Sustained attention deficits in euthymic bipolar patients

Background: Sustained attention deficits are proposed to be both state and trait indicators of bipolar disorder. The results of studies evaluating attention of bipolar patients are inconsistent. Most of them assessed patients in acute episodes of affective illness. In euthymic bipolar patients some authors reported attention deficits and regarded them as one of core features of bipolar disorder (BD), others have not reported attention disturbances. The aim of this study was to assess sustained attention in patients with bipolar disorder in remission using Rapid Visual Processing Test (RVIP) from Cambridge Automated Neuropsychological Test Battery (CANTAB). Material and methods: Ninety-eight patients with bipolar disorder in remission lasting for at least 4 months diagnosed according to ICD-10 criteria and ninety healthy controls entered the study. Duration of illness was at least 5 years and prophylactic treatment lasted for at least 2 years. Sixty patients were treated with lithium and 38 with other mood stabilizers. Mental state of patients was assessed using Hamilton Depression Rating Scale (HAMD), and Young Mania Scale (YMS). All included bipolar patients met criteria of remission -HAMD < 8 and YMS < 6. Results: Bipolar patients showed significantly worse sensitivity to the target (A') and longer reaction time than healthy controls. Lithium treated patients and patients taking other mood stabilizers showed worse differentiation between signals and noise and longer time of reaction than controls. In the lithium group serum level of lithium showed positive correlation with time of reaction and negative correlation with total hits number and total correct rejections. A target sensitivity was negatively correlated with a duration of illness and mean latency was positively correlated with the age of patients, a duration of illness as well as a number of reccurences. Conclusions: The results of the study point to the persistence of sustained attention deficits in remission of bipolar disorder. Bipolar patients treated with lithium in combination with other drugs scored less in RVIP than remaining patients.