Children of parents with major mood and psychotic disorders are at increased risk of psychopathology, including psychotic symptoms. It has been suggested that the risk of psychosis may be more often transmitted from parent to opposite-sex offspring (e.g., from father to daughter) than to same-sex offspring (e.g., from father to son). To test whether sex-specific transmission extends to early manifestations of psychosis, we examined sex-specific contributions to psychotic symptoms among offspring of mothers and fathers with depression, bipolar disorder and schizophrenia. We assessed psychotic symptoms in 309 offspring (160 daughters and 149 sons) aged 8–24 years (mean=13.1, s.d.=4.3), of whom 113 had a mother with schizophrenia, bipolar disorder or major depression and 43 had a father with schizophrenia, bipolar disorder or major depression. In semi-structured interviews, 130 (42%) offspring had definite psychotic symptoms established and confirmed by psychiatrists on one or more assessments. We tested the effects of mental illness in parents on same-sex and opposite-sex offspring psychotic symptoms in mixed-effect logistic regression models. Psychotic symptoms were more prevalent among daughters of affected fathers and sons of affected mothers than among offspring of the same sex as their affected parent. Mental illness in the opposite-sex parent increased the odds of psychotic symptoms (odds ratio (OR)=2.65, 95% confidence interval (CI) 1.43–4.91, P=0.002), but mental illness in the same-sex parent did not have a significant effect on psychotic symptoms in offspring (OR=1.13, 95% CI 0.61–2.07, P=0.697). The opposite-sex-specific parent-of-origin effects may suggest X chromosome-linked genetic transmission or inherited chromosomal modifications in the etiology of psychotic symptoms.

In this selective review of recent research on internalizing disorders in childhood, we focus on four areas: the predictive validity of the diagnoses of depressive and anxiety disorders, rates of comorbidity, the chronology of onsets of the disorders of interest, and transmission of depressive and anxiety disorders in the pedigrees of affected individuals. To synthesize and reconcile findings in these four areas, we approach the information from a developmental perspective and assume that genetically driven biologic processes play a salient role in the expression of depressive and anxiety disorders in childhood. We also comment on the relevance of findings on children and adolescents to the field of depressive and anxiety disorders in adults and make recommendations for further research.

While some investigators believe that the concept of depression is a continuum with mild and severe forms reflecting essentially the same entity, most suspect that the concept is instead heterogeneous and consists of a group of discrete subtypes. If this is so, identifying subtypes is a major priority. Ultimately such subtypes must be understood in terms of their underlying neural and even molecular mechanisms. Yet in order to search for such mechanisms, we still must begin with clinical phenomenology.

Two major subtypes of serious depressions have been proposed. Endogenous or melancholic depression is one, while bipolar depression is another. Thinking about both these subtypes tends to assume an underlying biogenic mechanism that is relatively autonomous, although not necessarily free of environmental influences.

This paper examines a series of attempts to identify discrete subtypes of depression. One approach, used in a series of investigations, involves the use of mathematical techniques such as cluster analysis in order to identify phenomenologically similar subgroups within the depressive spectrum. This approach has consistently identified a melancholic or endogenous syndrome. Our attempts to validate the concept of endogenous depression through examining external correlates, such as family history, have been less successful.

An alternate method for subtyping depression stresses that the bipolar subtype represents a discrete form of severe endogenously caused depression. We bave examined the phenomenology of bipolar versus unipolar depression and found it to differ significantly in a number of respects. Thus, endogenous depression and bipolar depression may represent different phenontena.

Tandis que certains chercheurs définissent la dépression comme continuum composé d’états bénins et graves reflétant essentiellement la même identité, d’autres pensent que le concept de dépression est, en revanche, hétérogène et constitué d’un groupe de sous-catégories distinctes.

Si tel est le cas, identifier ces sous-catégories devient une priorité majeure. De telles sous-catégories doivent être comprises par rapport à leurs mécanismes fondamentaux neuronaux, voire même moléculaires. Toutefois, afin d’effectuer des recherches à ce sujet, il faut toujours commencer par la phénoménologie clinique.

Dans les dépressions graves, deux sous-catégories majeures ont été proposées; l’une est la dépression endogène ou mélancolique et l’autre la dépression bipolaire. On a tendance à postuler l’existence d’un mécanisme biogénique fondamental relativement autonome, bien que pas forcément libre d’influences environnementales.

Cet article étudie une série de tentatives visant à l’identification des sous-catégories distinctes de dépression. Une approche, utilisée dans une série de travaux, consiste à utiliser des techniques mathématiques telles que l’analyse par grappes, afin d’identifier de façon phénoménologique des sous-catégories similaires dans le spectre de la dépression.

Cette approche a identifié d’une façon conséquente un syndrome mélancolique ou endogène. Nos efforts pour valider ce concept de dépression endogène, par exemple la recherche d’antécédents familiaux, ont eu moins de succès.

Une autre méthode pour sous-catégoriser la dépression souligne que la sous-catégorie bipolaire représente une lorme distincte d’une dépression grave provoquée d’une façon endogène. Nous avons examiné la phénoménologie de la dépression bipolaire versus la dépression unipolaire et nous avons trouvé qu’il y a un certain nombre de caractéristiques qui différencient significativement la première de la dernière. Il est donc fort possible que la dépression endogène et la dépression bipolaire soient deux phénomènes distincts.