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Objectives: To review the evidence of the involvement of the Wnt signalling pathway in mood disorders and in the action of drugs used to treat these disorders., Methods: We performed a careful PubMed search using as keywords all possible terms relevant to the Wnt pathway and crossing them with each of four areas, i.e., developmental effects, behavioural effects, mood disorders, and drugs used in their treatment. Papers were selected on the basis of their content and their data used for discussion., Results: Neurodevelopmental and behavioural data point to the possibility of involvement of the Wnt pathway in the pathophysiology of mood disorders. Clinical and post-mortem data are not sufficient to corroborate a definite role for Wnt alterations in any mood disorder. Combining genetic and pharmacological data, we may state that glycogen synthase kinase is the key molecule in bipolar disorder, as it is connected with many other signalling pathways that were shown to be involved in mood disorders, while Wnt molecules in the hippocampus appear to be mainly involved in depressive disorders., Conclusions: Altered Wnt signalling may play a role in the pathophysiology of mood disorders, although not a central one. It is premature to draw conclusions regarding the possible usefulness of Wnt manipulations in the treatment of mood disorders.

Background: Dickkopf-1 (DKK1) is an inhibitor of the canonical Wnt pathway, which is known to be impaired in both psychotic and neurodegenerative disorders. Here, we examined serum DKK1 levels as an indicator of ongoing neurodegeneration in psychotic patients, with or without a recent or current history of drug abuse., Methods: We measured serum DKK1 levels by ELISA in 22 inpatients with psychosis and no history of drug abuse, 22 with psychosis and drug abuse, and 16 controls. We rated psychopathology using the following rating scales: the Positive and Negative Syndrome Scale (PANSS); the Clinical Global Impressions (CGI) severity scale; and the Global Assessment of Functioning (GAF) scale. Extrapyramidal motor symptoms were assessed by the Simpson-Angus Neurological Rating Scale (NRS)., Results: Inpatients with psychosis and comorbid substance abuse showed significantly higher serum DKK1 levels than inpatients with psychosis and no comorbid substance abuse or controls. Comorbid patients had earlier onset, longer duration of psychosis, and more severe extrapyramidal motor symptoms. However, we did not find any significant correlation between DKK1 levels and rating scale scores., Conclusion: Psychosis led to elevated serum DKK1 levels, and substance abuse led to a further increase. Knowing that there is a correlation between brain and blood levels of DKK1, we speculate that the observed increase in DKK1 levels reflects drug-induced neurotoxicity in our patients., (Copyright © 2011 Elsevier Inc. All rights reserved.)