No Correlation between Lithium Serum Levels and Psychopathological Features during the Euthymic Interval of Patients with Recurrent Affective Disorder

Abstract

The aim of this prospective study was to investigate the influence of lithium serum levels on subclinical psychopathological features during the euthymic interval in patients with an affective disorder. The study included 54 patients with a recurrent affective disorder undergoing a continuous prophylactic lithium treatment (31 unipolar, 23 bipolar). The observation period lasted for 2 years and included 332 visits. Visits consisted of a detailed interview, a continuous measurement of lithium levels and the collection of validated scales including HAMD, YMRS, CGI, VAMS and the SCL-90R. Several correlations between lithium serum levels and different psychopathological features during the euthymic interval were calculated on an individual patient basis and on a group basis to reveal generally occurring correlations. No generally occurring significant correlations between lithium serum levels and specific psychopathological features were found. Only on a single patient level, 32 significant correlations between lithium level and specific psychopathological features were found, partly indicating a negative and partly indicating a positive influence of higher lithium levels on psychopathological symptoms. Nevertheless, in the group analyses no significant correlations were found. Higher lithium levels were not associated with an improved psychopathological status, but they were not associated with a worse status (due to a higher burden of side effects) either. According to the literature there is currently no strong evidence to treat patients with a higher lithium level. It is recommended to start with a lower level and to continue with individual adjustments in accordance to prophylactic efficacy and tolerability.