István Benák

Association of the GABRD gene and childhood-onset mood disorders

The chromosome 1p36 region was previously indicated as a locus for susceptibility to recurrent major depressive disorder based on a linkage study in a sample of 497 sib pairs. We investigated the gamma‐aminobutyric acid A (GABAA) δ receptor subunit gene, GABRD, as a susceptibility gene to childhood‐onset mood disorders (COMD) because of substantial evidence implicating GABAergic dysfunction in mood disorders and the position of this gene near the 1p36 linkage region. Using a sample consisting of 645 Hungarian families with a child/adolescent proband diagnosed with a mood disorder with the onset of the first episode before age 15, we found some evidence for the association of two polymorphisms located within the gene, rs2376805 and rs2376803, as well as significant evidence for biased transmission of the haplotypes of these two markers (global χ2 test for haplotypes = 12.746, 3 df, P = 0.0052). Furthermore, significant evidence of association was only observed in male subjects (n = 438) when the results were analyzed by sex (χ2 = 9.000 1 df, P = 0.003 for rs2376805). This was in contrast with the previous linkage findings, as LOD scores exceeding 3 were only in female–female pairs in that study. These findings point to the GABRD gene as a susceptibility gene for COMD; however, this gene may not explain the previous linkage finding.

G72/G30 (DAOA) and juvenile-onset mood disorders

The chromosome 13q region has been linked to bipolar disorder in a number of genome scans as well as focused linkage studies. Previously we identified linkage to the 13q32 region in a genome scan of 146 affected sibling pair families from Hungary with juvenile‐onset mood disorders. Within this region are the overlapping genes G72/G30, with G72 now officially named as D‐amino‐acid oxidase activator (DAOA). This locus has been associated with panic disorder, schizophrenia, and bipolar disorder. In this study, we tested for association to 11 markers in these genes and mood disorders in a sample of 646 nuclear families identified with a proband with onset of a mood disorder before 14.9 years of age. We identified evidence for association to three markers within the gene (rs2391191, rs3918341, rs1935062), two of which had been associated with bipolar disorder in previous studies. When corrected for the number of markers tested, the results were no longer significant, however the prior evidence for association of this gene in multiple studies points to this gene as a potential contributor to juvenile‐onset mood disorders.

Genome scan in sibling pairs with juvenile-onset mood disorders: Evidence for linkage to 13q and Xq.

Mood disorders (bipolar and depressive disorders) in children and adolescents are associated with significant morbidity and mortality. Twin and family studies, for the most part, indicate higher familiality and heritability for mood disorders that onset in childhood/adolescence than those that onset in adulthood. To identify the genetic contribution to mood disorders that onset in childhood/adolescence, we performed a genome scan on 146 nuclear families from Hungary containing an affected proband and affected siblings. In total, the pedigrees contained 303 affected children: 146 probands, 137 siblings with a first episode of mood disorder before 14.9 years of age, and 20 siblings with onset of their first episode after 14.9 years of age but before the age of 18. The results of the genome scan using 405 microsatellite markers did not provide evidence for linkage at the recommended genome wide significance level for any novel loci. However, markers on two chromosomes, 13q and Xq, provided evidence for linkage in regions previously identified as linked to bipolar disorder in multiple studies. For the marker on chromosome 13q the peak non‐parametric multipoint LOD score was at the marker D13S779 (LOD = 1.5, P = 0.004). On chromosome Xq, evidence for linkage was observed across a large region spanning two regions previously linked to bipolar disorder; Xq24 to Xq28, with a peak at marker TTTA062 (LOD 2.10, P = 0.0009) in Xq28. Results for these regions exceed the recommended P‐value for a replication study of P < 0.01 and thus provide evidence for these two loci as contributing to mood disorders with juvenile onset.

Parasympathetic nervous system activity predicts mood repair use and its effectiveness among adolescents with and without histories of major depression.

Depressive disorders that onset in the juvenile years have been linked to far-reaching adverse consequences, making it imperative to elucidate key mechanisms and contributory factors. Excessive use of regulatory responses that exacerbate sadness (maladaptive mood repair) or insufficient use of regulatory responses that reduce it (adaptive mood repair) may reflect behavioral mechanisms of depression risk. Cardiac vagal control, indexed by patterns of respiratory sinus arrhythmia (RSA), has received attention as a putative physiological risk factor for depression. Although mood repair and RSA are related, the nature of this relationship is not well characterized in the context of depression risk. Therefore, we tested alternative models of the relationships between RSA patterns (at rest and in response to a sad film), trait mood repair, and the effectiveness of a mood repair response in the laboratory (state mood repair) among adolescents with depression histories (n = 210) and emotionally healthy peers (n = 161). In our data, a mediation model best explained the association between the key constructs: Adolescents with normative RSA patterns exhibited lower levels of depression and trait maladaptive mood repair, and benefited more from instructed (state) mood repair in the laboratory. By contrast, adolescents with atypical RSA patterns exhibited higher levels of depression and dispositional maladaptive mood repair, which, in turn, mediated the relations of RSA patterns and depression symptoms. Atypical RSA patterns also predicted reduced benefits from laboratory mood repair.

Mood repair via attention refocusing or recall of positive autobiographical memories by adolescents with pediatric-onset major depression

BACKGROUND Impaired emotion regulation is increasingly recognized as a core feature of depressive disorders. Indeed, currently and previously depressed adults both report greater problems in attenuating sadness (mood repair) in daily life than healthy controls. In contrast, studies of various strategies to attenuate sad affect have mostly found that currently or previously depressed adults and controls were similarly successful at mood repair in the laboratory. But few studies have examined mood repair among depression-prone youths or the effects of trait characteristics on mood repair outcomes in the laboratory. METHODS Adolescents, whose first episode of major depressive disorder (MDD) had onset at age 9, on average (probands), and were either in remission or depressed, and control peers, watched a sad film clip. Then, they were instructed to engage in refocusing attention (distraction) or recalling happy memories. Using affect ratings provided by the youths, we tested two developmentally informed hypotheses about whether the subject groups would be similarly able to attenuate sadness via the two mood repair strategies. We also explored if self-reported habitual (trait) mood repair influenced laboratory performance. RESULTS Contrary to expectations, attention refocusing and recall of happy memories led to comparable mood benefits across subjects. Control adolescents reported significantly greater reductions in sadness than did depressed (Cohens d = .48) or remitted (Cohens d = .32) probands, regardless of mood repair strategy, while currently depressed probands remained the saddest after mood repair. Habitual mood repair styles moderated the effects of instructed (state) mood repair in the laboratory. CONCLUSIONS Whether depressed or in remission, adolescents with MDD histories are not as efficient at mood repair in the laboratory as controls. But proband-control group differences in mood repair outcomes were modest in scope, suggesting that the abilities that subserve affect regulation have been preserved in probands to some degree. Further information about the nature of mood repair problems among youths with depression histories would help to better understand the clinical course of MDD and to design personalized interventions for depression.

Positive Affectivity Is Dampened in Youths With Histories of Major Depression and Their Never-Depressed Adolescent Siblings

Although hedonic capacity is diminished during clinical depression, it is unclear whether that deficit constitutes a risk factor or persists after depression episodes remit. To examine these issues, adolescents with current/past major depression (probands; n = 218), never-depressed biological siblings of probands (n = 207), and emotionally well controls (n = 183) were exposed to several positively valenced probes. Across baseline and hedonic probe conditions, controls consistently reported higher levels of positive affect than high-risk siblings, and siblings reported higher levels of positive affect than probands (remitted and depressed probands’ reports were similar). Extent of positive affect across the protocol predicted adolescents’ self-reports of social support network and parental reports of offspring’s use of various adaptive mood repair responses in daily life. Attenuated hedonic responding among youths remitted from depression offers partial support for anhedonia as a trait, whereas its presence among never-depressed high-risk siblings argues for anhedonia as a potential diathesis for clinical depression.

Juvenile onset depression alters cardiac autonomic balance in response to psychological and physical challenges

Cardiac autonomic balance (CAB) indexes the ratio of parasympathetic to sympathetic activation (Berntson, Norman, Hawkley, & Cacioppo, 2008), and is believed to reflect overall autonomic flexibility in the face of environmental challenges. However, CAB has not been examined in depression. We examined changes in CAB and other physiological variables in 179 youth with a history of juvenile onset depression (JOD) and 161 healthy controls, in response to two psychological (unsolvable puzzle, sad film) and two physical (handgrip, and forehead cold pressor) challenges. In repeated measures analyses, controls showed expected reductions in CAB for both the handgrip and unsolvable puzzle, reflecting a shift to sympathetic relative to parasympathetic activation. By contrast, JOD youth showed increased CAB from baseline for both tasks (ps<.05). No effects were found for the forehead cold pressor or sad film tasks, suggesting that CAB differences may arise under conditions requiring greater attentional control or sustained effort.

BDNF Val66Met polymorphism and stressful life events in melancholic childhood-onset depression

Introduction Brain-derived neurotrophic factor (BDNF) polymorphisms have been examined for their contribution toward depression with equivocal results. More homogeneous phenotypes might be used to improve our understanding of genetic liability to depression. The aim of our study was to (a) test for an association between the BDNF Val66Met polymorphism and childhood-onset melancholic depression and (b) to examine the interactive effects of stressful life events (SLE) and the Val66Met polymorphism on the risk of childhood-onset melancholic depression. Materials and methods A total of 583 depressed probands were involved in this study (162 of the melancholic subtype). Diagnoses were derived through the Interview Schedule for Children and Adolescents – Diagnostic Version and life event data were collected using an Intake General Information Sheet. Results Overall, 27.8% of the participants fulfilled the criteria for melancholy. In the melancholic group, the proportion of females was higher (53.1%), although there were more males in the overall depressed sample. We detected no significant differences in genotype or allele frequency between the melancholic and the nonmelancholic depressed group. The BDNF Val66Met polymorphism and SLE interaction was not significantly associated with the melancholy outcome. Conclusion In our study, females were more prone to developing the early-onset melancholic phenotype. To our knowledge, this is the first study to investigate the differentiating effect of the genotype and the G×E interaction on the melancholic phenotype in a large sample of depressed young patients. We did not find an association between the melancholic subtype of major depression and the BDNF genotype and SLE interaction in this sample, which is representative of the Hungarian clinic-referred population of depressed youths.

Dysregulated Behavioral Responses to Hedonic Probes Among Youth With Depression Histories and Their High-Risk Siblings

Affect dysregulation in response to rewarding stimuli has been proposed as a vulnerability factor for major depressive disorder (MDD). However, it remains unclear how affective behavioral dynamics may be altered among individuals who are at high risk for depression but not currently depressed. We examined the dynamics of affective facial behavior during hedonic probes among 3 groups of adolescents: remitted probands who had histories of childhood-onset MDD (n = 187), never-depressed siblings of probands (high familial risk; n = 207), and healthy controls (n = 166). Participants’ happy and sad facial expressions were coded during 3 hedonic laboratory tasks: receiving a preferred prize, describing a positive autobiographical memory, and watching a humorous film. Happy and sad behavioral dynamics were indexed by mean level- and time-dependent reactivity, variability (mean of the squared successive differences), and inertia (autocorrelation). Relative to controls, probands and siblings exhibited a more rapid decrease in happy behaviors, and probands exhibited higher inertia of sad behaviors during hedonic probes. Both probands and siblings exhibited lower inertia of sad behaviors while receiving a desired prize, which highlights the importance of context variation in testing hypotheses. Overall, our study provides new evidence that hedonic behavioral dysregulation, as reflected in dynamic facial behavior, may highlight depression vulnerability.