Introduction: 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.
Methods: 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.
Results: 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.
Discussion: 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.
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