Increased cerebrospinal fluid interleukin-8 in bipolar disorder patients associated with lithium and antipsychotic treatment

Inflammation has been linked to the pathophysiology of bipolar disorder based on studies of inflammation markers, such as cytokine concentrations, in plasma and serum samples from cases and controls. However, peripheral measurements of cytokines do not readily translate to immunological activity in the brain. The aim of the present study was to study brain immune and inflammatory activity. To this end, we analyzed cytokines in cerebrospinal fluid from 121 euthymic bipolar disorder patients and 71 age and sex matched control subjects. Concentrations of 11 different cytokines were determined using immunoassays. Cerebrospinal fluid IL-8 concentrations were significantly higher in patients as compared to controls. The other cytokines measured were only detectable in part of the sample. IL-8 concentrations were positively associated to lithium- and antipsychotic treatment. The findings might reflect immune aberrations in bipolar disorder, or be due to the effects of medication.