PubMed Health⌕ Search

Biomedical subjects

Alex Hofer

Publications and source records attributed to Alex Hofer.

At least 19 recordsLinked to original sources
PubMed2007

Neural substrates for episodic encoding and recognition of unfamiliar faces.

Functional MRI was used to investigate brain activation in healthy volunteers during encoding of unfamiliar faces as well as during correct recognition of newly learned faces (CR) compared to correct identification of distractor faces (CF), missed alarms (not recognizing previously presented faces, MA), and false alarms (incorrectly recognizing newly presented faces, FA). Encoding was associated with frontal, occipital/fusiform, thalamic, and cerebellar activation. CR produced activation in frontal and cerebellar regions, whereas CF activated frontal and occipitotemporal regions as well as the thalamus. In contrast, MA was associated with frontal and thalamic activation, and FA with frontal activation. The CR minus CF comparison showed left lateral prefrontal and parietal activation, while no suprathreshold positive signal changes were detected when subtracting the other conditions (CR minus MA, CR minus FA, and vice versa). These results support the view that the successful episodic retrieval of newly learned faces is based on a dorsal visual stream mechanism.

Adult↗
PubMed2006

Brain activation patterns during a selective attention test--a functional MRI study in healthy volunteers and unmedicated patients during an acute episode of schizophrenia.

In a previous functional magnetic resonance imaging (fMRI) study of high functioning outpatients with remitted schizophrenia, we found increased activity compared with healthy subjects across multiple areas of the brain, including the dorsolateral frontal cortex and the anterior cingulate, during a modified Stroop task. The same fMRI procedure was used in this subsequent study to investigate eight unmedicated patients during an acute episode of schizophrenia and eight healthy control subjects. Patients showed a reduced activation in dorsolateral prefrontal, anterior cingulate and parietal regions and a higher activation in temporal regions and posterior cingulate compared to healthy controls. Healthy controls showed a trend towards higher accuracy in the modified Stroop task compared to schizophrenia patients. Treatment with second generation antipsychotics may improve executive performance in patients with schizophrenia and facilitate a normalization of functional hypofrontality after symptomatic improvement.

Acute Disease↗
PubMed2006

The neural regions sustaining episodic encoding and recognition of objects.

In this functional MRI experiment, encoding of objects was associated with activation in left ventrolateral prefrontal/insular and right dorsolateral prefrontal and fusiform regions as well as in the left putamen. By contrast, correct recognition of previously learned objects (R judgments) produced activation in left superior frontal, bilateral inferior frontal, and right cerebellar regions, whereas correct rejection of distractor objects (N judgments) was associated with activation in bilateral prefrontal and anterior cingulate cortices, in right parietal and cerebellar regions, in the left putamen, and in the right caudate nucleus. The R minus N comparison showed activation in the left lateral prefrontal cortex and in bilateral cingulate cortices and precunei, while the N minus R comparison did not reveal any positive signal change. These results support the view that similar regions of the frontal lobe are involved in episodic encoding and retrieval processes, and that the successful episodic retrieval of newly learned objects is mainly based on a frontoparietal network.

Adult↗
PubMed2006

Alterations of glucose metabolism during treatment with clozapine or amisulpride: results from a prospective 16-week study.

Although second-generation antipsychotics have notable benefits as compared to typical antipsychotics, their use has been associated with metabolic disturbances, such as alterations of glucose homeostasis. It is still being debated whether this is a class effect of second-generation antipsychotics. We conducted a prospective, open study comparing body weight, parameters of insulin resistance in schizophrenia patients treated with either clozapine (n = 10) or amisuLpride ( n = 12). All parameters were assessed monthly over a period of 12 to 16 weeks. Body mass index (BMI), fasting serum insulin levels and the Homeostasis Model Assessment (HOMA) index for insulin resistance increased significantly in patients treated with clozapine. None of these parameters increased significantly in patients treated with amisulpride. This study indicates that treatment with clozapine appears to have a higher risk to lead to metabolic disturbances than amisupride.

Adolescent↗
PubMed2006

Sex differences in brain activation patterns during processing of positively and negatively valenced emotional words.

BACKGROUND: Previous studies have suggested that men and women process emotional stimuli differently. In this study, we used event-related functional magnetic resonance imaging (fMRI) to investigate gender differences in regional cerebral activity during the perception of positive or negative emotions. METHOD: The experiment comprised two emotional conditions (positively/negatively valenced words) during which fMRI data were acquired. RESULTS: Thirty-eight healthy volunteers (19 males, 19 females) were investigated. A direct comparison of brain activation between men and women revealed differential activation in the right putamen, the right superior temporal gyrus, and the left supramarginal gyrus during processing of positively valenced words versus non-words for women versus men. By contrast, during processing of negatively valenced words versus non-words, relatively greater activation was seen in the left perirhinal cortex and hippocampus for women versus men, and in the right supramarginal gyrus for men versus women. CONCLUSIONS: Our findings suggest gender-related neural responses to emotional stimuli and could contribute to the understanding of mechanisms underlying the gender disparity of neuropsychiatric diseases such as mood disorders.

Adult↗
PubMed2006

Gender differences in regional cerebral activity during the perception of emotion: a functional MRI study.

Whether men activate different brain regions during various emotions compared to women or whether gender differences exist in transient emotional states has been the subject of only few studies. We used event-related functional magnetic resonance imaging (fMRI) to investigate gender differences during the perception of positive or negative emotions. The experiment comprised two emotional conditions (pleasant/unpleasant visual stimuli) during which fMRI data were acquired. Altogether, 38 healthy volunteers (19 males, 19 females) were investigated. When subtracting the activation values of men from those of women, suprathreshold positive signal changes were detected in the right posterior cingulate, the left putamen and the left cerebellum during positive mood induction, and in bilateral superior temporal gyri and cerebellar vermis during negative mood induction. The subtraction of activation values of women from those of men yielded no significant differences. Our findings suggest gender-related neural responses to emotional stimuli and could contribute to the understanding of mechanisms underlying gender-related vulnerability of the prevalence and severity of neuropsychiatric disorders.

Adult↗
PubMed2006

Language lateralization in unmedicated patients during an acute episode of schizophrenia: a functional MRI study.

In a previous fMRI study of high-functioning outpatients with remitted schizophrenia, we found that healthy subjects and schizophrenia patients showed similar patterns of activation during a verbal fluency task. However, the activation in controls was primarily in Broca's area on the left, while it was more bilateral for schizophrenia patients, implicating a reduced language lateralization in schizophrenia patients. The same fMRI procedure was used in this subsequent study to investigate unmedicated patients during an acute episode of schizophrenia. Schizophrenia patients showed reduced language lateralization in the frontal cortex, because of a more bilateral activation of Broca's area compared with a primarily left hemisphere activation in healthy controls. Furthermore decreased lateralization was correlated to the severity of hallucinations. Although patients with schizophrenia showed a significantly reduced performance on the verbal fluency task when compared with healthy subjects, we were not able to find evidence of decreased language-related activity in the left hemisphere. These results suggest that decreased language lateralization is also evident in unmedicated patients experiencing an acute episode of schizophrenia.

Acute Disease↗
PubMed2006

Association between antipsychotic-induced elevation of liver enzymes and weight gain: a prospective study.

We conducted a prospective, open study in schizophrenia patients treated with second-generation antipsychotics in order to investigate the risk for elevation of liver enzymes and its correlation to antipsychotic-induced weight gain. Body mass index, serum transaminases, plasma serum levels of the antipsychotic used, and blood cell counts were measured weekly during the first 6 weeks of treatment and monthly thereafter. A considerable proportion of subjects showed an increase beyond normal levels of at least one of the measured transaminases. In all but one case, the elevation of liver enzymes was transient. We found a statistically significant correlation between weight gain and liver enzyme elevation. The group of patients that had gained at least 7% of the baseline body weight showed significantly higher increases of transaminases as compared with those who had gained less than 7% weight. We conclude that antipsychotic-induced elevation of liver enzymes is mostly transient and could be associated with weight gain.

Adolescent↗
PubMed2006

Early changes of plasma lipids during treatment with atypical antipsychotics.

Metabolic side effects have been found earlier during treatment with second-generation antipsychotics. Among those disturbances serum lipids are less investigated. We conducted a prospective, open study in schizophrenia patients in order to compare body weight and serum lipids during treatment with amisulpride, ziprasidone, clozapine or olanzapine over a period of 4 weeks. Body mass index, total cholesterol and triglycerides increased in patients treated with clozapine and olanzapine whereas high-density lipoprotein cholesterol decreased in those patients. In patients treated with amisulpride or ziprasidone, we found a decrease in body mass index and total cholesterol whereas high-density lipoprotein cholesterol increased. Our results indicate that treatment with ziprasidone and amisulpride is more favourable than treatment with clozapine and olanzapine with respect to the risk to induce weight gain and hyperlipidaemia. These results are important with regard to the increased risk for cardiovascular complications in patients with schizophrenia.

Adolescent↗
PubMed2005

Correlates of subjective and functional outcomes in outpatient clinic attendees with schizophrenia and schizoaffective disorder.

Outcome in schizophrenia is multidimensional and, thus, consists of clinical,humanitarian, rehabilitative and cost domains. Accordingly, recovery is conceptualized as the ability to function in the community, socially and vocationally, as well as being relatively free of disease-related psychopathology. The present cross-sectional study examined the relationship of premorbid functioning, psychopathology, insight, attitudes toward medication and side-effects, as well as sociodemographic factors with treatment outcomes in terms of quality of life (QOL) and psychosocial functioning among 60 regular attendees of a specialized schizophrenia outpatient clinic. Both insight into the illness as well as attitudes toward treatment indicated satisfactory compliance. Premorbid school and social functioning were positively correlated with actual employment status, and premorbid social functioning was further positively correlated with QOL and global functioning. Attitudes toward treatment were positively associated with global QOL, and with the patients' living situation. Both positive and negative symptoms as well as asthenia were negatively associated with QOL, while cognitive symptoms negatively influenced occupational functioning. Older patients lived independently and/or in a partnership more often, but had a lesser likelihood of competitive employment. Our observations suggest that subjective and functional outcomes in highly compliant patients are mainly predicted by psychopathological symptoms and unchangeable sociodemographic variables.

Activities of Daily Living↗
PubMed2005

Patient outcomes in schizophrenia I: correlates with sociodemographic variables, psychopathology, and side effects.

OBJECTIVE: The present cross-sectional study examined the relationships of psychopathology, side effects, and sociodemographic factors with treatment outcomes in terms of patients' quality of life (QOL), functioning, and needs for care. METHOD: Sixty outpatients with chronic schizophrenia who had been treated with either clozapine or olanzapine for at least 6 months were investigated. RESULTS: Most psychopathological symptoms as well as psychic side effects, weight gain, and female sex were associated with lower QOL, while cognitive symptoms correlated with better QOL. Female sex, cognitive symptoms, and parkinsonism negatively influenced occupational functioning, and negative symptoms determined a lesser likelihood of living independently. Age, education, depression/anxiety, negative symptoms, and psychic side effects were predictors of patients' needs for care. CONCLUSION: Our results highlight the complex nature of patient outcomes in schizophrenia. They reemphasize the need of targeting effectiveness, i.e. both symptomatic improvement as well as drug safety, in such patients.

Adult↗
PubMed2005

Patient outcomes in schizophrenia II: the impact of cognition.

BACKGROUND: Cognitive dysfunction is increasingly considered to be the strongest clinical predictor of poor long-term outcome in schizophrenia. Associations have been found between the severity of cognitive deficits and social dysfunction, impairments in independent living, occupational limitations, and disturbances in quality of life (QOL). METHODS: In this cross-sectional study, the relationships of cognitive deficits and treatment outcomes in terms of QOL, needs, and psychosocial functioning were examined in 60 outpatients with schizophrenia who had a duration of illness over 2 years and had been treated with either clozapine or olanzapine for at least 6 months. RESULTS: The present study suggests that cognitive functioning might be a predictor of work functioning/independent living outcome in stabilized patients with schizophrenia: deficits of visual memory and working memory were negatively associated with occupational functioning, and older patients lived independently and/or in a stable partnership more often. The patients' assessments of QOL and needs for care did not show any significant associations with cognitive functioning. DISCUSSION: These findings suggest that cognitive functioning is a key determinant of work functioning/independent living for stable outpatients with schizophrenia.

Adult↗
PubMed2005

QTc variability in schizophrenia patients treated with antipsychotics and healthy controls.

QTc prolongation is associated with the administration of some antipsychotics but the QTc interval is also known to vary physiologically. There is little published evidence about changes in QTc variability during treatment with antipsychotics. In this prospective investigation, we analyzed ECGs in 61 patients suffering from a schizophrenic disorder who were treated with different antipsychotics and 31 sex- and age-matched healthy controls. We found no differences in QTc intervals nor in QTc variability between patients and controls. Our results raise the question of the clinical relevance of a single ECG for diagnostics of cardiac complications in schizophrenia patients and suggest the need to conduct ECG monitoring in patients at high risk for cardiac complications during antipsychotic treatment.

Adult↗
PubMed2005

Osteoporosis in patients with schizophrenia.

OBJECTIVE: Osteoporosis is regularly mentioned as a possible consequence of treatment with prolactin-increasing antipsychotic medications, but little is known about the prevalence and the degree of loss of bone mineral density in patients suffering from schizophrenia. The authors' goals were to investigate the association between schizophrenia and a decrease in bone mineral density and to get more insight into potential underlying pathophysiological mechanisms. METHOD: In a cross-sectional study, the authors used dual x-ray absorptiometry to determine bone mineral density of 75 inpatients and outpatients suffering from schizophrenia. All patients had been treated with antipsychotics for at least 1 year, and only patients between the ages of 19 and 50 were studied to exclude patients with age-related idiopathic osteoporosis. RESULTS: In men but not women with schizophrenia, bone mineral density was significantly lower than normal in the lumbar region. A comparison of loss of bone mineral density in male and female patients showed significant differences between the sexes. Bone mineral density showed a negative correlation with negative symptoms and Positive and Negative Syndrome Scale total score and a positive correlation with 25-hydroxy-vitamin D3 levels and body mass index in male patients. In female patients, a positive correlation between body mass index and bone mineral density was found. Exposure to prolactin-increasing antipsychotics was not related to bone mineral density. CONCLUSIONS: The male patients with schizophrenia in this study suffered from low bone density. This finding as well as other reports lend support to directing more attention to bone metabolism in patients with schizophrenia, although there is no universally accepted screening policy to identify individuals at high risk for osteoporosis.

Absorptiometry, Photon↗