Background: Earlier studies have found that transthyretin (TTR) is reduced in cerebrospinal fluid (CSF) from patients with major depressive disorder and that levels correlate negatively with suicidal ideation. The purpose of this study was to examine CSF-TTR in a cohort of suicide attempters with different psychiatric diagnoses and to further assess the relationship between CSF-TTR and suicidal behaviour as well as psychiatric symptoms.
Methods: TTR was measured using enzyme-enhanced Mancini. Diagnostics were performed with the Diagnostic and Statistical Manual of Mental Disorders. Psychiatric symptoms and suicidal behaviour were rated using the Comprehensive Psychopathological Rating Scale (CPRS), the Suicide Assessment Scale and the Suicidal Intent Scale.
Results: We found no significant difference in CSF-TTR levels between groups of different psychiatric diagnoses and controls. CSF-TTR correlated negatively to the CPRS item 17, "failing memory". No significant correlations between CSF-TTR and suicidal behaviour or suicide intent were found.
Limitations: Correlation analysis is an indirect method of investigation and does not demonstrate causal relationships.
Conclusions: We conclude that CSF-TTR is unlikely to be relevant for suicidal behaviour and that further studies in non-suicidal psychiatric patients are needed before a role of CSF-TTR in depression can be established.