Introduction The relationship between brain serotonin and depression is well established. It is also widely accepted that serotonin hyperproduction in carcinoid syndrome does not cross the brain barrier. CNS serotonin is synthesised from tryptophan within serotonergic neurons and a deficiency of this precursor could be possible on carcinoid patients. In this cross-sectional study we evaluated, whether the feelings of depression are associated with neuroendocrine symptomatology. In addition, whether self-report of quality of life is associated with feelings of depression.

Methods 47 patients with carcinoid syndrome completed a survey via clinic involving: QoL questionnaires and the Beck's Depression Inventory-II (BDI-II). All questionnaires were counterbalanced.

Results 45 out of 47 patients had low scores on the BDI-II and not likely to suffer from depression. Only two participants had moderate depression scores. These scores were negatively associated with self-report of QoL, r=−0.59, N=46, p<0.001. Interestingly, endocrine symptoms that is, flushing and night sweats, were not associated with depressive symptoms: r=0.22, N=44, p=0.15, whereas, gastrointestinal symptoms that is, diarrhoea, abdominal discomfort, bloatedness and indigestion, were strongly associated with depression scores: r=56, N=43, p<0.001.

Conclusion Depressive scores in carcinoid patients are often attributed to the stress of diagnoses and adaptation to this chronic disease, however, although a causal relationship has not been established between carcinoid and depression, physicians should consider this possibility when psychological symptoms do not improve with conventional therapy. Further research is needed to understand why gastrointestinal, and not endocrine, symptoms were correlated with depressive symptoms.

Competing interests None declared.

References 1. Lapeire LD, Tansens A, Lemmens G, et al. Carcinoid encephalopathy: A single entity or a spectrum of different disorders. Acta Oncologica 2010;49:268–70.

2. Major LF, LaVonne Brown G, Wilson WP. Carcinoid and psychiatric symptoms. South Med J 1973;66:797–90.

3. Rosenthal MA. Carcinoid associated encephalitis successfully treated with tryptophan. J Clin Neurosci 2004;11:66–7.

4. Williams MD, Dolenic T. Selective serotonin reuptake inhibitors and patients with carcinoid tumor. Psychosomatics 2005;46:370–2.