When Depression Becomes Psychotic

% of readers think this story is Fact. Add your two cents.

The number of studies reporting significant and clinically relevant differences between psychotic depression (PD) and non-PD has increased considerably over the past decades. This summary of the current evidence suggests that PD now fulfils the criteria for a valid psychiatric syndrome.

The suggested redefinition of PD in the ICD-11 is merited and such a revision will be of benefit to both research and clinical practice.

In the current issue of Psychotherapy and Psychosomatics, a group of Danish investigators is presenting data that support a new classification of psychotic depression. Depression accompanied by psychotic symptoms is referred to as delusional or psychotic depression (PD). PD is prevalent, underdiagnosed, undertreated and has a high morbidity and mortality, but has received disproportionally little attention compared with other less prevalent and less severe mental disorders.

Based on the detection of a number of biological, clinical, therapeutic and prognostic differences between PD and non-psychotic depression (non-PD), it was proposed that psychotic depression should be categorized as a distinct syndrome in the DSM-IV. This paper deals with the arguments in favour of and against classifying PD as a distinct syndrome under the affective disorders. Finally, based on this evaluation of the current evidence, the investigators give an outline for a redefinition of PD for the upcoming 11th revision of the International Classification of Disease (ICD-11), which is due in 2015. PD is characterized by the presence of delusions and/ or hallucinations in addition to depression.

A typical case is a patient displaying anhedonia, psychomotor retardation, loss of interest, poor concentration and who is tormented by delusions of guilt, disease, worthlessness or impending disaster. PD has a characteristic symptomatology which, apart from the psychotic features, involves a psychomotor disturbance (either agitation or retardation), rumination, insomnia, cognitive dysfunction and perplexity more often than non-PD. Regarding the course of disease, PD is associated with increased long-term psychosocial impairment, increased rates of relapse and higher levels of mortality compared to non-PD, possibly due to increased risk of suicide.

One of the arguments raised by the DSM-IV Work Group on Mood Disorders against the classification of PD as a distinct entity was that the number of psychiatric syndromes was already too high, but since PD is a rather prevalent disorder and already defined in the diagnostic manuals, this argument seems misplaced in the discussion of defining PD as a distinct diagnostic syndrome. Another counterpoint to PD being a distinct syndrome concerns the relationship between the severity of depression and the presence of psychosis. It has been suggested that the differences between PD and non-PD could reflect mere differences in depressive severity.

However, recent findings have demonstrated that episodes of PD are not necessarily ‘severe’ according to the number of depressive symptoms and that patients without any history of psychosis may experience nonpsychotic depressive episodes of greater symptom severity compared to psychotic depressive episodes in patients with PD. Another counterpoint to PD being a distinct syndrome concerns the stability of the diagnosis. A very recent study has caused reason to question the validity of PD due to its finding of low diagnostic stability over 10 Years.

However, changes in diagnoses over time and so-called diagnostic drift exists for all mental disorders and for virtually all diseases in general. Depression is heritable, but among the less heritable of the mental disorders, where schizophrenia and bipolar disorder lie at the other end of the spectrum. However, studies have indicated that the heritability of PD is stronger than that of non-PD and that PD displays considerable specificity in familial transmission.