Biomedical subjects

Daniel Schuepbach

Publications and source records attributed to Daniel Schuepbach.

9 recordsLinked to original sources

PubMed2006

Association between two distinct executive tasks in schizophrenia: a functional transcranial Doppler sonography study.

BACKGROUND: Schizophrenia is a severe mental disorder involving impairments in executive functioning, which are important cognitive processes that can be assessed by planning tasks such as the Stockings of Cambridge (SOC), and tasks of rule learning/abstraction such as the Wisconsin Card Sorting Test (WCST). We undertook this study to investigate the association between performance during separate phases of SOC and WCST, including mean cerebral blood flow velocity (MFV) measurements in chronic schizophrenia. METHODS: Functional transcranial Doppler sonography (fTCD) was used to assess bilateral MFV changes in the middle (MCA) and anterior (ACA) cerebral arteries. Twenty-two patients with chronic schizophrenia and 20 healthy subjects with similar sociodemographic characteristics performed SOC and WCST during fTCD measurements of the MCA and the ACA. The SOC was varied in terms of easy and difficult problems, and also in terms of separate phases, namely mental planning and movement execution. The WCST performance was assessed separately for maintaining set and set shifting. This allowed us to examine the impact of problem difficulty and the impact of separate phases of a planning task on distinct intervals of WCST. Simultaneous registration of MFV was carried out to investigate the linkage of brain perfusion during the tasks. RESULTS: In patients, slowing of movement execution during easy problems (SOC) was associated with slowing during maintaining set (WCST) (P < 0.01). In healthy subjects, faster planning and movement execution during predominantly difficult problems were associated with increased performance of WCST during set shifting (P < 0.01). In the MCA, patients showed a significant and positive correlation of MFV between movement execution and WCST (P < 0.01). CONCLUSION: The results of this study demonstrate performance and brain perfusion abnormalities in the association pattern of two different tasks of executive functioning in schizophrenia, and they support the notion that executive functions have a pathological functional correlate predominantly in the lateral hemispheres of the brain. This study also underpins the scientific potential of fTCD in assessing brain perfusion in patients with schizophrenia.

Adult↗

PubMed2005

Voluntary vs. involuntary hospital admission in acute mania of bipolar disorder: results from the Swiss sample of the EMBLEM study.

BACKGROUND: Patients with acute mania in bipolar disorder require pharmacological treatment to reduce symptoms. In addition, it is recognised that admission status is a clinically relevant aspect of bipolar disorder. There is, however, a lack of published data assessing the association of admission status with clinical or functional outcomes. The European-Mania-in-Bipolar-Longitudinal-Evaluation-of-Medication (EMBLEM) study has been designed to describe outcomes associated with medication therapies. Baseline data from this study are now available and we used these data to examine the characteristics of patients with acute mania in the Swiss EMBLEM cohort who were admitted involuntary and voluntary, respectively, and their functional and clinical status. METHODS: Ninety-five patients with an acutely manic or mixed episode of bipolar disorder were included in the Swiss cohort of the study. Patients' history, psychosocial functioning, clinical measures of mania and depression, pharmacological and compliance variables were assessed. Statistical methods comprised univariate analyses of variance and logistic regression analyses to elucidate associations between variables of interest. RESULTS: Patients with involuntary hospital admission (n = 55) were more aggressive and had less insight. They had a more frequent history of substance abuse and were less likely to take anticonvulsants or lithium. Furthermore, these patients showed lower compliance, which also guided physicians' decision on pharmacotherapy. LIMITATION: The EMBLEM study had an observational and non-interventional design; therefore it was not possible to compare treatment groups by means of stringent between-group analyses. However, a main target of this study was to gather clinically relevant information on outcomes of acute mania associated with currently available medication therapies. CONCLUSIONS: Involuntary admission status was significantly associated with clinical status, especially aggression and also compliance. Admission status in bipolar patients plays a clinically important role.

Acute Disease↗

PubMed2005

Lateralization of cerebral hemodynamics during Wisconsin Card Sorting Test: a functional transcranial Doppler sonography study.

OBJECTIVE: Studies on lateralization of cerebral metabolism during Wisconsin Card Sorting Test (WCST), a well-known paradigm of category learning, have shown mixed results. Moreover, sorting dimension (number, color and shape) is a cofounder of laterality in WCST. Functional transcranial Doppler sonography (fTCD) has a high temporal resolution and allows the measurement of mean cerebral blood flow velocity (CBFV) in the middle (MCA) and anterior cerebral arteries (ACA), which supply lateral and medial parts of the frontal and parietal lobes, respectively. We used fTCD to investigate CBFV changes occurring in both MCA and ACA during WCST and different sorting dimensions. METHODS: Twenty-one subjects underwent twice two distinct phases of the WCST, namely maintaining a rule (maintaining set) and searching for a new rule (set shifting), during bilateral fTCD of the MCA and ACA. RESULTS: There was a left-sided dominance of CBFV during maintaining set and set shifting in the MCA. CBFV was not associated with test performance. The sorting dimension number caused the highest CBFV increase in both MCA and ACA during maintaining set, and the sorting dimension shape caused lowest CBFV decrease in both MCA during set shifting. CONCLUSIONS: This study confirms results that cerebral blood flow (CBF) lateralizes to the left side during WCST. The 3 sorting dimensions provoked distinct processing speed during maintaining set and set shifting, but caused no effect on hemispheric lateralization. SIGNIFICANCE: Functional transcranial Doppler sonography can be used to assess CBFV during WCST and different sorting dimensions, and the latter modulate reaction time and cerebral hemodynamics.

Adult↗

PubMed2004

Cerebral hemodynamics and processing speed during category learning.

The Wisconsin Card Sorting Test (WCST) is a commonly used paradigm of category learning with two alternating and distinct processes, maintaining set and set shifting that have been characterized by functional transcranial Doppler sonography (fTCD) of the basal cerebral arteries. Further, repeated WCST administrations resulted in improved speed of solution. This study addressed the question of whether optimised speed during maintaining set or set shifting is associated with changes of cerebral hemodynamics as measured by bilateral fTCD. During maintaining set, improved speed was associated with increased peak mean cerebral blood flow velocity (CBFV) of the anterior cerebral arteries. These results suggest a common functional substrate between optimised speed of solution and cerebral hemodynamics during maintaining set.

Adult↗

PubMed2004

Pretreatment and longitudinal studies of neuropsychological deficits in antipsychotic-naïve patients with schizophrenia.

The early course of neuropsychological dysfunction in schizophrenia and the impact of treatment on these deficits need to be better specified. A sample of 45 patients with schizophrenia underwent five neuropsychological evaluations from prior to treatment with antipsychotic treatment through a 2-year follow-up period. A comparison sample of 33 matched healthy individuals underwent neuropsychological evaluations at similar time points. At baseline, a generalized deficit across cognitive domains was evident for the schizophrenia sample. After 6 weeks of treatment, patients showed modest improvements in visual memory and visual perception, but a decline in verbal memory. Verbal memory performance returned to baseline levels by the 6-month follow-up while deficits in other neuropsychological domains persisted throughout the 2-year period. Relatively static and generalized neuropsychological dysfunction, evident from illness onset, is consistent with neurodevelopmental rather than neurodegenerative models of schizophrenia.

Adult↗

PubMed2004

Early treatment-induced improvement of negative symptoms predicts cognitive functioning in treatment-naive first episode schizophrenia: a 2-year followup.

Studying neuroleptic-naive first episode schizophrenia is a strategy for investigating clinical and neuropsychological abnormalities at a very early phase of the disease without confounding influences of illness duration and medication effects. We examined the clinical and neuropsychological time course over 2 years in 32 neuroleptic-naive first episode patients (20 males, 12 females) and 21 healthy individuals with similar sociodemographic characteristics. Early treatment-induced reduction of negative symptoms predicted superior cognitive performance throughout followup in the domains of verbal fluency, attention, and non-verbal learning and memory. There were no associations between psychotic or disorganized symptoms and cognitive variables. These findings suggest an important relationship between treatment efficacy of antipsychotic medication and the longer term course of cognitive deficits in schizophrenia.

Adolescent↗

PubMed2004

Relationships between cognitive and neurological performance in neuroleptic-naïve psychosis.

The authors explored relationships between neuropsychological performance and neurological exam abnormalities in 86 never-medicated patients with nonorganic psychosis (59 with schizophrenia or schizoaffective disorder) and 51 healthy subjects. Assessments include a reliable subset of the Neurological Evaluation Scale (rNES) and several neuropsychological tests of attention, executive function, memory, and current and premorbid intelligence. Principal components analysis of the rNES yielded two main factors. Of these, CogPer (consisting of more cognitively demanding perceptual tasks) showed stronger relationships than RepMot (consisting of repetitive manual motor tasks) to neuropsychological measures. Customarily, frontal neuropsychological tasks also relate more strongly to CogPer than to RepMot. Approximately one-half of the variability in these cognitive and neurological assessments is shared.

Adult↗

PubMed2002

Temporal modulation of cerebral hemodynamics under prefrontal challenge in schizophrenia: a transcranial Doppler sonography study.

Transcranial Doppler sonography (TCD) is a non-invasive method to assess cerebral blood flow velocity (CBFV) and hence cerebral blood flow during cognitive activation. Major cognitive dysfunctions have been consistently reported in patients with schizophrenia, and important deficits have been observed with respect to prefrontal functions. However, prefrontal activation in schizophrenics has not been investigated with TCD despite its potential to examine short-term changes of cerebral blood flow. The Wisconsin Card Sorting Test (WCST) and the Tower of Hanoi puzzle were administered to 11 right-handed schizophrenics and 20 healthy controls. The middle and anterior cerebral arteries were pairwise insonated. Schizophrenics showed decreased CBFV during the initial phase of both prefrontal functions and the steady-state phase of the Tower of Hanoi. In healthy controls, there was a succession of three significantly different phases of mean CBFV during the Tower of Hanoi, and there was no such modulation in schizophrenics. Immediately after category shift in the WCST, there was an increase of mean CBFV in healthy controls, but not in schizophrenics. In conclusion, transcranial Doppler sonography was able to detect differing specific alterations of CBFV during two prefrontal tasks in healthy controls and patients with schizophrenia. Importantly, the results of this study imply a degraded pattern of CBFV changes over time in schizophrenia during prefrontal activation.

Adult↗

PubMed2002

Negative symptom resolution and improvements in specific cognitive deficits after acute treatment in first-episode schizophrenia.

Patients with first-episode schizophrenia show significant cognitive impairments even at this early phase of their illness. Antipsychotic medication improves clinical symptomatology, but the effectiveness of this treatment on neuropsychological deficits remains unclear. We investigated clinical symptom and neuropsychological performance change in 34 unmedicated first-episode psychotic patients (17 males, 17 females) from the time prior to treatment until 33.6+/-11.3 days after treatment initiation at which time patients demonstrated meaningful recovery from psychosis. Twenty-four matched healthy subjects were also studied. Performance in most neuropsychological functions (language skills, attention, nonverbal learning and reasoning, motor speed) remained stable for the group as a whole. However, reduction in negative symptoms was significantly correlated with performance increases in verbal fluency and attention. Higher negative symptom recovery was associated with improvement of cognitive performance to levels approaching those of healthy subjects, whereas low or no negative symptom improvement was associated with stable or decreased cognitive performance. Reduction in positive symptoms was not associated with change in cognitive abilities. These findings suggest a linkage between early, treatment-induced improvements in negative symptoms and reductions in distinct cognitive deficits.

Acute Disease↗