Low dopamine-beta-hydroxylase: a biological sequela of abuse and neglect?

The impact of childhood trauma and daily life experiences on emotional and psychotic symptom intensity in psychosis: An experience sampling study

Adverse childhood experiences create vulnerability to psychosis through biological and cognitive changes, and that may be observed as an increased emotional and psychotic response to daily life experiences in adulthood. This study aims to examine the effects of childhood maltreatment on psychotic patients' daily stress and emotional and psychotic intensity related to various experiences throughout the day. Daily activities and events, and emotional and psychotic intensity of forty-one psychotic patients were assessed with the Experience Sampling Method. The Childhood Trauma Questionnaire (CTQ) was used to evaluate childhood adversities. Multilevel regression analyses showed that all trauma subtypes, except for sexual abuse, were associated with increased psychosis and event-stress. Emotional maltreatment was the most associated trauma type with high negative and low positive affect and increased daily stress. Patients reported the highest stress and negative affect related to internal experiences but the lowest stress related to recreational actions. Social activities were also associated with higher positive affect and lower stress and psychosis, with the high CTQ group having greater stress in those activities. Our study demonstrates the negative impact of childhood trauma, especially emotional maltreatment, on daily stress and emotional and psychotic intensity in psychotic patients via different daily experiences.

Biological correlates of personality: considerations on the possible usefulness of central nervous system peripheral markers

Although a great deal of biological research has been carried out on several psychiatric disorders, it is disappointing to see how little progress has been made in the field of the biology of personality. The authors underline the methodological problems that arise in the investigation of biological substrates of human personality and review both currently available and putative peripheral markers of the central nervous system that might be used in further human studies.

Dopamine receptor D2 (DRD2), dopamine transporter solute carrier family C6, member 4 (SLC6A3), and catechol-O-methyltransferase (COMT) genes as moderators of the relation between maternal history of maltreatment and infant emotion regulation

Although infants less than 18 months old are capable of engaging in self-regulatory behavior (e.g., avoidance, withdrawal, and orienting to other aspects of their environment), the use of self-regulatory strategies at this age (as opposed to relying on caregivers) is associated with elevated behavioral and physiological distress. This study investigated infant dopamine-related genotypes (dopamine receptor D2 [DRD2], dopamine transporter solute carrier family C6, member 4 [SLC6A3], and catechol-O-methyltransferase [COMT]) as they interact with maternal self-reported history of maltreatment to predict observed infant independent emotion regulation behavior. A community sample (N = 193) of mother–infant dyads participated in a toy frustration challenge at infant age 15 months, and infant emotion regulation behavior was coded. Buccal cells were collected for genotyping. Maternal maltreatment history significantly interacted with infant SLC6A3 and COMT genotypes, such that infants with more 10-repeat and valine alleles of SLC6A3 and COMT, respectively, relative to infants with fewer or no 10-repeat and valine alleles, utilized more independent (i.e., maladaptive) regulatory behavior if mother reported a more extensive maltreatment history, as opposed to less. The findings indicate that child genetic factors moderate the intergenerational impact of maternal maltreatment history. The results are discussed in terms of potential mechanism of Gene × Environment interaction.

Pharmacogenetic randomized trial for cocaine abuse: disulfiram and dopamine β-hydroxylase

BACKGROUND

Disulfiram has been an effective cocaine addiction pharmacotherapy, and one of its possible mechanisms of efficacy is through copper chelation and inhibition of an enzyme involved in catecholamine metabolism, dopamine β-hydroxylase (DβH), which converts dopamine to norepinephrine. A variant in the gene encoding DβH leads to reduced DβH activity, and as such, disulfiram might not be an effective treatment of cocaine dependence for individuals with this variant. This study explored that potential matching.

METHODS

Seventy-four cocaine- and opioid-codependent (DSM-V) subjects were stabilized on methadone for 2 weeks and subsequently randomized into disulfiram (250 mg/day, n = 34) and placebo groups (n = 40) for 10 weeks. We genotyped the DBH gene polymorphism, -1021C/T (rs1611115), that reduces DβH enzyme levels and evaluated its role for increasing cocaine free urines with disulfiram.

RESULTS

With repeated measures analysis of variance, corrected for population structure, disulfiram pharmacotherapy reduced cocaine-positive urines from 80% to 62% (p = .0001), and this disulfiram efficacy differed by DBH genotype group. Patients with the normal DβH level genotype dropped from 84% to 56% on disulfiram (p = .0001), whereas those with the low DBH level genotype showed no disulfiram effect.

CONCLUSIONS

This study indicates that the DBH genotype of a patient could be used to identify a subset of individuals for which disulfiram treatment might be an effective pharmacotherapy for cocaine dependence.

Neurobiological adaptations to violence across development

Developmental adaptations to violent environments involve a multitude of cascading effects spanning many levels of analysis from genes to behavior. In this review, we (a) examine the potentiating effects of violence on genetic vulnerabilities and the functioning of neurotransmitter systems in producing both internalizing and externalizing psychopathology; (b) describe implications of violence exposure for brain development, particularly within the hippocampus and prefrontal cortex; and (c) consider the effects of violence on developing human stress and startle responses. This review integrates literatures on the developmental effects of violence among rodents, nonhuman primates, and humans. Many neurobiological changes that are adaptive for survival in violent contexts become maladaptive in other environments, conferring life-long risk for psychopathology.

Pharmacogenetic treatments for drug addiction: cocaine, amphetamine and methamphetamine

BACKGROUND

Pharmacogenetics uses genetic variation to predict individual differences in response to medications and holds much promise to improve treatment of addictive disorders.

OBJECTIVES

To review how genetic variation affects responses to cocaine, amphetamine, and methamphetamine and how this information may guide pharmacotherapy.

METHODS

We performed a cross-referenced literature search on pharmacogenetics, cocaine, amphetamine, and methamphetamine.

RESULTS

We describe functional genetic variants for enzymes dopamine-beta-hydroxylase (DbetaH), catechol-O-methyltransferase (COMT), and dopamine transporter (DAT1), dopamine D4 receptor, and brain-derived neurotrophic factor (BDNF). A single nucleotide polymorphism (SNP; C-1021T) in the DbetaH gene is relevant to paranoia associated with disulfiram pharmacotherapy for cocaine addiction. Individuals with variable number tandem repeats (VNTR) of the SLC6A3 gene 3'-untranslated region polymorphism of DAT1 have altered responses to drugs. The 10/10 repeat respond poorly to methylphenidate pharmacotherapy and the 9/9 DAT1 variant show blunted euphoria and physiological response to amphetamine. COMT, D4 receptor, and BDNF polymorphisms are linked to methamphetamine abuse and psychosis.

CONCLUSIONS

Disulfiram and methylphenidate pharmacotherapies for cocaine addiction are optimized by considering polymorphisms affecting DbetaH and DAT1 respectively. Altered subjective effects for amphetamine in DAT1 VNTR variants suggest a 'protected' phenotype.

SCIENTIFIC SIGNIFICANCE

Pharmacogenetic-based treatments for psychostimulant addiction are critical for successful treatment.

Development and neurotransmitter-environmental interactions

Norepinephrine (NE), dopamine (DA), and serotonin (5HT) are three of the more than thirty neurotransmitters (NTs) in the brain. Axons from a relatively small number of cell bodies located in the midbrain and brainstem branch out to connect with virtually all areas of the brain. Via these connections, these three NTs participate in the regulation of several behavioral systems that help modulate the interaction of the individual with his/her environment. Because the NT systems continue to develop after birth, interactions between the individual and his/her environment after birth may affect the development of these systems and have long-term effects on the individual's behavior. Animal studies indicate that early experience affects behavior and biogenic amine systems in the adult. For instance, one study showed that maternal deprivation, which is analogous to human neglect, affects the NE system in monkeys and may have a long-lasting effect on its development and function. In a previous study, similar relationships between early neglect and the NE system in humans were examined. Our results show that emotionally disturbed children with a history of neglect have lower dopamine-β-hydroxylase (DβH) activity, an enzyme involved in the synthesis of NE, than do children with no history of neglect. Additionally, the children with a history of neglect have lower systolic and diastolic blood pressure, both of which are functions mediated by the NE system, than the other children studied. These results support findings in animal studies that neglect affects the development of the NE system in a long-lasting, if not permanent way.

A functional dopamine-beta-hydroxylase gene promoter polymorphism is associated with impulsive personality styles, but not with affective disorders

Dopamine-beta-hydroxylase (DbetaH) catalyzes the conversion of dopamine to norepinephrine in central noradrenergic and adrenergic neurons and thus is critically involved in the biosynthesis of catecholamines. There are equivocal findings concerning the question whether or not DssH activity levels are altered in affective disorders or in subtypes of affective disorders. Moreover, information about the role of dopamine beta-hydroxylase (DBH) genotype, which explains a large part of the variance of enzymatic activity, in affective disorders and personality dimensions is limited. To resolve these inconsistencies, association tests were performed using four independent samples, healthy volunteers (N = 387), patients with affective disorders (N = 182), adult attention deficit hyperactivity disorder (ADHD) patients (N = 407), and patients with personality disorders (N = 637). In the latter two samples, the revised NEO personality inventory (NEO-PI-R) was administered. All participants were genotyped for a putatively functional single nucleotide polymorphism (C-1021T, rs1611115). No differences in DBH C-1021T genotype distribution were observed between patients with affective disorders and healthy control subjects. Also when the patient sample was divided into uni- and bipolar patients versus controls, no significant differences emerged. Furthermore, no clear-cut association was detected between the TT genotype and personality disorder clusters while there was a significant association with adult ADHD. However, personality disorder patients carrying the DBH TT genotype exhibited higher neuroticism and novelty seeking scores as compared to individuals with the CC or CT genotype. Analyses on the level of the neuroticism and novelty seeking subscales revealed that the DBH TT genotype was primarily associated with personality features related to impulsiveness and aggressive hostility. Also adult ADHD patients carrying the homozygous TT genotypes displayed by significantly increased neuroticism scores; when both personality disorder and adult ADHD patient were analyzed together, TT carriers also displayed by significantly lower conscientiousness levels. Our results thus do not implicate the DBH C-1021T polymorphism in the pathophysiology of depressive disorders or personality disorders, yet homozygosity at this locus appears to increase the risk towards personality traits related to impulsiveness, aggression and related disease states, namely adult ADHD. These data argue for a dimensional rather than categorical effect of genetic variance in DBH activity; accordingly, the inconsistency of previous findings concerning DbetaH levels in affective disorders might be caused by the underlying association of the TT genotype at DBH-1021 with impulsive personality traits.

Sensation seeking and risk-taking propensity as mediators in the relationship between childhood abuse and HIV-related risk behavior

OBJECTIVES

Although a wealth of literature suggests that childhood physical, emotional, and sexual abuse are related to later-life HIV-related risk behaviors, few studies have explored disinhibition (e.g., impulsivity, risk-taking propensity, and sensation-seeking) as a risk factor in this relationship.

METHOD

This cross-sectional study examined impulsivity, risk-taking propensity, and sensation seeking as mediators in the relationship between abuse history and engagement in HIV-related risk behaviors among a sample of 96 inner-city African American adolescents.

RESULTS

Findings indicated that abuse history was positively related to self-reported engagement in HIV-related risk behaviors (B=.027, SE .008, beta=.32, sr(2)=.105, p=.001), as well as risk-taking propensity (B=.35, SE .11, beta=.30, sr(2)=.090, p=.003) and sensation seeking (B=.17, SE .05, beta=.35, sr(2)=.124, p=.0004). Abuse history was not related to impulsivity. Further, while sensation-seeking and risk-taking propensity (to a lesser extent) mediated this relationship, impulsivity did not.

CONCLUSIONS

These findings provide an initial step in the examination of the mechanisms underlying the relationship between childhood abuse and engagement in HIV-related risk behaviors.

Polymorphisms in the DBH and DRD2 gene regions and smoking behavior

The DRD2 TaqI A and DBH-1021 C/T polymorphisms were genotyped in smoking alcoholics (N = 100), non-alcoholic smokers (N = 120) and nonsmoking controls (N = 112). Alcoholic and non-alcoholic smokers presented a higher frequency of the DRD2 TaqI A1 allele (P = 0.04) than non-smoking controls. Individuals who had at least one DBH-1021 T allele smoked fewer cigarettes per day than CC homozygotes (P = 0.03). These results are coherent with the expected effects of these polymorphisms on dopaminergic function.

Linking posttraumatic stress disorder and psychosis: a look at epidemiology, phenomenology, and treatment

Several recent studies have provided direct evidence for the link between posttraumatic stress disorder (PTSD) and psychosis. Patients with psychotic disorders are known to be at a higher risk of traumatization and PTSD. Additionally, preclinical and clinical data suggest that the effects of trauma exposure on neural networks may provide a common diathesis for disorders like PTSD and schizophrenia. This article reviews evidence on a) the magnitude of association between PTSD and psychosis, b) the causal mechanisms implicated, and c) treatment considerations relevant to this association. A comprehensive MEDLINE search was conducted, and articles pertinent to epidemiological, clinical, and treatment aspects of comorbid PTSD and psychosis were identified. High rates of PTSD characterize patients with severe mental illness. Psychotic phenomena may also be a relatively common manifestation in patients with chronic PTSD. However, in clinical settings, the diagnosis is often missed, and few systematic guidelines exist for the identification and treatment of these comorbidities. Future neurobiological and treatment studies may be useful in better informing the clinical management of these subgroups.

The contribution of early traumatic events to schizophrenia in some patients: a traumagenic neurodevelopmental model

The current diathesis-stress model of schizophrenia proposes that a genetic deficit creates a predisposing vulnerability in the form of oversenstivity to stress. This model positions all psychosocial events on the stress side of the diathesis-stress equation. As an example of hypotheses that emerge when consideration is given to repositioning adverse life events as potential contributors to the diathesis, this article examines one possible explanation for the high prevalence of child abuse found in adults diagnosed schizophrenic. A traumagenic neurodevelopmental (TN) model of schizophrenia is presented, documenting the similarities between the effects of traumatic events on the developing brain and the biological abnormalities found in persons diagnosed with schizophrenia, including overreactivity of the hypothalamic-pituitary-adrenal (HPA) axis; dopamine, norepinephrine, and serotonin abnormalities; and structural changes to the brain such as hippocampal damage, cerebral atrophy, ventricular enlargement, and reversed cerebral asymmetry. The TN model offers potential explanations for other findings in schizophrenia research beyond oversensitivity to stress, including cognitive impairment, pathways to positive and negative symptoms, and the relationship between psychotic and dissociative symptomatology. It is recommended that clinicians and researchers explore the presence of early adverse life events in adults with psychotic symptoms in order to ensure comprehensive formulations and appropriate treatment plans, and to further investigate the hypotheses generated by the TN model.

Plasma dopamine beta-hydroxylase activity in psychotic and non-psychotic post-traumatic stress disorder

Recognition and treatment of comorbid chronic psychotic symptoms in post-traumatic stress disorder (PTSD) has become of increasing clinical interest. Altered dopamine beta-hydroxylase (DBH) activity has been reported in mood disorders. Plasma DBH is reduced in major depression with psychosis and elevated in bipolar disorder with psychosis compared with their respective non-psychotic diagnostic groups. DBH is likely a trait marker with interindividual variations secondary to genetic polymorphism. We therefore evaluated DBH activity in PTSD patients with and without psychotic features and compared these groups with age- and gender-matched control subjects. Vietnam combat veterans with PTSD (n = 19) (including patients with and without psychotic features) and normal control subjects (n = 22) had plasma DBH enzyme activity assayed photometrically. DBH was significantly higher in patients with PTSD with psychotic features than in patients without psychotic features (80.6 +/- 13.4 vs. 42.1 +/- 7.3 mM/min, P < 0.01) and was also higher than normal control subjects (46.12 +/- 4.93, P < 0.01). Plasma DBH activity may differentiate psychotic and non-psychotic subtypes of PTSD. The observed changes are, interestingly, opposite to those seen in psychotic depression but comparable to psychotic bipolar disorder. Since DBH is a genetic marker, this may reflect individual vulnerabilities to develop psychosis in the context of trauma.

The serotonin hypothesis of aggression revisited

Many contemporary theorists believe serotonin (5-HT) neurotransmitter functioning plays a role in the regulation of human aggressive behavior. We argue that the evidence supporting this 5-HT hypothesis of human aggression is less compelling than commonly assumed, due to (a) conflicting study results, and (b) significant methodological limitations of existing studies. Recent models that integrate the role of psychological and contextual variables in 5-HT--associated aggression are reviewed. The need to incorporate psychometrically sound measures of aggression in 5-HT studies, to use experimental and longitudinal designs, and to test hypotheses drawn from multifactorial models in future research is advocated.

Maltreatment, conscience functioning and dopamine beta hydroxylase in emotionally disturbed boys

OBJECTIVE

Identify associations among early maltreatment, sufficiencies, and psychopathological interferences in the domains of conscience functioning and low serum dopamine beta hydroxylase activity.

METHOD

Nineteen emotionally disturbed boys screened for maltreatment experiences were compared according to age at onset of maltreatment, enzyme activity, and their conscience functioning in the domain of moral valuation. They were also compared in conscience functions to 19 age and sex matched normal counterparts.

RESULTS

Subjects who endured maltreatment prior to 36 months had developmental delays and interferences with functioning in more conscience domains than those who were either spared such experiences or who endured maltreatment later in life. Subjects with low enzyme activity had significantly more interference with authority and peer valuation than subjects with high enzyme activity. Greater interference with valuation was associated with lower enzyme activity and more frequent abuse prior to 36 months.

CONCLUSIONS

Psychosocial sequelae of early maltreatment have been identified in the domains of conscience. An association has been established between pathological interference in the domain of moral valuation and a putative neurobiologic sequelae of early maltreatment. Implications for future research in the psychobiology of maltreatment are discussed.

Polygenic inheritance of Tourette syndrome, stuttering, attention deficit hyperactivity, conduct, and oppositional defiant disorder: the additive and subtractive effect of the three dopaminergic genes--DRD2, D beta H, and DAT1

Polymorphisms of three different dopaminergic genes, dopamine D2 receptor (DRD2), dopamine beta-hydroxylase (D beta H), and dopamine transporter (DAT1), were examined in Tourette syndrome (TS) probands, their relatives, and controls. Each gene individually showed a significant correlation with various behavioral variables in these subjects. The additive and substractive effects of the three genes were examined by genotyping all three genes in the same set of subjects. For 9 of 20 TS associated comorbid behaviors there was a significant linear association between the degree of loading for markers of three genes and the mean behavior scores. The behavior variables showing the significant associations were, in order attention deficit hyperactivity disorder (ADHD), stuttering oppositional defiant, tics, conduct, obsessive-compulsive, mania, alcohol abuse and general anxiety-behaviors that constitute the most overt clinical aspects of TS. For 16 of the 20 behavior scores there was a linear progressive decrease in the mean score with progressively lesser loading for the three gene markers. These results suggest that TS, ADHD, stuttering oppositional defiant and conduct disorder, and other behaviors associated with TS, are polygenic, due in part to these three dopaminergic genes, and that the genetics of other polygenic psychiatric disorders may be deciphered using this technique.

Serum dopamine beta hydroxylase and maltreatment in psychiatrically hospitalized boys

Fifty boys, hospitalized on a school-age and an adolescent unit in an intermediate length psychiatric hospital, were studied while off psychoactive medication to determine how serum dopamine beta hydroxylase (DBH) activity varies with different childhood maltreatment experiences. Childhood maltreatment was categorized according to onset (before 36 months old, between 36-72 months old and over 72 months old). Childhood maltreatment groups were compared with a group of psychiatrically hospitalized boys who had neither been abused nor neglected. Boys who were younger than 72 months at age of onset of maltreatment had significantly lower DBH activity than those who had experienced maltreatment later in childhood and those who had not been subjected to abuse or neglect. This difference appeared attributable to the DBH activity of school age (but not adolescent) boys who had been abused/neglected before 72 months. Boys with a principal diagnosis of conduct disorder solitary aggressive type had lower DBH activity than boys without this diagnosis regardless of whether or not they had been maltreated. Low serum DBH may be a biological sequela of maltreatment early in life that correlates with the development of conduct disorder solitary aggressive type in boys.

Alpha-1- and 2-adrenoceptor subsensitivity in siblings of opioid addicts with personality disorders and depression

Noradrenergic receptor sensitivity of 16 healthy male siblings of heroin addicts and of 8 age and sex-matched controls was examined by administering a clonidine stimulation test and by measuring the resulting growth hormone (GH) (alpha-2-adrenoceptors) and beta-endorphin (beta-endorphin) (alpha-1-adrenoceptors) responses. Siblings were divided into two groups: A = siblings of heroin addicts with personality disorders and high aggressivity and B = siblings of heroin addicts without mental disorders. The GH and beta-endorphin responses to clonidine were blunted in group A subjects compared with controls and normal in group B.

Sensation seeking in psychiatrically disturbed youth: relationship to biochemical parameters and behavior problems

OBJECTIVE

Relatively little research has been conducted on the relationship of personality traits or behavioral tendencies with biological parameters in youth. This study was intended to determine whether relationships exist between self-reported sensation-seeking tendencies and biochemical parameters in boys.

METHOD

Twenty-five male youth aged 8 to 15 years admitted to a residential diagnostic center because of noncompliant, disruptive, and/or antisocial behavior were studied. Biochemical parameters associated with sensation seeking in adults or antisocial behavior were measured along with diagnoses, behavior ratings, and self-reported sensation seeking.

RESULTS

High sensation seeking, as assessed on a newly developed sensation-seeking scale for children, was inversely correlated with 3-methoxy-4-hydroxyphenylglycol (MHPG) levels in the older youth (> or = 12.0 years) but not in the younger boys (< 12.0 years) in the group. Elevations on the sensation seeking scale also correlated marginally in these older youth with parent-reported problems on a behavior rating scale, reflecting "delinquent" behavioral tendencies.

CONCLUSIONS

The findings support hypothesized noradrenergic dysregulation in some sensation-seeking persons (including youth > or = 12.0 years) and the relationship between high sensation-seeking tendencies and antisocial or disruptive behavioral disorder.

Dopamine-beta-hydroxylase in behaviorally disturbed youth. Relationship between teacher and parent ratings

A series of neurotransmitters, metabolites, and enzymes considered relevant to emotional and behavioral disorders was studied in blood samples obtained from boys admitted to a residential setting because of disruptive or unmanageable behavior in their home environments. The youth were categorized into mainly prepubertal (under 12.0 years) and pubertal/post pubertal (12.0 years and over) groups. Behavior ratings of the younger group completed by parents revealed significant inverse correlations between several behavioral factors and dopamine-beta-hydroxylase (DBH) activity levels, notably in the aggressive behavior and antisocial domains. Teacher ratings completed after about 1 month of living in the residential setting also showed numerous significant, but positive, correlations between several behavior factors and DBH activity levels. Furthermore, teacher and parent ratings themselves often were significantly and inversely correlated. The findings related to DBH activity levels were strongest in the younger group of boys. The results are discussed in terms of the possibility that low DBH activity in boys reflects a vulnerability towards behavioral disorder, which in certain environments becomes manifested by conduct problems and antisocial behavior.

Biodevelopmental aspects of conduct disorder in boys

The association between biochemical parameters and conduct disorder (CD) was studied in 22 boys admitted to a residential center. Three-methoxy-4-hydroxyphenylglycol (MHPG) levels were significantly higher in prepubertal CD youth than in pubertal/post pubertal CD youth. Homovanillic acid (HVA) levels were significantly lower in CD youth under age 12.0 years than in non CD youth under age 12.0 years. The implications of these biodevelopmental findings in the study of CD are discussed.