Biomedical subjects

Lukas Pezawas

Publications and source records attributed to Lukas Pezawas.

13 recordsLinked to original sources

PubMed2006

Neural mechanisms of genetic risk for impulsivity and violence in humans.

Neurobiological factors contributing to violence in humans remain poorly understood. One approach to this question is examining allelic variation in the X-linked monoamine oxidase A (MAOA) gene, previously associated with impulsive aggression in animals and humans. Here, we have studied the impact of a common functional polymorphism in MAOA on brain structure and function assessed with MRI in a large sample of healthy human volunteers. We show that the low expression variant, associated with increased risk of violent behavior, predicted pronounced limbic volume reductions and hyperresponsive amygdala during emotional arousal, with diminished reactivity of regulatory prefrontal regions, compared with the high expression allele. In men, the low expression allele is also associated with changes in orbitofrontal volume, amygdala and hippocampus hyperreactivity during aversive recall, and impaired cingulate activation during cognitive inhibition. Our data identify differences in limbic circuitry for emotion regulation and cognitive control that may be involved in the association of MAOA with impulsive aggression, suggest neural systems-level effects of X-inactivation in human brain, and point toward potential targets for a biological approach toward violence.

Alleles↗

PubMed2005

Actigraphy in patients with seasonal affective disorder and healthy control subjects treated with light therapy.

BACKGROUND: Abnormalities of the circadian rest-activity cycle are hypothesized to accompany the clinical picture of seasonal affective disorder (SAD). The purpose of this study was to investigate if bright light therapy (BLT) is able to reverse these disturbances. METHODS: Seventeen SAD outpatients and 17 sex- and age-matched healthy control subjects were treated with BLT administered in the morning for 4 weeks. Activity levels were measured with wrist actigraphy. RESULTS: SAD patients had 33% lower total (p = .031) and 43% lower daylight activity (p = .006) in week 1 compared with control subjects. The relative amplitude of the sleep-wake cycle was attenuated by 6% in patients (p = .025); they were phase delayed by 55 minutes (p = .023) and had significantly lower sleep efficiency (p = .030). Total (p = .002) and daylight activity (p = .001) increased after 4 weeks of treatment in SAD patients. Moreover, BLT led to increase of relative amplitude (p = .005), advance of delayed rhythms (p = .036), and improved sleep efficiency (p = .011) in patients. Intradaily stability, measuring the strength of coupling of the rhythm to external zeitgebers, increased by 9% both in patients and healthy control subjects (p = .032). CONCLUSIONS: Treatment with BLT normalizes disturbed activity patterns and restores circadian rhythms in SAD patients. BLT might also stabilize the circadian rhythm in nondepressed individuals during the fall-winter season.

Activity Cycles↗

PubMed2005

Variation in DISC1 affects hippocampal structure and function and increases risk for schizophrenia.

Disrupted-in-schizophrenia 1 (DISC1) is a promising schizophrenia candidate gene expressed predominantly within the hippocampus. We typed 12 single-nucleotide polymorphisms (SNPs) that covered the DISC1 gene. A three-SNP haplotype [hCV219779 (C)-rs821597 (G)-rs821616 (A)] spanning 83 kb of the gene was associated with schizophrenia in a family-based sample (P = 0.002). A common nonconservative SNP (Ser704Cys) (rs821616) within this haplotype was associated with schizophrenia (P = 0.004). Based on primary expression of DISC1 in hippocampus, we hypothesized that allelic variation at Ser704Cys would have a measurable impact on hippocampal structure and function as assayed via specific hippocampus-related intermediate phenotypes. In addition to overtransmission in schizophrenia, the Ser allele was associated with altered hippocampal structure and function in healthy subjects, including reduced hippocampal gray matter volume and altered engagement of the hippocampus during several cognitive tasks assayed with functional magnetic resonance imaging. These convergent data suggest that allelic variation within DISC1, either at Ser704Cys or haplotypes monitored by it, increases the risk for schizophrenia and that the mechanism of this effect involves structural and functional alterations in the hippocampal formation.

Adult↗

PubMed2005

5-HTTLPR polymorphism impacts human cingulate-amygdala interactions: a genetic susceptibility mechanism for depression.

Carriers of the short allele of a functional 5' promoter polymorphism of the serotonin transporter gene have increased anxiety-related temperamental traits, increased amygdala reactivity and elevated risk of depression. Here, we used multimodal neuroimaging in a large sample of healthy human subjects to elucidate neural mechanisms underlying this complex genetic association. Morphometrical analyses showed reduced gray matter volume in short-allele carriers in limbic regions critical for processing of negative emotion, particularly perigenual cingulate and amygdala. Functional analysis of those regions during perceptual processing of fearful stimuli demonstrated tight coupling as a feedback circuit implicated in the extinction of negative affect. Short-allele carriers showed relative uncoupling of this circuit. Furthermore, the magnitude of coupling inversely predicted almost 30% of variation in temperamental anxiety. These genotype-related alterations in anatomy and function of an amygdala-cingulate feedback circuit critical for emotion regulation implicate a developmental, systems-level mechanism underlying normal emotional reactivity and genetic susceptibility for depression.

Amygdala↗

PubMed2005

Prevalence and burden of bipolar disorders in European countries.

A literature search, supplemented by an expert survey and selected reanalyses of existing data from epidemiological studies was performed to determine the prevalence and associated burden of bipolar I and II disorder in EU countries. Only studies using established diagnostic instruments based on DSM-III-R or DSM-IV, or ICD-10 criteria were considered. Fourteen studies from a total of 10 countries were identified. The majority of studies reported 12-month estimates of approximately 1% (range 0.5-1.1%), with little evidence of a gender difference. The cumulative lifetime incidence (two prospective-longitudinal studies) is slightly higher (1.5-2%); and when the wider range of bipolar spectrum disorders is considered estimates increased to approximately 6%. Few studies have reported separate estimates for bipolar I and II disorders. Age of first onset of bipolar disorder is most frequently reported in late adolescence and early adulthood. A high degree of concurrent and sequential comorbidity with other mental disorders and physical illnesses is common. Most studies suggest equally high or even higher levels of impairments and disabilities of bipolar disorders as compared to major depression and schizophrenia. Few data are available on treatment and health care utilization.

Age Factors↗

PubMed2005

Recurrent brief depression revisited.

Recurrent Brief Depressive Disorder (RBD) is a well-defined and prevalent mood disorder with an increased risk of suicidal behavior and significant clinical impairment in the community and general practice. Occurring at least monthly with depressive episodes lasting only a few days defines recurrent Brief Depressive Disorder. The lifetime co-occurrence of both RBD and Major Depressive Disorder (MDD), called Combined Depression (CD), substantially increases the risk for attempted suicide, even more than that known for 'pure' MDD. The diagnostic criteria for RBD found in the ICD-10 and DSM-IV are helpful in research and clinical routine as well as several methodological issues, which make clinical diagnostic and drug response evaluation of RBD very different from MDD. Formal differences in the course of RBD and MDD require different designs for drug treatment studies. Denials of disorder, specific methodological requirements, and highly selected patient samples have probably been responsible for false negative results in double blind, placebo-controlled treatment studies. Although several authors reported successful treatment of RBD with different compounds in about 60 patients, it is still not possible to deduce a treatment algorithm for RBD to date. Obviously future treatment studies without the limitations of previous studies are clearly required for RBD. Results of ongoing studies will soon provide the first data on the biological underpinnings of RBD.

Depression↗

PubMed2004

The brain-derived neurotrophic factor val66met polymorphism and variation in human cortical morphology.

A variation in the BDNF gene (val66met) affects the function of BDNF in neurons, predicts variation in human memory, and is associated with several neurological and psychiatric disorders. Here, we show that, in magnetic resonance imaging scans of a large sample of normal individuals, this polymorphism affects the anatomy of the hippocampus and prefrontal cortex, identifying a genetic mechanism of variation in brain morphology related to learning and memory.

Adolescent↗

PubMed2003

Recurrent brief depression--past and future.

Recurrent brief depressive disorder (RBD) is a well-defined and significantly prevalent affective disorder with an increased risk of suicidal behavior and significant clinical impairment in the community and general practice. RBD is characterized by depressive episodes occurring at least once a month and lasting for only a few days. The lifetime co-occurrence of both RBD and major depressive disorder (MDD), called combined depression (CD), increases substantially the risk for suicide attempts, even more than is known for "pure" MDD. Diagnostic criteria for RBD can be found in the ICD-10 and DSM-IV and are helpful in both, research and clinical routine. Furthermore, several methodological issues are covered in this paper, which make clinical diagnostic and drug response evaluation of RBD very different from MDD. However, clinical procedures rather bear a resemblance to those used in the treatment of migraine or epilepsy. Formal differences in the course of RBD and MDD create different needs concerning the design of drug treatment studies. Absence of special methodological requirements and highly selected patient samples has probably been responsible for false negative results in double-blind, placebo-controlled treatment studies. Although several authors reported successful treatment of RBD with different compounds in about 60 patients, it is still not possible to deduce a treatment algorithm for RBD to date. Obviously, future treatment studies without the limitations of previous studies are clearly required for RBD.

Adolescent↗

PubMed2003

Natural course and burden of bipolar disorders.

Despite an abundance of older and more recent retrospective and considerably fewer prospective-longitudinal studies in bipolar disorders I and II, there are still remarkable deficits with regard to our knowledge about the natural course and burden. The considerable general and diagnosis-specific challenges posed by the nature of bipolar disorders are specified, highlighting in particular problems in diagnostic and symptom assessment, shifts in diagnostic conventions and the broadening of the diagnostic concept by including bipolar spectrum disorders. As a consequence it still remains difficult to agree on several core features of bipolar disorders, such as when they begin, how many remit spontaneously and how many take a chronic course. On the basis of clinical and epidemiological findings this paper summarizes (i) a significant need to extend the study of the natural course of bipolar disorder in clinical samples beyond the snapshot of acute episodes to the study of the mid-term and long-term symptom course, associated comorbidities and the associated burden of the disease. (ii) In terms of epidemiological studies, that are also of key importance for resolving the critical issues of threshold definitions in the context of the bipolar spectrum concept, there is a clear need for identifying the most relevant risk factors for the first onset and those for the further illness progression in early stages. Since there are some indications that these critical processes might start as early as adolescence, such studies might concentrate on young cohorts and clearly before these prospective patients come to clinical attention. (iii) The value of both types of studies might be enhanced, if beyond the use of standardized diagnostic interview, special attempts are made to use prospective life- and episode-charting methods for bipolar illnesses.

Age of Onset↗

PubMed2003

Relationship between power spectra of the awake EEG and psychomotor activity patterns measured by short-term actigraphy.

Actigraphy is a quantitative method for the measurement of motor activity. In the present study, actigraphy was used to examine psychomotor correlates of brain activity. Thirty-four psychiatric patients (17 males and 17 females) with different diagnoses participated in this investigation. Directly after EEG recording, motor activity was measured with a wrist actimeter for 15 min in patients in the sitting position. The EEG was quantified by spectrum analysis, and the power spectra as well as other EEG-derived variables were correlated with actigraphic parameters. Occipital and temporoparietal beta1 power was statistically significantly higher in patients with higher activity scores and lower in those with a high density of sleep (SB) or wake bouts (WB). A high density of SB or WB was also positively correlated with higher mean alpha power. Immobile phases measured by actigraphy were positively associated with occipital alpha and with frontal/frontopolar delta activity, preferentially on the side of the left hemisphere. Our results, while preliminary, suggest that short-term actigraphy may be apt to reflect central nervous system arousal.

Benzodiazepines↗

PubMed2002

Opioid addiction changes cerebral blood flow symmetry.

Changes in regional cerebral blood flow (rCBF) due to long-term abuse of opioids such as heroin or morphine are not yet fully understood in humans. The goal of the present study was to investigate rCBF alterations in a large sample of long-term opioid addicts in comparison to healthy controls. We investigated 21 opioid-dependent subjects, who were currently abusing heroin or were enrolled in a methadone or morphine maintenance program, and 36 healthy controls with (99m)Tc-HMPAO single photon emission computed tomography. We found a decrease in rCBF in most regions of interest in patients in comparison to controls. Long-term opioid dependence seems to decrease prefrontal CBF in particular. A right-greater-than-left CBF asymmetry in healthy subjects was reversed in patients. This change in CBF symmetry could reflect the different emotional status of opioid-dependent patients. Our findings are in line with neuropsychological investigations indicating a correlation of mood states with lateralization of hemispheric activation patterns.

Adult↗

PubMed2002

Receptor and transporter imaging studies in schizophrenia, depression, bulimia and Tourette's disorder--implications for psychopharmacology.

Considerable progress has been achieved over the past 15 years in uncovering the biological basis of major psychiatric disorders. To determine patterns of brain dysfunction and to uncover the mechanism of action of centrally active compounds we used single photon emission computerized tomography (SPECT) as well as positron emission tomography (PET) in patients diagnosed with schizophrenia, depression, bulimia and Tourette's disorder. Striatal D2 and 5-HT1A receptors were studied in schizophrenia and 5-HT transporters (5-HTT) in depression and bulimia. Patients were either drug-naïve or drug free, or we studied the influence of specifically acting compounds on receptor/transporter occupancy. We could demonstrate that atypical antipsychotics have a dose-dependent (with the exception of clozapine and quetiapine) lower striatal D2 receptor occupancy rate compared with typical neuroleptics, paralleling the more favourable extrapyramidal side effects of atypical antipsychotics. However, no association between striatal D2 receptor occupancy rates and antipsychotic efficacy has been found. The measurement of 5-HT1A receptors in drug-naïve schizophrenic patients using the in vivo PET methodology revealed an increase of cortical 5-HT1A receptor binding potential in schizophrenia. beta-CIT as a ligand for measurement of 5-HT transporter densities (5-HTT) revealed lower rates in depression compared to age- and sex-matching healthy controls, a measurement that has also been obtained for bulimia. We also documented seasonal variations in brain serotonergic function by our finding of reduced brain 5-HTT availability in winter (compared to summer) in healthy controls. Furthermore, displaceable [123I] beta-CIT binding in the area corresponding to the left striatum (representing predominantly the density of dopamine transporters) was significantly reduced in SAD patients compared to healthy controls. In depression as well as in bulimia, selective serotonin reuptake inhibitors significantly decreased the beta-CIT binding potential, however, no significant dose relationship has been obtained in depression. Genotyping depressed patients for the serotonin transporter promoter gene region (5-HTTLPR) did not provide evidence for in vivo functional regulation of 5-HTT availability by 5-HTTLPR in the thalamus-hypothalamus and mesencephalon-pons of healthy subjects. In patients suffering from Tourette's disorder (TD) we were unable to detect differences of dopamine transporter densities between psychotropic drug-naïve TD patients and controls. Furthermore, no difference could be found between currently treated (with antipsychotics) and psychotropic drug-naïve TD patients. Our data provide insight into the pathophysiology of neuropsychiatric disorders and may guide future psychopharmacological drug developments.

Antidepressive Agents↗

PubMed2002

A longitudinal view of triggers and thresholds of suicidal behavior in depression.

BACKGROUND: Recurrent brief depressive disorder (RBD) and major depressive disorder (MDD) share the same diagnostic picture of full-blown depression and are both associated with increased suicide attempt rates. However, longitudinal diagnostic shifts from RBD to MDD or vice versa, called "combined depression" (CD), have demonstrated a substantially higher risk of suicide attempts in epidemiologic and clinical studies. Following the stress-diathesis model of suicidal behavior, we compared possible triggers and thresholds for suicidal behavior among patients with RBD, MDD, and CD. RBD and MDD diagnoses were based on DSM-IV criteria. Furthermore, the goal of this study was to determine if impulsivity as an underlying factor could explain high suicide attempt rates in CD. METHOD: A structured clinical interview evaluating comorbid Axis I and II disorders and RBD and a battery of instruments assessing suicidal behavior were administered to 101 patients with RBD (N = 27), MDD (N = 33), or CD (N = 41). RESULTS: Patients with CD showed significantly higher (p < .05) scores on measures of suicidal behavior in comparison with RBD and MDD patients. Together with comorbid substance abuse and marital status, CD was among the highest-ranking risk factors for suicide attempts. Impulsivity was identified as a major underlying factor, predicting 80.7% of suicide attempts. CONCLUSION: CD seems to be an important clinical risk factor for the prediction of suicide attempts, similar to risk factors such as substance use disorders and borderline personality disorder. All of these factors share the same diathesis for increased impulsivity and suicidal ideation, which could explain comorbidity and suicidal behavior. The coexistence of a greater propensity for suicidal ideation and impulsivity in RBD might also explain why such patients are more prone to attempt suicide, even if they do not, in the case of RBD, meet the duration criteria for MDD.

Adult↗