Poster Presentations

Session Title: Inflammation
Presentation Date: Friday, March 14 – Saturday, March 15, 2009

LYMPHOPENIA IN IDIOPATHIC PARKINSONISM: AN AETIOLOGICAL CLUE

J. Bowthorpe¹, A. Charlett², C. Weller¹, R.J. Dobbs³, S.M. Dobbs^3
1Institute of Psychiatry, Kings College London, London, United Kingdom, ²Centre for Infections, Health Protection Agency, London, United Kingdom, ³Institute of Psychiatry, Kings College London, Department of Gastroenterology, Kings College Hospital, London, United Kingdom

Introduction: In idiopathic parkinsonism (IP), small studies report reduced blood lymphocyte count.
Methods:  We contrast lymphocyte counts in 126 IP probands and 79 probands' spouses with general practitioners' routine requests. With 400 controls, standard-deviation of derived reference-range-limits would be small. Age trends in full-blood-count indices of controls < 46 years proved anomalous: exclusion left 381. Lymphocyte counts were examined for distinct Gaussian-distributions (e.g. a subgroup with infection). A mixture of Gaussian-distributions did not provide a better fit.
Results/discussion: Mean lymphocyte count was 23.8 (95% CI 18.7, 28.7)% lower in probands (p< 0.001, after age and gender adjustment) and 17.3 (10.0, 24.0)% lower in 79 spouses (p< 0.001). An estimated 12.5 (7.2, 19.8)% of probands and 7.1 (2.4, 15.9)% of spouses fell below age-specific contemporaneous reference-range cf. expected 2.5% (p< 0.001), no-one exceeding range. Counts were shifted downwards in probands, spouses and controls cf. conventional lower reference-range-limit (1.3 x10⁹/l) by 30.8 (22.7, 39.9), 10.0 (4.1, 19.5) and 7.3 (4.9, 10.4)%, respectively, frequency of 'lymphopenia' varying between groups (p< 0.001).In probands never exposed to anti-parkinsonian medication (37.3%), the count was 101.0 (89.5, 113.9)% of that in spouses, i.e. significantly lower than in controls. Probands receiving medication had a 11.1 (0.1, 20.8)% lower count (p< 0.05). Including time-from-diagnosis in the model reduced significance of medication-status to 0.1. Time-from-diagnosis was not important independently, in either medicated or un-medicated. Intrinsically-linked effects of exposure and time-lapse maybe surrogate for disease-progression.
Conclusion: Robust finding of reduced lymphocyte count in probands and their spouses indicates a shared environmental influence.