt (VPS). Parkinsonian signs are frequently reported in the clinical picture, sometimes due to the coexistence of an underlying neurodegenerative parkinsonism and sometimes in the absence thereof. To distinguish these two scenarios is crucial, since they may carry different long-term response to CSF drainage. 123I-FP-CIT-SPECT was believed to be helpful in this regard, however its role in predicting surgical outcome has been disputed. We illustrate a patient presented with gait disturbance, urinary incontinence, and asymmetrical parkinsonian signs, who underwent a 3T brain MRI and a 123I-FP-CIT-SPECT. VPS was performed. The patient repeated a 123I-FP-CIT-SPECT, 18 months after the operation, and was clinically followed up for 24 months. Our patient displayed clinical and radiological criteria for iNPH and an abnormal asymmetrical uptake in 123I-FP-CIT-SPECT, consistent with her asymmetrical parkinsonism. However, the organization of the substantia nigra studied with iron-sensitive sequences in 3T brain MRI scan appeared intact. The patient revealed an improvement both clinically and in 123I-FP-CIT-SPECT at postsurgical follow-up. Our report suggests that abnormal 123I-FP-CIT-SPECT may not necessarily reveal an overlap with neurodegenerative parkinsonism; its partial reversibility may suggest that the mechanical effect exerted on the striatum by ventriculomegaly ultimately leads to downregulation of dopaminergic transporters which may improve after VPS.

Midbrain MRI assessments in progressive supranuclear palsy subtypes.

OBJECTIVES: To explore the role of the available midbrain-based MRI morphometric assessments in (1) differentiating among progressive supranuclear palsy (PSP) subtypes (PSP Richardson's syndrome (PSP-RS), PSP with predominant parkinsonism (PSP-P) and the other variant syndromes of PSP (vPSP)), and (2) supporting the diagnosis of PSP subtypes compared with Parkinson's disease (PD) and healthy controls (HC). METHODS: Seventy-eight patients with PSP (38 PSP-RS, 21 PSP-P and 19 vPSP), 35 PD and 38 HC were included in the present analysis. Available midbrain-based MRI morphometric assessments were calculated for all participants. RESULTS: Current MRI midbrain-based assessments do not display an adequate sensitivity and specificity profile in differentiating PSP subtypes. On the other hand, we confirmed MR Parkinsonism Index (MRPI) and pons area to midbrain area ratio (P/M) have adequate diagnostic value to support PSP-RS clinical diagnosis compared with both PD and HC, but low sensitivity and specificity profile in differentiating PSP-P from PD as well as from HC. The same measures show acceptable sensitivity and specificity profile in supporting clinical diagnosis of vPSP versus HC but not versus PD. Similar findings were detected for the newer MRPI and P/M versions. CONCLUSIONS: Further studies are warranted to identify neuroimaging biomarkers supporting the clinical phenotypic categorisation of patients with PSP. MRPI and P/M have diagnostic value in supporting the clinical diagnosis of PSP-RS. CLASSIFICATION OF EVIDENCE: This study provides class III evidence that available MRI midbrain-based assessments do not have diagnostic value in differentiating the Movement Disorder Society PSP subtypes.

Dopamine Transporter, Age, and Motor Complications in Parkinson's Disease: A Clinical and Single-Photon Emission Computed Tomography Study.

BACKGROUND: Previous molecular imaging studies comparing dopamine function in vivo between early-onset PD and late-onset PD patients have shown contradictory results, presumably attributable to the aging-related decline in nigrostriatal function. OBJECTIVES: (1) To investigate baseline dopamine transporter availability in early-onset PD (<55 years) and late-onset PD (>70 years) patients, z-scores values of putamen and caudate [123 I]-ioflupane uptake were calculated using the respective age-matched controls in order to correct for early presynaptic compensatory mechanisms and age-related dopamine neuron loss; (2) to examine the associations of such baseline single-photon emission computed tomography measures with the emergence of late-disease motor complications. METHODS: In this retrospective study, 105 de novo PD patients who underwent [123 I]-ioflupane single-photon emission computed tomography at time of diagnosis were divided into three tertile groups according to age at disease onset (35 early-onset PD and 40 late-onset PD patients). Z-scores were compared between the two groups, and their predictive power for motor complications (during a mean follow-up of 7 years) was evaluated using Cox proportional hazard models. RESULTS: Despite a less-severe motor phenotype, early-onset PD patients exhibited more reduced [123 I]-ioflupane binding in the putamen and had a higher and earlier risk for developing motor complications than those with late-onset PD. Lower [123 I]-Ioflupane uptake in the putamen and caudate increased the risk of motor complications. CONCLUSIONS: Our findings indicate that a lower dopamine transporter binding in early-onset PD predicts the later development of motor complications, but it is not related to severity of motor symptoms, suggesting age-related differences in striatal compensatory mechanisms in PD. © 2020 International Parkinson and Movement Disorder Society.

Theory of mind in Parkinson's disease: evidences in drug-naïve patients and longitudinal effects of dopaminergic therapy.

Theory of mind (ToM) is the ability to attribute mental states to one self and others and to understand that others have beliefs different from one's own. Different subcomponents of ToM have also been identified: cognitive and affective. Cognitive ToM refers to the capacity to infer others' beliefs and intentions, while affective ToM implies the ability to appreciate others' emotional states. The aim of this study was to explore ToM in drug-naïve Parkinson's disease (PD) patients and to investigate the effects of chronic dopaminergic therapy on different subcomponents of ToM during a 3 months and 1 year of follow-up. We examined 16 PD patients in three conditions: before (un-medicated) and after dopaminergic therapy (medicated 3 months: T1 and medicated 1 year: T2). We also compared our PD's ToM abilities with 11 healthy individuals. ToM was explored with 5 different tasks: Faux Pas Test, Picture Sequencing Task Capture Story, Emotion Attribution Task, Strange Stories Task, and Karolinska Directed Emotional Faces. Our study confirms that PD patients present deficits in cognitive components of ToM and preserved performances in the affective ones in early stages of disease. We also find a significant effect of dopaminergic therapy on ToM already after 3 months with a good persistency after 1 year of treatment.

Validation of the Italian version of the PSP Quality of Life questionnaire.

BACKGROUND: Progressive supranuclear palsy (PSP) is a rare rapidly progressive, neurodegenerative disease characterized by falls and ocular movement disturbances. The use of health-related quality of life (HR-QoL) measures allows assessing changes in health status induced by therapeutic interventions or disease progress in neurodegenerative diseases. The PSP-QoL is a 45-item, self-administered questionnaire designed to evaluate HR-QoL in PSP. METHODS AND RESULTS: Here, the PSP-QoL was translated into Italian and validated in 190 PSP (96 women and 94 men; mean age ± standard deviation, 72 ± 6.5; mean disease duration, 4.2 ± 2.3) patients diagnosed according to the Movement Disorder Society criteria and recruited in 16 third level movement disorders centers participating in the Neurecanet project. The mean PSP-QoL total score was 77.8 ± 37 (physical subscore, 46.5 ± 18.7; mental subscore, 33.6 ± 19.2). The internal consistency was high (Cronbach's alpha = 0.954); corrected item-total correlation was > 0.40 for the majority of items. The significant and moderate correlation of the PSP-QoL with other HR-QoL measures as well as with motor and disability assessments indicated adequate convergent validity of the scale. Gender and geographic location presented a significant impact on the PSP-QoL in our sample with women and patients from the South of Italy scoring higher than their counterparts. CONCLUSION: In conclusion, the Italian version of the PSP-QoL is an easy, reliable and valid tool for assessment of HR-QoL in PSP.

Validation of the Italian version of carers' quality-of-life questionnaire for parkinsonism (PQoL Carer) in progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is a rare, rapidly progressive, neurodegenerative disease characterized by falls and ocular movement disturbances. Caring for a partner or relative who suffers from PSP entails a strenuous and demanding task, usually lasting for years that affects carers' everyday life routines and emotional and social well-being. The 26-item Parkinsonism Carers QoL (PQoL Carer) is a self-administered, concise instrument evaluating the quality of life of caregivers of patients with atypical parkinsonism (both PSP and multiple system atrophy). Here, the PQoL Carer was translated into Italian and validated in 162 carers of PSP patients (54.3% women; mean age (standard deviation), 62.4 (15.4)) diagnosed according to the Movement Disorder Society criteria and recruited in 16 third-level movement disorders centers participating in the Neurecanet project. The mean PQoL total score was 40.66 ± 19.46. The internal consistency was excellent (Cronbach's alpha = 0.941); corrected item-total correlation was > 0.40 for all the items. A correlation with other health-related quality of life measures as well as with behavioral assessments was shown suggesting adequate convergent validity of the scale. PQoL also correlated with patients' severity of disease. The discriminant validity of the scale was evidenced by its capacity to differentiate between carers with varying levels of self-reported health (p < 0.001). In conclusion, the Italian version of the PQoL Carer is an easy, consistent, and valid tool for the assessment of the quality of life in carers of PSP patients.

Present and Future of Ultra-High Field MRI in Neurodegenerative Disorders.

PURPOSE OF REVIEW: With a high signal-to-noise ratio, unparalleled spatial resolution, and improved contrasts, ultra-high field MR (≥ 7 T) has great potential in depicting the normal radiological anatomy of smaller structures in the brain and can also provide more information about morphological, quantitative, and metabolic changes associated with a wide range of brain disorders. By focusing attention on specific brain regions believed to be associated with early pathological change, or by more closely inspecting recognized foci of brain pathology, ultra-high field MR can improve the accuracy and sensitivity of neuroimaging. This article reviews recent studies at ultra-high field about Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). RECENT FINDINGS: The research on AD has mainly focused on detecting the thinning of hippocampal layers and the susceptibility effect supposed to be related to beta-amyloid deposition. In patients with PD, atypical parkinsonisms and subjects at risk of developing motor symptoms of Parkinson's disease, the main aim was to detect changes in the substantia nigra, probably related to increased iron deposition. In patients with ALS, both brain and spinal cord were investigated, with the aim of finding changes in the primary motor cortex and corticospinal tract which reflect neurodegeneration and neuroinflammation. Ultra-high field MR was shown to be useful for detecting subtle brain changes in patients with AD, and possible new diagnostic biomarkers in patients with PD and ALS were discovered. The ability of 7 T MR to provide prognostic biomarkers in subjects at risk for developing synucleinopathies is currently under evaluation.

Neuroimaging in Parkinson's disease: focus on substantia nigra and nigro-striatal projection.

PURPOSE OF REVIEW: The diagnosis of Parkinson disease is based on clinical features; however, unmet need is an imaging signature for Parkinson disease and the early differential diagnosis with atypical parkinsonisms. A summary of the molecular imaging and MRI recent evidences for Parkinson disease diagnosis will be presented in this review. RECENT FINDINGS: The nigro-striatal dysfunction explored by dopamine transporter imaging is not a mandatory diagnostic criterion for Parkinson disease, recent evidence supported its utility as in-vivo proof of degenerative parkinsonisms, and there might be compensatory mechanisms leading to an early overestimation. The visualization of abnormalities in substantia nigra by MRI has been recently described as sensitive and specific tool for Parkinson disease diagnosis, even in preclinical conditions, whereas it is not useful for distinguishing between Parkinson disease and atypical parkinsonisms. The relationship between the nigral anatomical changes, evaluated as structural alterations or neuromelanin signal decrease and the dopaminergic nigro-striatal function needs to be further clarified. SUMMARY: With the hopeful advent of potential neuroprotective drugs for PD, it is crucial to have imaging measures that are able to detect at risk subjects. Moreover it is desirable to increase the knowledge about which measure better predicts the probability and the time of clinical conversion to PD.

Nigral involvement in atypical parkinsonisms: evidence from a pilot study with ultra-high field MRI.

Ten healthy subjects (HS) and 15 patients with atypical parkinsonisms underwent 7-T susceptibility-weighted-imaging MR to evaluate substantia nigra (SN). All HS were judged "normal". Twelve out of 15 patients exhibited bilateral abnormal SN while three patients with corticobasal degeneration (CBD) showed bilateral normal aspect of SN. Anatomical changes of SN at 7 T occur in multiple system atrophy and progressive supranuclear palsy as previously reported in Parkinson's disease. Preserved SN in CBD confirms the pathological heterogeneity of this disease.

MR imaging of the substantia nigra at 7 T enables diagnosis of Parkinson disease.

PURPOSE: To evaluate the anatomy of the substantia nigra (SN) in healthy subjects by performing 7-T magnetic resonance (MR) imaging of the SN, and to prospectively define the accuracy of 7-T MR imaging in distinguishing Parkinson disease (PD) patients from healthy subjects on an individual basis. MATERIALS AND METHODS: The 7-T MR imaging protocol was approved by the Italian Ministry of Health and by the local competent ethics committee. SN anatomy was described ex vivo on a gross brain specimen by using highly resolved proton-density (spin-echo proton density) and gradient-recalled-echo (GRE) images, and in vivo in eight healthy subjects (mean age, 40.1 years) by using GRE three-dimensional multiecho susceptibility-weighted images. After training on appearance of SN in eight healthy subjects, the SN anatomy was evaluated twice by two blinded observers in 13 healthy subjects (mean age, 54.7 years) and in 17 PD patients (mean age, 56.9 years). Deviations from normal SN appearance were described and indicated as abnormal, and both diagnostic accuracy and intra- and interobserver agreement for diagnosis of PD with 7-T MR imaging were calculated. RESULTS: Three-dimensional multiecho susceptibility-weighted 7-T MR imaging reveals a three-layered organization of the SN allowing readers to distinguish pars compacta ventralis and dorsalis from pars reticulata. The abnormal architecture of the SN allowed a discrimination between PD patients and healthy subjects with sensitivity and specificity of 100% and 96.2% (range, 92.3%-100%), respectively. Intraobserver agreement (κ = 1) and interobserver agreement (κ = 0.932) were excellent. CONCLUSION: MR imaging at 7-T allows a precise characterization of the SN and visualization of its inner organization. Three-dimensional multiecho susceptibility-weighted images can be used to accurately differentiate healthy subjects from PD patients, which provides a novel diagnostic opportunity.

A pilot psychometric study of aberrant salience state in patients with Parkinson's disease and its association with dopamine replacement therapy.

An overactive striatal dopaminergic neurotransmission is described in psychosis and may be associated with a state of aberrant salience attribution. This pilot psychometric study investigated if features suggestive of an aberrant salience state, a condition of psychosis proneness, are associated with dopamine replacement therapy in patients with early Parkinson's disease (PD). 77 participants (50 medicated PD patients, 12 newly diagnosed drug-naive PD patients and 15 healthy controls) were enrolled and assessed with the Aberrant Salience Inventory (ASI). Differences between groups were found for ASI scores, and ASI scores correlated with the dopaminergic therapy, in particular levodopa. These findings preliminary suggested that the presence and the degree of an aberrant salience state may be associated with features of the dopaminergic therapy; further studies are needed to investigate which neuropsychiatric complications more common in PD patients may be characterized by an underlying aberrant salience state.