Biomedical subjects

Hans M Olbrich

Publications and source records attributed to Hans M Olbrich.

3 recordsLinked to original sources

PubMed2006

Brain activation during craving for alcohol measured by positron emission tomography.

OBJECTIVE: Craving for alcohol is probably involved in acquisition and maintenance of alcohol dependence to a substantial degree. However, the brain substrates and mechanisms that underlie alcohol craving await more detailed elucidation. METHOD: Positron emission tomography was used to map regional cerebral blood flow (CBF) in 21 detoxified patients with alcohol dependence during exposure to alcoholic and non-alcoholic beverages. RESULTS: During the alcohol condition compared with the control condition, significantly increased CBF was found in the ventral putamen. Additionally, activated areas included insula, dorsolateral prefrontal cortex and cerebellum. Cerebral blood flow increase in these regions was related to self-reports of craving assessed in the alcoholic patients. CONCLUSIONS: In this investigation, cue-induced alcohol craving was associated with activation of brain regions particularly involved in brain reward mechanisms, memory and attentional processes. These results are consistent with studies on craving for other addictive substances and may offer strategies for more elaborate studies on the neurobiology of addiction.

Adult↗

PubMed2005

Increased prefrontal and hippocampal glutamate concentration in schizophrenia: evidence from a magnetic resonance spectroscopy study.

BACKGROUND: Glutamatergic dysfunction has been implicated in the pathophysiology of schizophrenia. However, so far there is limited direct evidence of altered in vivo glutamate concentrations in the brains of patients with schizophrenia. To test the hypothesis that altered glutamatergic neurotransmission might play a role in the pathogenesis of schizophrenia, we measured glutamate and glutamine concentrations in the prefrontal cortex and the hippocampus of patients with chronic schizophrenia using high-field magnetic resonance spectroscopy. METHODS: Twenty-one patients with schizophrenia and 32 healthy volunteers were examined clinically and by means of short echo time single voxel magnetic resonance spectroscopy of the dorsolateral prefrontal cortex and the hippocampus. Absolute concentrations of neurometabolites were calculated. RESULTS: Absolute concentrations of glutamate were significantly higher in the prefrontal cortex and the hippocampus in the patient group. Factorial analysis of variance (ANOVA) revealed no significant interactions between duration of schizophrenia, number of hospitalizations, or type of antipsychotic medication and glutamate concentrations. Increased prefrontal glutamate concentrations were associated with poorer global mental functioning. CONCLUSIONS: This is the first study that reports increased levels of glutamate in prefrontal and limbic areas in patients with schizophrenia. Our data support the hypothesis of glutamatergic dysfunction in schizophrenia.

Adult↗

PubMed2002

Assessing cerebral dysfunction with probe-evoked potentials in a CNV task -- a study in alcoholics.

OBJECTIVES: Contrary to event-related potential (ERP) components N1, N2 and P3, slow ERPs have rarely been used in assessing cerebral dysfunction in mental disorders. Focussing on slow waves (SWs) and on patients with mild cerebral dysfunction, we recorded ERPs in alcoholics using a dual task design. METHODS: ERPs to auditory probes presented either 1s before the warning or 1s before the imperative stimulus of a visual contingent negative variation (CNV) paradigm were recorded from 33 scalp electrodes in 27 alcoholics following detoxification and 12 healthy controls. Independent component analysis (ICA) was used to separate potentially overlapping spatial components. RESULTS: In alcoholics compared to controls, probe ERPs showed increased N2, decreased P3 and increased negative SWs of two types appearing pre- and post-P3, respectively. Both negative SWs significantly correlated with neuropsychological indices reflecting verbal intelligence and memory functions. The increase in probe-evoked N1 and P3 potentials during CNV, putatively associated with enhanced cortical excitability, significantly correlated with clinical features of protracted alcohol withdrawal syndrome in alcoholics. CONCLUSIONS: Our experimental approach revealed two types of negative SWs which strongly correlated with neuropsychological deficits of mildly impaired patients. It is suggested that our methods might enhance diagnostic efficiency of ERPs. An electrophysiological measure of protracted alcohol withdrawal might be useful for managing central nervous system dysfunction in alcoholics.

Adult↗