Daniela Frosini

Mild cognitive impairment and cognitive-motor relationships in newly diagnosed drug-naive patients with Parkinson's disease

Background and aims (1) To establish the prevalence of mild cognitive impairment (MCI) in newly diagnosed drug-naive patients with Parkinsons disease adopting recently proposed and more conservative preliminary research criteria. (2) To investigate the relation between cognitive performances, MCI and motor dysfunction. Methods 132 consecutive newly diagnosed drug-naive PD patients and 100 healthy controls (HCs) underwent a neuropsychological evaluation covering different cognitive domains. Moreover, on the basis of the Unified Parkinsons Disease Rating Scale II/III, different motor scores were calculated and patients were classified in motor subtypes. 11 patients were excluded from the analysis during clinical follow-up which was continued at least 3 years from the diagnosis; therefore, the final sample included 121 patients. Results MCI prevalence was higher in PD (14.8%) patients than in HCs (7.0%). PD patients reported lower cognitive performances than HCs in several cognitive domains; HCs also outperformed cognitively preserved PD patients in tasks of episodic verbal memory and in a screening task of executive functions. MCI-PD patients presented a more severe bradykinesia score than non-MCI PD patients and patients mainly characterised by tremor had better performances in some cognitive domains, and specific cognitive-motor relationships emerged. Conclusions Although the adoption of more conservative diagnostic criteria identified a lower MCI prevalence, we found evidence that newly diagnosed drug-naive PD patients present a higher risk of MCI in comparison with HCs. Axial symptoms and bradykinesia represent risk factors for MCI in PD patients and a classification of PD patients that highlights the presence/absence of tremor, as proposed in this study, is probably better tailored for the early stages of PD than classifications proposed for more advanced PD stages.

Impulse control disorders in Parkinson's disease: definition, epidemiology, risk factors, neurobiology and management

There is increasing awareness that impulse control disorders (ICDs), including pathological gambling, hyper-sexuality, compulsive eating and buying, can occur as a complication of Parkinsons disease (PD). In addition, other impulsive or compulsive disorders have been reported to occur, including dopamine dysregulation syndrome (DDS) and punding. Case reports and prospective studies have reported an association between ICDs and the use of dopamine receptor agonists at higher doses, and DDS has been associated with L-dopa at higher doses or short-acting dopamine receptor agonists. Risk factors for ICDs include male sex, younger age or younger age at PD onset, a pre-PD history of ICD symptoms, history of substance use or bipolar disorder, and a personality profile characterized by impulsiveness. The management of clinically significant ICD symptoms should consist of modifications to dopamine replacement therapy, particularly dopamine receptor agonists, which is usually associated with an improvement of ICDs. There is no empirical evidence supporting the use of psychiatric drugs for ICDs in PD. Functional neuroimaging studies such as functional MRI and PET can investigate in vivo the neurobiological basis of these pathological behaviours.

A molecular signature in blood identifies early Parkinson’s disease

BackgroundThe search for biomarkers in Parkinson’s disease (PD) is crucial to identify the disease early and monitor the effectiveness of neuroprotective therapies. We aim to assess whether a gene signature could be detected in blood from early/mild PD patients that could support the diagnosis of early PD, focusing on genes found particularly altered in the substantia nigra of sporadic PD.ResultsThe transcriptional expression of seven selected genes was examined in blood samples from 62 early stage PD patients and 64 healthy age-matched controls. Stepwise multivariate logistic regression analysis identified five genes as optimal predictors of PD: p19 S-phase kinase-associated protein 1A (odds ratio [OR] 0.73; 95% confidence interval [CI] 0.60–0.90), huntingtin interacting protein-2 (OR 1.32; CI 1.08–1.61), aldehyde dehydrogenase family 1 subfamily A1 (OR 0.86; 95% CI 0.75–0.99), 19 S proteasomal protein PSMC4 (OR 0.73; 95% CI 0.60–0.89) and heat shock 70-kDa protein 8 (OR 1.39; 95% CI 1.14–1.70). At a 0.5 cut-off the gene panel yielded a sensitivity and specificity in detecting PD of 90.3 and 89.1 respectively and the area under the receiving operating curve (ROC AUC) was 0.96.The performance of the five-gene classifier on the de novo PD individuals alone composing the early PD cohort (n = 38), resulted in a similar ROC with an AUC of 0.95, indicating the stability of the model and also, that patient medication had no significant effect on the predictive probability (PP) of the classifier for PD risk. The predictive ability of the model was validated in an independent cohort of 30 patients at advanced stage of PD, classifying correctly all cases as PD (100% sensitivity). Notably, the nominal average value of the PP for PD (0.95 (SD = 0.09)) in this cohort was higher than that of the early PD group (0.83 (SD = 0.22)), suggesting a potential for the model to assess disease severity. Lastly, the gene panel fully discriminated between PD and Alzheimer’s disease (n = 29).ConclusionsThe findings provide evidence on the ability of a five-gene panel to diagnose early/mild PD, with a possible diagnostic value for detection of asymptomatic PD before overt expression of the disorder.

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.

Neuropathy and levodopa in Parkinson's disease: Evidence from a multicenter study

The objectives of this study were to evaluate the risk of neuropathy in patients with Parkinsons disease (PD) and to evaluate the role of levodopa exposure as a potential risk factor. A multicenter study of 330 patients with PD and 137 healthy controls with a comparable age distribution was performed. With respect to levodopa exposure, 144 patients had long exposure (≥3 years) to levodopa (LELD), 103 patients had short exposure (<3 years) to levodopa (SELD), and 83 patients had no exposure to levodopa (NOLD). Nerve function was evaluated using the reduced total neuropathy score. Right sural sensory antidromic and peroneal motor nerve conduction studies were performed by neurophysiologists who were blinded to the existence of neuropathy clinical features or PD treatment. Overall, 19.40% of patients in the LELD group, 6.80% in the SELD group, 4.82% in the NOLD group, and 8.76% in the control group were diagnosed with neuropathy (axonal, predominantly sensory). Multivariate logistic analysis indicated that the risk of neuropathy was not influenced by disease duration, severity, or sex. The risk of neuropathy increased by approximately 8% for each year of age (P < 0.001; odds ratio [OR], 1.08; 95% confidence interval [CI], 1.037‐1.128). The risk of neuropathy was 2.38 higher in the LELD group than in the control group (P = 0.022; OR, 2.38; 95% CI, 1.130‐5.014). In a comparison between patients with and without neuropathy (Students t test), the levodopa dose was higher (P < 0.0001), serum vitamin B12 levels were lower (P = 0.0102), and homocysteine levels were higher (P < 0.001) in the patients with neuropathy. Our results demonstrate that the duration of exposure to levodopa, along with age, is the main risk factor for the development of neuropathy. Screening for homocysteine and vitamin B12 levels and clinical‐neurophysiological monitoring for neuropathy may be advisable in patients with PD who are receiving treatment with levodopa.

Decision making in de novo Parkinson's disease

The aim is to study decision making in patients with de novo Parkinsons disease (PD). Recent studies reported that medicated patients with PD have poor performances compared with age‐matched healthy controls in decision making tasks, specially in the Iowa Gambling Task. Two principal causal hypotheses have been proposed to explain this phenomenon: the overdosing effects of dopaminergic therapy on the orbital frontostriatal circuit that is involved in reward processing, or an amygdala dysfunction, as suggested by similar Skin Conductance Responses of patients with PD and amygdala‐damaged patients while performing this task. The assessment of decision making with the Iowa Gambling Task was conducted in 30 nondemented and nondepressed patients with de novo PD and in 25 age‐matched healthy controls. No statistically significant difference emerged between performances of de novo PD patients and performances of healthy controls. De novo PD patients have performances in the Iowa Gambling Task similar to those of age‐matched healthy controls, suggesting that difficulties in decision making emerge, at least in de novo PD patients, by dopaminergic overstimulation of the orbital frontostriatal circuits.

Differences in nigro‐striatal impairment in clinical variants of early Parkinson’s disease: evidence from a FP‐CIT SPECT study

Introduction:  In idiopathic Parkinson’s disease (PD), two different clinical phenotypes are usually distinguished: a tremor dominant variant (TD) and an akinetic‐rigid type (ART). TD patients are characterized by a slower disease progression and a minor cognitive impairment. Striatal density of DAT, as quantified by FP‐CIT SPECT, has been reported to correlate with rigidity and akinesia but not with tremor.

Dopamine Transporter SPECT Imaging in Corticobasal Syndrome

Objective To investigate dopaminergic function in a large cohort of patients with corticobasal syndrome (CBS) and describe its relationship with clinical features in comparison to Parkinsons disease and healthy control subjects. In addition, we assessed prevalence and features of individuals with CBS and in vivo evidence of preserved nigral neuronal density. Background Substantia nigra pars compacta (SNc) neuronal degeneration is a mandatory pathological criterion for definite corticobasal degeneration, though sporadic autopsy-proven cases with ante-mortem imaging evidence of preserved nigral terminals have been recently described. Methods In this multicenter study, we investigated presynaptic nigrostriatal function in 36 outpatients fulfilling clinical criteria for “probable corticobasal degeneration” (age 71±7.3 years; disease duration 3.9±1.6 years), 37 PD and 24 healthy control subjects using FP-CIT single photon emission computed tomography. Clinical, neuropsychological, and magnetic resonance imaging assessment was performed to characterize CBS patients. Linear discriminant analysis was used to categorize normal vs. pathological scans. Results FP-CIT binding reduction in patients with CBS was characterized by larger variability, more uniform reduction throughout the striatum and greater hemispheric asymmetry compared to PD. Moreover, there was no significant correlation between tracer uptake values and clinical features such as disease duration and severity. Despite all CBS subjects showed obvious bilateral extrapyramidal signs, FP-CIT uptake was found to be normal bilaterally in four CBS patients and only unilaterally in other four cases. Extensive clinical, neuropsychological and imaging assessment did not reveal remarkable differences between CBS subjects with normal vs. pathological FP-CIT uptake. Conclusions Our findings support the hypothesis that extrapyramidal motor symptoms in CBS are not invariably associated with SNc neuronal degeneration and that supranigral factors may play a major role in several cases. CBS individuals with normal FP-CIT uptake do not show any clinical or cognitive feature suggesting a different pathology than CBD.

Parkinson's Disease and pathological gambling: Results from a functional MRI study†

Seven patients with a diagnosis of Parkinsons disease (PD) and pathological gambling (PG) and 7 PD patients without PG were investigated by functional MRI and a block‐design experiment with gambling‐related visual cues alternating with neutral stimuli and rest periods. Compared with PD/non‐PG, in PD/PG patients, several areas of increased cue‐related blood oxygen level dependent (BOLD)‐response were observed including bilateral anterior cingulate cortex, medial and superior frontal gyri, and precuneus, right inferior parietal lobule, and ventral striatum. The over activation of cingulate cortex and ventral striatum in PD/PG patients after the craving task is similar to that reported in addicted patients, whereas the activation of the parietal structures is probably related to the attentional network.

Comparison of 3T and 7T Susceptibility-Weighted Angiography of the Substantia Nigra in Diagnosing Parkinson Disease

BACKGROUND AND PURPOSE: Standard neuroimaging fails in defining the anatomy of the substantia nigra and has a marginal role in the diagnosis of Parkinson disease. Recently 7T MR target imaging of the substantia nigra has been useful in diagnosing Parkinson disease. We performed a comparative study to evaluate whether susceptibility-weighted angiography can diagnose Parkinson disease with a 3T scanner. MATERIALS AND METHODS: Fourteen patients with Parkinson disease and 13 healthy subjects underwent MR imaging examination at 3T and 7T by using susceptibility-weighted angiography. Two expert blinded observers and 1 neuroradiology fellow evaluated the 3T and 7T images of the sample to identify substantia nigra abnormalities indicative of Parkinson disease. Diagnostic accuracy and intra- and interobserver agreement were calculated separately for 3T and 7T acquisitions. RESULTS: Susceptibility-weighted angiography 7T MR imaging can diagnose Parkinson disease with a mean sensitivity of 93%, specificity of 100%, and diagnostic accuracy of 96%. 3T MR imaging diagnosed Parkinson disease with a mean sensitivity of 79%, specificity of 94%, and diagnostic accuracy of 86%. Intraobserver and interobserver agreement was excellent at 7T. At 3T, intraobserver agreement was excellent for experts, and interobserver agreement ranged between good and excellent. The less expert reader obtained a diagnostic accuracy of 89% at 3T. CONCLUSIONS: Susceptibility-weighted angiography images obtained at 3T and 7T differentiate controls from patients with Parkinson disease with a higher diagnostic accuracy at 7T. The capability of 3T in diagnosing Parkinson disease might encourage its use in clinical practice. The use of the more accurate 7T should be supported by a dedicated cost-effectiveness study.