Unique contributions of anxiety, stress and depression to immunity: A cross-cultural investigation

While immunity and psychological distress are strongly associated, studies seldom consider how different types of distress relate to immune functioning. The literature tends to emphasis the impact of stress on immunity. The present cross-sectional study estimated the unique contributions of depression, anxiety, and stress on immune function in culturally diverse samples of adults from Italy, New Zealand and India. Participants were Italian (n = 1061), New Zealand (n = 1037), and Indian (n = 384) volunteers. Stepwise multiple linear regression and dominance analysis were used to analyse differences in immunity uniquely explained by anxiety, depression, and stress. While samples from the three countries differed significantly, anxiety consistently explained the greatest proportion of differences in immunity. After accounting for the effect of anxiety, stress and depression explained only negligible variation in immune functioning. This association of anxiety with immune functioning was consistent across three different countries and this unique impact was further confirmed by the results of dominance analysis. These findings suggest a clear link between anxiety and immunity, which advances the prevailing stress-disease model and foster further experimental and longitudinal research into the impact of anxiety on immunity.