[Antidepressants are frequently prescribed but still critized; a perspective on causes and solutions]. / Antidepressiva: al decennia voor­geschreven én toch nog steeds bekritiseerd; een perspectief op oorzaken en oplossingen.

BACKGROUND: From around 1980, antidepressants (ad) have increasingly been prescribed, for longer periods of time, especially selective serotonin reuptake inhibitors (ssris). Paradoxically, their effectiveness is still doubted, especially outside the psychiatric profession.
AIM: To explain increase and offer a perspective on causes and solutions, and to indicate how to reach consensus.
METHOD: Position paper with critical analysis and synthesis of relevant literature.
RESULTS: The rise in AD prescriptions results from: 1. increased safety and ease of prescribing, 2. increased presentation and recognition of depression in primary care, 3. extension of indication criteria, 4. effective marketing strategies, and 5. effectiveness in acute phase (aad) and of relapse/recurrence prevention in continuation/maintenance phases (coad).Critics point to: 1. low added value of aad relative to placebo, 2. many drop-outs and non-responders, 3. relapse/recurrence prevention with coad works only for responders to aad, 4. relapse/recurrence after AD discontinuation often involves withdrawal symptoms, and 5. publication bias, selective reporting, selective patient selection, and suboptimal blinding, resulting in overestimated effectiveness and underestimated disadvantages.Factors that keep fueling the controversy are: 1. critics stress the net effectiveness of AD whereas proponents point at gross effectiveness which includes spontaneous recovery and placebo effect; 2. persistence of distrust in industry-funded rcts; 3. ideological positions, reinforced by conflicts of interest and selective citations; 4. lack of rcts with relevant long-term outcome measurements.
CONCLUSION: Although consensus is difficult to achieve given the ideological component, there are options. Three factors are critically important: confer to establish which data convince the opposition, response prediction (what works for whom), and rcts with long-term functional outcomes.

Kinds versus continua: a review of psychometric approaches to uncover the structure of psychiatric constructs.

The question of whether psychopathology constructs are discrete kinds or continuous dimensions represents an important issue in clinical psychology and psychiatry. The present paper reviews psychometric modelling approaches that can be used to investigate this question through the application of statistical models. The relation between constructs and indicator variables in models with categorical and continuous latent variables is discussed, as are techniques specifically designed to address the distinction between latent categories as opposed to continua (taxometrics). In addition, we examine latent variable models that allow latent structures to have both continuous and categorical characteristics, such as factor mixture models and grade-of-membership models. Finally, we discuss recent alternative approaches based on network analysis and dynamical systems theory, which entail that the structure of constructs may be continuous for some individuals but categorical for others. Our evaluation of the psychometric literature shows that the kinds-continua distinction is considerably more subtle than is often presupposed in research; in particular, the hypotheses of kinds and continua are not mutually exclusive or exhaustive. We discuss opportunities to go beyond current research on the issue by using dynamical systems models, intra-individual time series and experimental manipulations.

The pathoplasticity of dysphoric episodes: differential impact of stressful life events on the pattern of depressive symptom inter-correlations.

BACKGROUND: Previous research has shown that stressful life events (SLEs) influence the pattern of individual depressive symptoms. However, we do not know how these differences arise. Two theories about the nature of psychiatric disorders have different predictions about the source of these differences: (1) SLEs influence depressive symptoms and correlations between them indirectly, via an underlying acute liability to develop a dysphoric episode (DE; common cause hypothesis); and (2) SLEs influence depressive symptoms and correlations between them directly (network hypothesis). The present study investigates the predictions of these two theories. METHOD: We divided a population-based sample of 2096 Caucasian twins (49.9% female) who reported at least two aggregated depressive symptoms in the last year into four groups, based on the SLE they reported causing their symptoms. For these groups, we calculated tetrachoric correlations between the 14 disaggregated depressive symptoms and, subsequently, tested whether the resulting correlation patterns were significantly different and if those differences could be explained by underlying differences in a single acute liability to develop a DE. RESULTS: The four SLE groups had markedly different correlation patterns between the depressive symptoms. These differences were significant and could not be explained by underlying differences in the acute liability to develop a DE. CONCLUSIONS: Our results are not compatible with the common cause perspective but are consistent with the predictions of the network hypothesis. We elaborate on the implications of a conceptual shift to the network perspective for our diagnostic and philosophical approach to the concept of what constitutes a psychiatric disorder.