PERFORMANCE POSSIBLE IMPLICATIONS

OF NERVOUS SYSTEM AND IMMUNE SYSTEM LINKS IN

SPORTS REHABILITATION

Therapeutic interventions in medicine have traditionally been divided into the physical (eg. surgery and physiotherapy) and the mental (eg. cognitive therapy and psychoanalysis). This dichotomy is perhaps more a reflection of the historical context and evo- lution of various treatment modalities than a reflection of any true divide between mental health/function and physical health/function at the biological level. In fact, evidence suggesting that ‘physical’ treatments may have significant implications for mental functioning and vice-versa is mounting. This article is the first of a two-part series examining links between mind and body, and how these might be of significance and utilised within the sports rehabilitation process.

The article describes some mechanisms by which psychological processes might influence immune system function, the focus of the developing interdisciplinary field of psychoneuroimmunology (PNI), and how these interactions might be utilised by thera- pists. The reciprocal effect, that of the potential for immune system influence on psychological processes, is not addressed in the present article. A second article in the next issue will examine how beliefs in treatment efficacy and outcomes (of both the patient and practitioner) may in fact be critical to the overall outcome of that treatment. The purpose of the current article is to a certain extent speculative; that is, to the authors’ knowledge, no published research has explicitly linked the fields of sports rehabilitation and PNI. However, it is hoped that the proposals below have an intuitive appeal to practitioners, and that they may resonate in the light of some readers’ experience.

By James Hopker BSc and Dr Chris Beedie PhD

EVIDENCE FOR INTERACTION BETWEEN THE NERVOUS AND IMMUNE SYSTEMS Empirical evidence for a functional link between the nervous system and the immune system was initially presented by Ader and Cohen (1), who ‘discovered’ it somewhat fortuitously while examining conditioned taste aversion in rats. Their protocol paired a novel taste (sugar water) with an immunosuppressant (cyclophosphamide). When exposed to the conditioned stimulus (sugar water) alone, the rats showed significant immunosuppres- sion - in fact many rats died - suggesting a conditioned immune system response. These results, which were initially greeted with

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considerable scepticism by the scientific community, suggested a bi-directional link between the central nervous system and the immune system.

Descriptive evidence for a neural-immune link was supplied by Kiecolt-Glaser et al. (2), who reported that students experiencing exam-related stress and stressful life events experienced signifi- cantly reduced levels of natural killer cell activity than during a non-examination period. Significantly, the authors reported that loneliness exacerbated the decrease in natural killer cell activity. Perhaps related to these results, epidemiological studies of mortality (3), have shown high levels of social support to be consistently associated with diminishing risk of morbidity and

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