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Andreas Rabavilas

Publications and source records attributed to Andreas Rabavilas.

12 recordsLinked to original sources
PubMed2005

Preattentive deficits in developmental disorders of scholastic skills.

Working memory deficiency has been implicated in developmental disorders of scholastic skills. The auditory P50 component of event-related potentials reflecting preattentive processing was investigated in 38 children with developmental disorders of scholastic skills and 19 sibling control children, as elicited during a working memory test. The P50 was evoked by two tones of low and high frequency (500 Hz and 3000 Hz). The group with developmental disorders of scholastic skills showed prolonged P50 latency induced by the low tone, located at the frontal area. The amplitude of P50 induced by the low tone exhibited significantly negative associations with both age and memory performance, whereas age and memory performance were associated positively. These findings indicate that preattentive processing deficits may be implicated not only in auditory cognition but also in developmental disorders of scholastic skills.

Acoustic Stimulation↗
PubMed2005

Reinforced spatial alternation as an animal model of obsessive-compulsive disorder (OCD): investigation of 5-HT2C and 5-HT1D receptor involvement in OCD pathophysiology.

BACKGROUND: This study introduces a laboratory model of compulsive behavior based on persistence in the context of rewarded spatial alternation. METHODS: Rats were screened for spontaneous persistence during T-maze reinforced alternation. Experiment 1: One high and one low spontaneous persistence group (n = 8) received 20 injections of fluoxetine, a matched pair saline, both followed by 4 days of meta-chlorophenylpiperazine (mCPP) challenge. Experiment 2: Five matched groups of rats (n = 9) received pretreatment (20 injections) with fluoxetine, mCPP, desipramine, diazepam or saline, followed by 4 days of mCPP challenge (fluoxetine in mCPP group). After washout, animals received 2 days of naratriptan, followed by another 2-day mCPP challenge. RESULTS: In both experiments mCPP significantly increased persistence in saline controls. Fluoxetine also acutely increased persistence scores: after a gradual return to baseline, these scores showed tolerance to mCPP. Experiment 1: This pattern was significant in high but not low initial persistence groups. Experiment 2: Fluoxetine and mCPP showed cross-tolerance. Neither desipramine nor diazepam protected against mCPP challenge. Persistence scores returned to baseline during washout and naratriptan and were thereafter increased by another mCPP challenge in all but the fluoxetine and mCPP groups, suggesting 5-HT2C receptor mediation. CONCLUSIONS: This model is based on spontaneous persistence behavior showing pharmacological responses concordant with those of compulsive symptomatology.

Animals↗
PubMed2005

Psychophysiological differences in schizophrenics with and without delusional misidentification syndromes: a P300 study.

There is a debate on whether delusional misidentification syndromes (DMSs) and schizophrenia are distinct disorders. Information-processing deficits have been found in both. Since the P300 component of event-related potentials (ERPs) reflects attention and working memory (WM) mechanisms, the P300 elicited during a WM test was studied in schizophrenic patients with DMS in comparison to schizophrenic patients without DMS and controls. Nine schizophrenic patients with DMS, 11 without DMS and 11 healthy controls were tested with a computerized version of the digit span test of the Wechsler batteries. Auditory ERPs were measured during the anticipatory period of the test. P300 amplitude in prefrontal areas was found to be significantly reduced in schizophrenics without DMS and markedly less in DMS patients compared to controls. P300 latency in the central midline brain region was significantly prolonged in DMS patients compared to the other groups. Memory performance was significantly reduced in both patient groups as compared to healthy controls. The results may indicate abnormalities in both allocation of attentional resources and automatic orienting in schizophrenic patients with DSM. In contrast, even though schizophrenic patients without DMS exhibit partial similarities with patients suffering from DMS, they show excessive reduction of P300 amplitude located at the left frontal area. Future studies might clarify these issues.

Acoustic Stimulation↗
PubMed2005

The diagnostic value of tau protein, beta-amyloid (1-42) and their ratio for the discrimination of alcohol-related cognitive disorders from Alzheimer's disease in the early stages.

BACKGROUND: Chronic and heavy alcohol abuse or dependence may result in impaired cognition and dementia. The increased risk of Alzheimer's disease (AD) in older individuals interferes with the differential diagnosis, especially when dealing with elderly patients with a long history of alcohol abuse. The aim of the present study was to evaluate the diagnostic value of the putative cerebrospinal fluid (CSF) biomarkers tau, beta-amyloid 1-42 (Abeta42) and their ratio in differentiating alcohol related cognitive disorder (ARCD) from AD. METHODS: Double-sandwich ELISA (Innotest htau antigen and beta-Amyloid (1-42), Innogenetics) were used to quantify the above markers in a total of 20 patients with ARCD, 33 AD patients with mild to moderate dementia and 50 mentally intact subjects. RESULTS: Tau protein successfully differentiated AD from normal ageing with 96% specificity and 93.9% sensitivity and from ARCD with 95% specificity, and 87.9% sensitivity. Abeta42 alone had a specificity of 88% and a sensitivity of 69.7% in differentiating AD from normal ageing, while the corresponding values for differentiating AD from ARCD were 80% and 84.8% respectively. The tau/Abeta42 ratio was better than tau alone for differentiating AD from normal ageing (specificity 94%, sensitivity 97%) and better than any of the candidate markers alone, for differentiating AD from ARCD (specificity 100%, sensitivity 97%). CONCLUSIONS: The combined use of CSF tau and Abeta42 may be a useful tool in the differential diagnosis of ARCD from AD, especially in the early stages, where diagnostic uncertainty is greater.

Aging↗
PubMed2004

Mirtazapine and venlafaxine in the management of collateral psychopathology during alcohol detoxification.

Symptoms of anxiety and depression are common in a large proportion of alcohol-abusing/dependent individuals during alcohol detoxification. The aim of this study was to examine the impact of a combined psychotherapeutic-psychopharmacological (either with mirtazapine or venlafaxine) treatment of these symptoms during the early withdrawal phase of alcohol compared to a group treated only with psychotherapy. A total of 60 alcohol-dependent/abusing subjects randomly assigned to three groups (psychotherapy, psychotherapy plus mirtazapine, psychotherapy plus venlafaxine) were studied. Assessment of psychopathology and global functioning throughout a 4-5-week detoxification period was done by the Hamilton Anxiety Rating Scale (HARS), the Hamilton Depression Rating Scale (HDRS), and the Global Assessment Scale (GAS). At baseline, high scores of anxiety and depression were recorded (HARS: controls: 33.1+/-7.8, mirtazapine: 33.2+/-12.6, venlafaxine: 36.6+/-5.4; HDRS: controls: 39.5+/-7.4, mirtazapine: 37.9+/-7.8, venlafaxine: 41.9+/-4.5). A marked improvement (p<0.000) was evidenced in all groups by the end of the detoxification period. However, patients on mirtazapine improved significantly more compared to the other two groups (HARS: controls: 9.6+/-7.6, mirtazapine: 4.3+/-4.4*, venlafaxine: 7.2+/-4.1, *p=0.011; HDRS: controls: 8.6+/-7.9, mirtazapine: 3.8+/-3.2*, venlafaxine: 8.2+/-3.5, *p=0.017; GAS: controls: 79.5+/-9.4, mirtazapine: 87.5+/-5.5**, venlafaxine: 83.0+/-8.0, **p=0.006). It is concluded that addition of mirtazapine, but not venlafaxine, to a standard psychotherapy-oriented alcohol detoxification treatment may facilitate the detoxification process by minimizing psychological discomfort. Consequently, it may prove to be a facilitator for the long-term abstinence from alcohol.

Adult↗
PubMed2004

P300 alterations in schizophrenic patients experiencing auditory hallucinations.

RATIONALE: Attentional deficits have been implicated in the pathophysiology of auditory hallucinations in schizophrenia. Since the latency of the P300 component of event-related potentials (ERPs) is considered to be a sensitive measure of stimulus classification speed, while its amplitude-a measure of attentional resource allocation when memory updating is engaged, the present study focuses on the comparison of P300 between healthy subjects and schizophrenic patients experiencing auditory hallucinations and treated with clozapine and olanzapine. METHODS: The auditory P300 was assessed during the anticipatory period of a short memory test, in 16 male hallucinated schizophrenic patients and 13 male normal subjects matched for age and educational level. The patients were reexamined under identical conditions when their hallucinations had resolved following treatment with clozapine (8 patients) and olanzapine (8 patients). RESULTS: The patients with hallucinations exhibited significantly reduced P300 amplitude at leads Fp1, F3, (C3-T5)/2, F4, Cz and Fz, when compared to the normal controls and at leads Fp1, F3, F4, (C4-T6)/2, C4, P4, Cz and Fz when compared to themselves during the remission phase. However logistic regression models revealed that the most important leads, differentiating the patient group before treatment either with the healthy controls, or with itself after treatment, were that at the left temporoparietal and at the left prefrontal area. Memory performance of the patient group, even after treatment and in spite of its significant improvement, remained significantly less than that of healthy controls. both antipsychotic agents had similar effects on the p300 amplitude and memory performance. CONCLUSIONS: These findings indicate that auditory hallucinations in schizophrenia manifest abnormal aspects of attention, mediated by a distributed network involving or affecting the left temporoparietal and left prefrontal area. Additionally, the present study points to an improvement of attentional function in schizophrenic patients experiencing auditory hallucinations, both in the clozapine group but also in the olanzapine group.

Adult↗
PubMed2003

Do atypical antipsychotics fail to exert cognitive sparing effects?

The aim of the study was to investigate patterns of the P600 component of event-related potentials (ERPs) elicited during a working memory test in 16 male schizophrenic patients experiencing auditory hallucinations before and after treatment with clozapine and olanzapine, and 13 male normal subjects matched for age and educational level. Before treatment, patients showed significantly reduced P600 amplitudes on the right parietal region compared with controls, and when in remission also showed significantly reduced P600 amplitudes located on the right parietal and temporofrontal areas, compared both to themselves before treatment and to normal controls. The patient's memory performance before and after treatment remained significantly lower than that of healthy controls. These findings may indicate that auditory hallucinations in schizophrenia are associated with impaired synchronization of the processes related to target detection, as reflected by the P600. The present study also casts doubts regarding the cognitive sparing effect of atypical antipsychotics, despite the fact that they mediate symptom improvement.

Adult↗
PubMed2003

Obsessive-compulsive symptoms induced by atypical antipsychotics. A review of the reported cases.

Atypical antipsychotics (APs) are now widely in use in clinical practice. They exert a beneficial effect in patients with schizophrenic disorders, including cases resistant to traditional APs and negative symptoms. They have also enhanced the ratio of therapeutic efficacy to adverse effects. Atypical APs, mainly risperidone and olanzapine, have been used as adjunctive treatment in (selective) serotonin reuptake inhibitor [(S)SRI]-refractory cases with obsessive symptoms. However, de novo emergence or exacerbation of obsessive-compulsive (OC) symptoms during treatment with clozapine, risperidone, olanzapine and quetiapine has been described in the literature. The reported cases and the possible pathogenetic mechanisms involved in their occurrence are discussed and reviewed.

Antipsychotic Agents↗
PubMed2003

Do obsessive-compulsive patients and abstinent heroin addicts share a common psychophysiological mechanism?

BACKGROUND/AIM: Working memory (WM) and attentional deficits have been implicated in the pathophysiology of both obsessive-compulsive disorder (OCD) and opioid addiction. The P300 component of event-related potentials (ERPs) is considered as an index of on-line updating of WM and/or attentional operations involved in this function. The present study aimed at comparing the P300 elicited during a WM test in patients with prolonged heroin abstinence, those with OCD and healthy controls, in order to demonstrate possibly common underlying psychophysiological mechanisms. METHODS: The P300 component was evaluated during the anticipatory period of a WM test in 20 patients characterized by a past history of opioid dependence (6 months abstinence), in 18 OCD patients, and 20 healthy subjects matched for age, sex and educational level. RESULTS: The two patient groups showed a considerable reduction of the P300 amplitudes, located at the right frontal area as compared with healthy controls. The abstinent heroin addicts exhibited a significantly lower P300 amplitude at central frontal areas and a significantly higher P300 amplitude at the left occipital region relative to the other two groups. Furthermore, the abstinent group showed a notable delay of P300 latency relative to controls and OCD patients at the right occipital region. Moreover, the OCD patients manifested a significant prolongation of P300 located at the central prefrontal area, relative to addicts and healthy controls. CONCLUSIONS: These findings point to considerable WM and/or attentional deficits in the long-term abstinent syndrome of heroin misuse and OCD associated with distributed and prefrontal cortical circuits, respectively. Furthermore, the present findings suggest that both OCD and long-term abstinent heroin addicts may share a common impairment of WM and/or attention involving or affecting the right prefrontal areas.

Adult↗
PubMed2002

Changes of P300 elicited during a Working Memory test in Individuals with depersonalization-derealization experiences.

BACKGROUND/AIM: The P300 component of Event-Related Potentials (ERPs) is related to fundamental aspects of cognitive functions, such as Working Memory (WM) and attention allocation. Deficits in these domains have been implicated in the pathophysiology of depersonalization-derealization (DD). The present study focused on the P300 elicited during a WM test in transient DD experiences. METHODS: Fifteen subjects with transient DD experiences were matched for age, sex and educational level to an equal number of healthy controls. Both groups were submitted to a computerized version of the digit span Wechsler batteries. P300 was measured during the anticipatory period of this test. All participants completed the Dixon self-rating questionnaire. RESULTS: In relation to the control group, the subjects with transient DD experiences showed significantly decreased amplitudes of P300 at central posterior brain areas. Concerning memory performance, the groups did not differ significantly. CONCLUSIONS: These findings may indicate that subjects with transient DD experiences manifest altered aspects of information processing, as reflected by P300 amplitudes elicited during a WM test. Additionally, P300 might serve as a valuable investigative tool for a more comprehensive understanding of the neurobiological substrate of DD.

Adult↗
PubMedDate not supplied

Interrelationship of hepatic function, thyroid activity and mood status in alcohol-dependent individuals.

BACKGROUND: Alcohol-induced changes in thyroid function may contribute to the development of mood disorders such as depression and anxiety that almost invariably coexist in alcohol-dependent individuals. The aim of the present study was to investigate the severity of liver dysfunction and thyroid activity in correlation with anxiety and depressive-like symptomatology before and after a detoxification period. PATIENTS AND METHODS: In a sample of 100 alcohol-abusing/dependent subjects treated on an in-patient basis according to a standard detoxification protocol, measurements of the serum levels of hepatic enzymes (ASAT, ALAT, gammaGT) and thyroid hormones (T3, T4, TSH) as well as measures of anxiety, depression and global functioning were obtained at baseline and at weekly intervals over the period of 4-5 weeks. RESULTS: After completion of the alcohol detoxification, most measurements returned to normal levels and correlations were observed between the levels of hepatic enzymes and thyroid hormones. Additionally, a significant correlation was obtained between the levels of thyroid hormones and the mood status scales. CONCLUSION: Our results indicated a dysfunction of the hypothalamic-pituitary-thyroid axis in alcohol dependence with possible implications in the diagnosis and treatment of mood disorders associated with alcohol abuse.

Adult↗