Familial aggregation of delusional depression: re-examination in a recent family study

Clinical and molecular genetics of psychotic depression

This review provides a comprehensive overview of clinical and molecular genetic as well as pharmacogenetic studies regarding the clinical phenotype of "psychotic depression." Results are discussed with regard to the long-standing debate on categorical vs dimensional disease models of affective and psychotic disorders on a continuum from unipolar depression over bipolar disorder and schizoaffective disorder to schizophrenia. Clinical genetic studies suggest a familial aggregation and a considerable heritability (39%) of psychotic depression partly shared with schizoaffective disorder, schizophrenia, and affective disorders. Molecular genetic studies point to potential risk loci of psychotic depression shared with schizoaffective disorder (1q42, 22q11, 19p13), depression, bipolar disorder, and schizophrenia (6p, 8p22, 10p13-12, 10p14, 13q13-14, 13q32, 18p, 22q11-13) and several vulnerability genes possibly contributing to an increased risk of psychotic symptoms in depression (eg, BDNF, DBH, DTNBP1, DRD2, DRD4, GSK-3beta, MAO-A). Pharmacogenetic studies implicate 5-HTT, TPH1, and DTNBP1 gene variation in the mediation of antidepressant treatment response in psychotic depression. Genetic factors are suggested to contribute to the disease risk of psychotic depression in partial overlap with disorders along the affective-psychotic spectrum. Thus, genetic research focusing on psychotic depression might inspire a more dimensional, neurobiologically and symptom-oriented taxonomy of affective and psychotic disorders challenging the dichotomous Kraepelinian view. Additionally, pharmacogenetic studies might aid in the development of a more personalized treatment of psychotic depression with an individually tailored antidepressive/antipsychotic pharmacotherapy according to genotype.

An overview of the genetics of psychotic mood disorders

This article presents a conceptual review of the genetic underpinnings of psychotic mood disorders. Both unipolar and bipolar forms of mood disorder sometimes feature psychotic symptoms. Some evidence from epidemiological research suggests that psychotic forms of mood disorder specifically might be heritable. Linkage studies of mood disorders in general have also provided some support for that notion, as have associated studies involving serotonin and dopamine genes and psychotic mood disorder. Some research suggests there might be a genetic connection between schizophrenia and bipolar disorder, undermining the Kraepelinian dichotomous classification of the psychoses. Future research should continue to examine psychotic forms of mood disorder using both epidemiological and molecular approaches.

Familial aggregation of psychotic symptoms in a replication set of 69 bipolar disorder pedigrees

We found evidence previously of familial aggregation of psychotic symptoms in 65 bipolar disorder pedigrees. This finding, together with prior evidence from clinical, family, neurobiological, and linkage studies, suggested that psychotic bipolar disorder may delineate a valid subtype. We sought to replicate this finding in 69 new bipolar disorder pedigrees. The presence of psychotic symptoms, defined as hallucinations or delusions, during an affective episode was compared in families of 46 psychotic and 23 non-psychotic bipolar I probands ascertained at Johns Hopkins for the NIMH Bipolar Disorder Genetics Initiative. There were 198 first-degree relatives with major affective disorder including 90 with bipolar I disorder. Significantly more psychotic proband families than non-psychotic proband families (76% vs. 48%) contained at least one affected relative with psychotic symptoms. Psychotic symptoms occurred in 35% of relatives of psychotic probands and in 22% of relatives of non-psychotic probands (P = 0.10). Both psychotic affective disorder generally and psychotic bipolar I disorder clustered significantly in families. These results are consistent with our prior report although the magnitude of the predictive effect of a psychotic proband is less in the replication families. Our findings provide modest support for the validity of psychotic bipolar disorder as a subtype of bipolar disorder. This clinically defined subtype may prove more homogeneous than the disorder as a whole at the level of genetic etiology and of neuropathology/pathophysiology. Families with this subtype should be used to search for susceptibility genes common to bipolar disorder and schizophrenia, and for biological markers that may be shared with schizophrenia.

Pediatric bipolar mood disorder

The diagnosis of bipolar mood disorder (BP) in preadolescents (pediatric mania) has generated considerable controversy in terms of its estimated prevalence and validity as a diagnostic category. The relative paucity of systematic studies and the current diagnostic confusion related to the disorder are often attributed to the apparent discontinuities in the childhood versus adult presentation of the illness, namely, irritability as the predominant "mood" of mania and a continuous course of symptoms. The goal of this article is to review the current literature and identify sources of confusion relating to pediatric mania by considering results to date within a larger context that include findings from studies on (1) BP illness in adults, (2) mood disorders across the lifespan, (3) the role of development in symptom expression, and (4) patterns of heritability in psychiatric disorders. Whereas much remains to be investigated in the validation of the diagnosis for children, integrating results across studies may provide a framework for understanding the differences in the presentation of severe mood disorders in children and adults.