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OBJECTIVE Antidepressants that increase serotonin or norepinephrine in the brain are effective in treating depression, but there is no neuropsychological account of how these changes relieve depressive states. Cognitive theories suggest that biases in information processing lead depressed patients to make unrealistically negative judgments about themselves(More)
OBJECTIVE Antidepressants that inhibit the reuptake of serotonin (SSRIs) or norepinephrine (SNRIs) are effective in the treatment of disorders such as depression and anxiety. Cognitive psychological theories emphasize the importance of correcting negative biases of information processing in the nonpharmacological treatment of these disorders, but it is not(More)
Enhancement of serotonin neurotransmission plays an important role in the antidepressant response to agents presently available to treat depression. This response forms the major evidence for the role of serotonin in affective and social behaviour in humans. The present study investigated the effects of acute administration of the selective serotonin(More)
BACKGROUND The amygdala is believed to play a key role in processing emotionally salient, threat-relevant, events that require further online processing by cortical regions. Emotional disorders such as depression and anxiety have been associated with hyperactivity of the amygdala, but it is unknown whether antidepressant treatment directly affects amygdala(More)
BACKGROUND We have previously shown that single doses of serotonin-selective and noradrenaline-selective antidepressant agents produce positive biases in measures of emotional processing in healthy volunteers. The aim of the present study was to confirm and extend this finding by studying the effects of a single dose of the selective serotonin and(More)
Acute tryptophan depletion (ATD) induces depressive symptoms in 50-60% of selective serotonin reuptake inhibitor (SSRI) treated, recovered depressed patients. However, no reliable predictors of mood response to ATD have been established. In the present study, individual subject data of six ATD studies were pooled ('mega-analysis') in order to investigate(More)
BACKGROUND Pharmacological and postmortem investigations suggest that patients with major depressive disorder have alterations in function or density of brain serotonin1A (5-HT1A) receptors. The aim of the present study was to use positron emission tomography with the selective 5-HT1A receptor antagonist [11C]WAY-100635 to measure 5-HT1A receptor binding in(More)
BACKGROUND The neuropharmacological actions of antidepressants are well characterised but our understanding of how these changes translate into improved mood are still emerging. AIMS To investigate whether actions of antidepressant drugs on emotional processing are a mediating factor in the effects of these drugs in depression. METHOD We examined key(More)
BACKGROUND Major depression is a common disorder but the pathophysiology is poorly understood. Current hypotheses implicate deficient function of brain serotonin pathways because drugs that selectively increase brain serotonin activity are effective antidepressants. However, there is no direct evidence that lowered serotonin function causes major(More)
We report the effects of a tyrosine (and phenylalanine)-free amino acid mixture on tyrosine levels, ex vivo catecholamine synthesis and in vivo catecholamine release in brain regions of the rat. Administration of a tyrosine-free amino acid load reduced tissue levels of tyrosine (-50% after 2 h) in all brain regions examined (frontal cortex, hippocampus,(More)