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Biomedical subjects

Piero Amodio

Publications and source records attributed to Piero Amodio.

16 recordsLinked to original sources
PubMed2006

Top-down and bottom-up processes in the extrastriate cortex of cirrhotic patients: an ERP study.

OBJECTIVE: This study aims to evaluate the efficiency of top-down and bottom-up processes in the extrastriate cortex of cirrhotic patients without overt hepatic encephalopathy (HE). METHODS: Reaction times (RTs), accuracy and event-related potentials (ERPs) were recorded during the execution of a visual Simon task in 17 cirrhotic patients and 10 healthy controls. Amplitude and latency of the P1 and N1 (indexes of bottom-up processes) and of the N2pc (index of top-down processes) were measured. RESULTS: Patients were slower than controls, and patients with minimal HE (MHE) were slower than patients without MHE. The distribution analysis of RTs showed that the Simon effect decays with slower RTs in all the groups and that the shape of the distribution was different in MHE patients. No differences were found between cirrhotic patients and controls for P1 and N1 amplitude and latency. In contrast, N2pc latency was delayed in cirrhotic patients compared to controls independently of MHE. CONCLUSIONS: In the extrastriate cortex of cirrhotic patients without HE, top-down processes are altered whereas bottom-up processes are preserved. SIGNIFICANCE: The analysis of exogenous and endogenous visual components of ERPs provides a model to study the functional dissociation between top-down and bottom-up processes inside the extrastriate cortex.

Brain↗
PubMed2006

Olfactory deficits in patients affected by minimal hepatic encephalopathy: a pilot study.

Minimal hepatic encephalopathy (MHE) is the earliest stage of hepatic encephalopathy and is associated with changes in cognitive functions, in electrophysiological parameters, and in cerebral neurochemical/neurotransmitter homeostasis. MHE can be observed in patients with cirrhosis who have no clinical evidence of hepatic encephalopathy (HE). At present, no data are available on a possible olfactory dysfunction in such a syndrome, although the pathophysiology of HE may alter olfactory functions since some of the neurotransmitters impaired in the syndrome are involved in the transmission of olfactory information. In the present paper, we performed a preliminary study aimed at detecting whether identification and recognition odor memory is altered in patients with MHE. Twelve patients diagnosed as MHE on the basis of their scores at the portosystemic encephalopathy (PSE)-syndrome test battery, and 12 age-matched controls were studied. Consistent with the hypothesis, patients performed significantly worse than controls for both odor identification and recognition tasks. In addition, a significant correlation between the two olfactory tests and the PSE-syndrome test score was found. This pattern supports the notion that olfactory alterations related to cognitive dysfunction in patients with MHE may be linked to the pathophysiology of HE.

Aged↗
PubMed2005

Diagnostic tools for the study of vascular cognitive dysfunction in hypertension and antihypertensive drug research.

Arterial hypertension is one of the main risk factors for cerebrovascular diseases, and antihypertensive treatment has significantly reduced their associated mortality. However, morbidity has not been reduced to a similar extent and a still increasing number of patients suffers from recurring strokes and from the disabling consequences of cerebrovascular diseases and develops progressive cognitive impairment. It is still debated to what extent antihypertensive treatment may prevent the development of cognitive dysfunction, due to the lack of a focused approach to vascular cognitive impairment, to the lack of a systematic study of the early phases of dementia, and to the use of diagnostic tests that are not sensitive and specific for a slow onset clinical condition, such as dementia. The aim of the present expert consensus report is to enlist the diagnostic tools that are currently available to assess mild cognitive impairment (MCI) and early dementia and that are sensitive and specific enough to be used in observational, longitudinal, and interventional clinical research studies, aiming to investigate the impact of antihypertensive drugs on vascular dementia (VD).

Animals↗
PubMed2005

Attention dysfunction in cirrhotic patients: an inquiry on the role of executive control, attention orienting and focusing.

Attention alterations are reported in cirrhotics. Aiming at clarifying attention functioning in cirrhotics, an inquiry on the functioning of the anterior (AAS) and the posterior (PAS) attention system was performed. Thirty-six cirrhotics without overt hepatic encephalopathy (24 with EEG or TMT-A alterations) and 16 matched control subjects were enrolled. The AAS was studied by the Stroop task measuring selective attention control, the PAS was studied by the Posner task and the Focus task measuring automatic covert orienting and visual focusing of attention respectively. Cirrhotics presented a task-dependent psychomotor slowing (Stroop > Posner > Focus) with an increased percentage of errors in the incongruent condition of the Stroop task [F(1, 57) = 4.9, p < 0.03]. Class C patients had both a selective slowing [F(1, 33) = 4.3, p < 0.05] and an increased percentage of errors in the incongruent condition [F(1, 34) = 5.1, p < 0.05] compared to Class A-B patients and controls. The patients with an altered EEG performed the Stroop test significantly slowly than those without EEG alterations [F(1, 41) = 8.9, p < 0.01] and with a clear trend for a higher number of errors in the incongruent condition [F(1, 39) = 3.8, p < 0.06]. In contrast, attention orienting and focusing were maintained. In conclusion, the AAS is more sensitive than the PAS to the early stages of hepatic encephalopathy.

Attention↗
PubMed2005

Neurophysiological investigation of hepatic encephalopathy.

The neurophysiological tools used to study hepatic encephalopathy (HE) are the electroencephalogram (EEG) and the evoked potentials (EPs), both exogenous and endogenous. These tools are used (1) to diagnose HE in patients with severe liver disease and mental alteration, (2) to grade overt HE and monitor the effect of treatment for HE, (3) to diagnose minimal HE (4) to predict the occurrence of episodes of overt HE or liver-related death. The rationale for the use of each of these tools together with their theoretical and practical role is reviewed.

Electroencephalography↗
PubMed2005

Impairment of response inhibition precedes motor alteration in the early stage of liver cirrhosis: a behavioral and electrophysiological study.

Abnormality in movement initiation may partially explain psychomotor delay of cirrhotic patients, even in the absence of overt hepatic encephalopathy (HE). Therefore, the aim of this study was to determine the mechanisms of psychomotor delay observed in patients with cirrhosis in the absence of overt HE. Fourteen patients with nonalcoholic cirrhosis and 12 healthy matched control subjects underwent the lateralized readiness potential (LRP) measurement elicited by a visuospatial compatibility task (Simon task). Stimulus-triggered LRPonset reflects the time in which response is selected, while response-triggered LRP onset reflects motor execution. Cirrhotic patients showed delayed reaction times (RTs) compared to controls, particularly those with trial-making test A (TMT-A) or electroencephalogram (EEG) alterations. Stimulus-triggered LRP onset was found to be delayed in cirrhotic patients compared to controls, with a significant Group-versus-Condition interaction, showing a reduced cognitive ability to cope with interfering codes, even in patients without minimal HE (MHE). Response-triggered LRP was found to be delayed only in the patients with TMT-A or EEG alterations. In conclusion, cirrhotic patients without overt HE display a psychomotor slowing, depending first lyon response inhibition and only later accompanied by impaired motor execution.

Data Interpretation, Statistical↗
PubMed2005

Horizontal and vertical Simon effect: different underlying mechanisms?

Reaction times are usually faster when stimulus and response occur at the same location than when they do not, even if stimulus location is irrelevant to the task (Simon effect). This effect was found with both horizontal and vertical stimulus-response arrangements. The same mechanisms have been proposed to be involved in either case. Here, we compared a horizontal and a vertical Simon task by means of a RT time-course analysis of the Simon effect. Also, we analysed the lateralised readiness potential (LRP), an index of covert response-preparation processes. In the horizontal task, the Simon effect decays over time and pre-activation occurs above the motor cortex ipsilateral to the stimulus. In contrast, the Simon effect does not decay over time and no early incorrect LRP deflection is observed in the vertical task. These findings suggest that typical activation accounts can fit only the horizontal Simon effect, while a translation explanation is more suitable for the vertical Simon effect.

Adult↗
PubMed2005

Mood, cognition and EEG changes during interferon alpha (alpha-IFN) treatment for chronic hepatitis C.

BACKGROUND: This study is aim to investigate concurrent long-term psychiatric, cognitive and neurophysiological measures of alpha-IFN neurotoxicity in the treatment of chronic viral hepatitis. METHODS: Twenty patients with HCV hepatitis were enrolled while treated with alpha-IFN (3-6 MU t.i.w. for 6-12 months). Neurotoxicity was evaluated by psychiatric [Hamilton Depression Rating Scale (HAM-D), Hamilton Scale for Anxiety (HAM-A), Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI-Y)], complete cognitive and neurophysiological assessments (EEG spectral analysis, P300). Patients were assessed at baseline (t0), 2 (t1) and 6 months (t2) since the beginning of therapy. RESULTS: Depression scores significantly increased (HAM-D: t0=4.4+/-2.6; t1=8.9+/-3.9, p<0.001; and t2=7.7+/-3.8, p<0.001). A concurrent increase was shown also for anxiety (HAM-A: t0=6.0+/-3.2; t1=9.6+/-4.5, p<0.005; and t2=9.1+/-4.5, p<0.005). Significant neurophysiological effects were also detected: increase of alpha power (p<0.05) in frontal derivations, reduction of the mean dominant frequency (p<0.005) and increase of theta power (p<0.05) in parietal derivations. In contrast, no significant cognitive changes occurred. LIMITATIONS: The study was performed on a relative small sample of patients mainly with observational intentions. Biological data (e.g. blood cytokines samples) are not available: they could have given useful information about biological mechanisms related to the alterations observed. CONCLUSIONS: Alpha-IFN treatment caused a time-dependent induction of symptoms of mild depression, concurrent anxiety and EEG changes. These psychiatric and neurophysiological changes can better explain the pharmacological profile of alpha-IFN and could help to address research on at risk population and, particularly, during pegylated-IFN therapy.

Adolescent↗
PubMed2004

Characteristics of minimal hepatic encephalopathy.

The term minimal hepatic encephalopathy refers to the subtle changes in cognitive function, electrophysiological parameters, cerebral neurochemical/neurotransmitter homeostasis, cerebral blood flow, metabolism, and fluid homeostasis that can be observed in patients with cirrhosis who have no clinical evidence of hepatic encephalopathy. Use of this term emphasizes the fact that the entity of hepatic encephalopathy is a single syndrome with quantitatively distinct features relating to severity. The absence of clinical evidence of hepatic encephalopathy is key to the diagnosis and can only be determined by a detailed assessment of the patients' history and a comprehensive neurological assessment of consciousness, cognitive, and motor function. The neuropsychological features of minimal hepatic encephalopathy point to a disorder of executive functioning, particularly selective attention and psychomotor speed, but other abnormalities may be observed. Alterations in electrophysiological variables have been described; endogenous evoked potentials are, in principle, more likely to reflect the presence of minimal hepatic encephalopathy, since they reflect cognitive phenomena rather than mere stimulus conduction but the specificity of the changes observed is unclear at present. Changes have also been described in the execution of diadochokinetic movements and in the capacity to discriminate flickering light, both of which may have diagnostic potential. The changes observed in cerebral blood flow and metabolism in SPET, PET, and 1H and 31P MRS studies reflect the pathogenic process that underlies the condition rather than providing diagnostic information. Similarly, the morphological brain abnormalities identified in this population, including mild brain oedema, hyperintensity of the globus pallidus and other subcortical nuclei observed in cerebral MR studies, and the central and cortical atrophy observed in neural imaging studies, are unlikely to have diagnostic utility. The presence of minimal hepatic encephalopathy is not without clinical consequence; it has a detrimental effect on health-related quality of life, the ability to perform complex tasks such as driving, and on outcome.

Brain↗
PubMed2004

Methods for diagnosing hepatic encephalopathy in patients with cirrhosis: a multidimensional approach.

There is no "gold standard" for diagnosing hepatic encephalopathy in patients with cirrhosis. In consequence, the presence of this condition, unless floridly overt, is often missed. As a result, the majority of patients are denied the benefits of treatment. There are a number of individual techniques, which access different aspects of cerebral function that can be used, singly or in combination, to provide diagnostic information in this condition, including mental state assessment, psychometric testing, electroencephalography, sensory and cognitive evoked potentials, and neuroimaging. These have been variously applied to the study of hepatic encephalopathy but fundamental differences in the essential aims of the studies, as well as differences in the patient populations and the acquisition and analysis of the data, have made comparisons difficult. Thus, there is no clear consensus as to the sensitivity, specificity, or validity of these tests when used alone or in combination. There are, however, a number of additional methods that could be used to analyze the electrophysiological data, and a number of alternative evoked potentials that could be measured to provide better diagnostic information. In addition, there are a number of techniques, such as critical flicker frequency and smooth pursuit eye movements, which have not yet been applied systematically in this condition and which may provide useful diagnostic information. Clearly the methods for assessing hepatic encephalopathy need to be reviewed, newer methods for analyzing the electrophysiological data and newer techniques for assessing alternative aspects of cerebral function need to be explored for their diagnostic utility. This process should aim at developing a multidimensional diagnostic tool.

Brain↗
PubMed2003

Nutritional supplementation with branched-chain amino acids in advanced cirrhosis: a double-blind, randomized trial.

BACKGROUND & AIMS: The role of oral supplementation with branched-chain amino acids (BCAA) in advanced cirrhosis is far from settled. A nutritional approach might prevent progressive liver failure and improve nutritional parameters and quality of life. METHODS: A multicenter, randomized study comparing 1-year nutritional supplementation with BCAA against lactoalbumin or maltodextrins was performed in 174 patients with advanced cirrhosis. Primary outcomes were the prevention of a combined end point (death and deterioration to exclusion criteria), the need for hospital admission, and the duration of hospital stay. Secondary outcomes were nutritional parameters, laboratory data and Child-Pugh score, anorexia, health-related quality of life, and need for therapy. RESULTS: Treatment with BCAA significantly reduced the combined event rates compared with lactoalbumin (odds ratio, 0.43; 95% confidence interval, 0.19-0.96; P = 0.039) and nonsignificantly compared with maltodextrins (odds ratio, 0.51; 95% confidence interval, 0.23-1.17; P = 0.108). The average hospital admission rate was lower in the BCAA arm compared with control treatments (P = 0.006 and P = 0.003, respectively). In patients who remained in the study, nutritional parameters and liver function tests were, on average, stable or improved during treatment with BCAA and the Child-Pugh score decreased (P = 0.013). Also, anorexia and health-related quality of life (SF-36 questionnaire) improved. Long-term compliance with BCAA was poor. CONCLUSIONS: In advanced cirrhosis, long-term nutritional supplementation with oral BCAA is useful to prevent progressive hepatic failure and to improve surrogate markers and perceived health status. New formulas are needed to increase compliance.

Amino Acids, Branched-Chain↗
PubMed2003

Effect of blood ammonia elevation following oral glutamine load on the psychometric performance of cirrhotic patients.

Oral glutamine challenge is a method to increase blood ammonia and may be used to study the ammonia lowering effect of drugs potentially useful in hepatic encephalopathy (HE). We tested its influence on the psychometric performance of 18 cirrhotic patients without HE. Twelve nonencephalopatic cirrhotic patients were studied before and after glutamine load (20 g in 100 mL tap water) and six patients before and after placebo (100 mL tap water) by using the Number Connection Test (NCT), the Covert Visual Attention Orienting Test (CVAOT), and the Scan Test (SCT). Blood ammonia increased significantly after glutamine (from 79 +/- 34 to 211 +/- 66 microg/dL) but not after placebo (from 94 +/- 41 to 88 +/- 26). No difference in the NCT was found before and after glutamine load or placebo. The CVAOT was similar after glutamine challenge and placebo, nor any interaction between Loads (glutamine or placebo) x Cue position was found, suggesting that glutamine load did not influence attention-orienting. SCT results were also similar after glutamine and placebo, suggesting a lack of influence on the working memory. Glutamine challenge is a safe method to induce hyperammonemia in nonencephalopatic cirrhotic patients and, therefore, to study the efficacy of ammonia lowering treatments.

Administration, Oral↗
PubMed2003

Central nervous system alterations in liver cirrhosis: the role of portal-systemic shunt and portal hypoperfusion.

The role of portal-systemic shunting and portal liver hypoperfusion in the pathophysiology of central nervous system dysfunction (CNSD) of cirrhosis is not yet well defined. It is well known that one of the most important collateral vessels (CVs) is a patent paraumbilical vein (PUV), but there is controversy regarding its clinical significance. We have evaluated the relationships between neuropsychological and EEG alterations, ammonia plasma level (NH4), hepatic function, and portal hemodynamics (Doppler Ultrasound) in 95 cirrhotic patients. Patency, diameter, or flow of PUV or the presence of other CVs were not related to an increased prevalence of neuropsychological or EEG abnormalities. Patients with effective portal flow (EPF = portal flow - PUV flow) lower than 692 mL/min (median) had a significantly higher risk of failing the neuropsychological test, or of having an altered EEG. Low EPF and prothrombin time (<50%), and high NH4 (51 micromol/L) were independent predictors of an abnormal EEG. Considering both low EPF and the numerosity of CVs, only low EPF was found to explain EEG alterations. In conclusion, portal liver hypoperfusion and decreased liver function were associated with an increased risk of CNSD in cirrhotic patients, whereas PUV patency per se was not.

Brain↗
PubMed2002

Variability of trail making test, symbol digit test and line trait test in normal people. A normative study taking into account age-dependent decline and sociobiological variables.

BACKGROUND AND AIMS: The influence of sociobiological variables and aging on the variability of the Trail Making Tests (TMT), the Symbol Digit Substituting Test (SDT), and the Line Trait Test (LTT) in the general healthy populations are not well known. Even less is known about the reliability at re-testing. This study aimed at determining the reference range of these tests, taking into account sociobiological variables and age, and the re-testing effect. METHODS: We studied 300 healthy subjects from 20 to 80 years of age. The sample was derived by the pooling of two samples stratified by age and sex: a randomized sample of 161 subjects collected from the city registers of Padova, and a convenience sample of 139 subjects collected in 20 towns (mainly rural) of Northern Italy. After normalization, data were assayed for the influence of age, education, job, and gender. RESULTS: Age was found to be a significant independent predictor for all the tests, education for all but the LTT, job only for the TMT-B and a geometrical version of the same test (TMT-G) which was proved to be highly correlated with the TMT-B (r=0.80, p<0.01). Job and the interaction age x education level influenced the difference TMT-B minus TMT-A. From the predicting equations, the normative data and the formulas to obtain Z scores for each test were derived. Reliability was lowest for LTT errors (CV=67%), highest for the SDT (13%), whereas the TMT obtained intermediate values (22-33%, depending on the test). CONCLUSIONS: This study provides the most reliable normative data range for the TMT, SDT and LTT to date because it considers important demographic variables such as age, education and job.

Adult↗
PubMed2002

Central nervous system alterations in liver cirrhosis: the role of portal-systemic shunt and portal hypoperfusion.

The role of portal-systemic shunting and portal liver hypoperfusion in the pathophysiology of central nervous system dysfunction of cirrhosis is not yet well defined. It is well known that one of the most important collateral vessels (CV) is a patent paraumbilical vein (PUV) but there is controversy regarding its clinical significance. We have evaluated the relationships between neuropsychological and EEG alterations, ammonia plasma level (NH4), hepatic function, and portal hemodynamics (Doppler Ultrasound) in 95 cirrhotic patients. Patency, diameter, or flow of PUV or the presence of other CV were not related to an increased prevalence of neuropsychological or EEG abnormalities. Patients with effective portal flow (EPF = portal flow - PUV flow) lower than 692 mL/min (median) had a significantly higher risk of failing the neuropsychological test, or of having an altered EEG. Low EPF and prothrombin time (<50%), and high NH4 (> or = 51 micromol/L) were independent predictors of an abnormal EEG. Considering both low EPF and the numerosity of CV, only low EPF was found to explain EEG alterations. In conclusion, portal liver hypoperfusion and decreased liver function were associated with an increased risk of central nervous system dysfunction in cirrhotic patients, whereas PUV patency per se was not.

Brain↗