The role of hemispheric lateralisation in immunity & human immunodeficiency virus Type 1 (HIV-1)

Abstract

Neuromodulation of the immune system has been described to be influenced by hemispheric lateralisation (HL), the stable tendency to relatively utilise one hemisphere or its functions over another. To date there has not been a systematic review of research in this phenomenon conducted, and only one study has examined the effects of HL on the progression of a disease – Human Immunodeficiency Virus (HIV). That research was conducted on a small sample with little control for confounders. The present work sought to compile a systematic review of literature concerning HL and immunity in humans, using effect size analysis. Further, the present work also describes an empirical advancement of this earlier HIV study with stricter control over confounds in a larger sample. The findings corroborated the theory of asymmetrical immune influence by HL via the systematic review showing clear, relatively consistent and strong relationships between left-HL and immunopotentiation. The empirical prospective study extended current knowledge of this relationship in HIV to identify a moderator – HAART treatment. Specifically, left-HL predicted better immunity in HIV-1 patients independent of confounders, with further findings of the same pattern in untreated patients, but not in HAART-treated patients. Further observations were made between HL and HIV-relevant behaviours, again adding to current knowledge. The finding of left-HL being associated with fewer sexual partners in Europeans presents new information of relevance to public health. The combined findings of the present work suggest that left-HL has predictive value in illness (HIV-1) and in general immunity. The present work adds to the existing knowledge new information concerning a moderating factor of the HLimmunity relationship in HIV, and behavioural implications of HL which impact upon HIV disease. Potential explanations for moderation, proposals for neurobiological mechanisms and direction towards future, more rigourous study in the field, both in HIV and immunity, are discussed.