Affective style and in vivo immune response: neurobehavioral mechanisms

Abstract

Considerable evidence exists to support an association between psychological states and immune function. However, the mechanisms by which such states are instantiated in the brain and influence the immune system are poorly understood. The present study investigated relations among physiological measures of affective style, psychological well being, and immune function. Negative and positive affect were elicited by using an autobiographical writing task. Electroencephalography and affect-modulated eye-blink startle were used to measure trait and state negative affect. Participants were vaccinated for influenza, and antibody titers after the vaccine were assayed to provide an in vivo measure of immune function. Higher levels of right-prefrontal electroencephalographic activation and greater magnitude of the startle reflex reliably predicted poorer immune response. These data support the hypothesis that individuals characterized by a more negative affective style mount a weaker immune response and therefore may be at greater risk for illness than those with a more positive affective style.

Fig. 1.

Scatter plots of baseline activation asymmetry in the frontal pole (A) and lateral frontal (B) scalp regions (right - left alpha power in log μV²/Hz) and antibody titer rise (log₂) to influenza vaccine 6 months postvaccine. Note that higher numbers are associated with greater relative left-sided prefrontal activation. Subjects exhibiting more relative left-sided prefrontal activation both at the frontal pole (A: r = 0.37, P < 0.01, n = 52) and lateral frontal (B: r = 0.38, P < 0.01, n = 47) sites have a larger antibody titer response. (C) Bar graph of the mean antibody titer rise (log₂) to influenza vaccine 6 months postvaccine for groups at the extreme ends of activation asymmetry [t(22) = -4.1, P < 0.01], comprised of individuals in the top and bottom 25th percentiles of asymmetry at the lateral frontal (F7/8) site.

Fig. 2.

Topographical spline-interpolated map of correlation coefficients across the scalp for baseline activation asymmetry (right - left alpha power) and antibody titer rise 6 months postvaccine, demonstrating that the strong positive associations are restricted to brain electrical measures recorded from frontal sites. Positive associations denote that greater relative left-sided activation is associated with higher antibody rise.

Fig. 3.

Scatter plot showing EEG activation asymmetry in the frontal polar scalp region (right - left alpha power in log μV²/Hz) during the negative affect induction and antibody titer rise (log₂) to influenza vaccine 6 months postvaccine. Subjects exhibiting a more left-sided activation asymmetry at the frontal pole (r = 0.45, P < 0.01, n = 36) site have a larger antibody titer response.

Fig. 4.

Scatter plot showing the difference in eye-blink startle reflex magnitude (orbicularis oculi electroencephalograph, μV, z-transformed difference scores) during negative–positive affective induction and immune response to influenza vaccine. Subjects who showed a larger startle response during the negative relative to the positive affect induction showed a smaller antibody response to influenza vaccination (r = -0.50, P < 0.01, n = 29).