Mild acute inflammatory stimulation induces transient negative mood

OBJECTIVE: This study aims to assess the mood changes induced by mild acute inflammatory stimulation (typhoid vaccination). METHODS: Using a double blind study design, 26 healthy volunteers underwent baseline assessments of mood, financial strain and work stress and were randomised to injection of Salmonella typhi vaccine or placebo injection. Mood, symptoms and body temperature was assessed by a modified version of the Profile of Mood States at 1, 2, 3, 4, 6 and 8 h post injection. RESULTS: Typhoid vaccination induces no increases in physical symptoms or temperature. Mood improved over the day in the placebo but not in the vaccine condition. Negative changes in mood following injection were correlated with chronic stress (financial strain) in the vaccination condition (r=−.65, P<.025). CONCLUSION: A mild acute inflammatory stimulus induces transient negative mood, and responses were modulated by chronic stress. Implications for depressed mood in physical illness are discussed.