Prevalence of respiratory symptoms: marked differences within a small geographical area.

BACKGROUND: Geographical differences in prevalence of respiratory symptoms have been reported between countries in the EC Respiratory Health Survey (ECRHS). The differences between two neighbouring centres in the Antwerp area were surprising. We therefore extended the screening phase of this study to four other areas with different features in this region. METHODS: Methods and questionnaires of the first phase of the ECRHS were used to estimate prevalence rates of respiratory symptoms in all areas. Information on some major personal and environmental risk factors was also obtained. RESULTS: Higher prevalence rates of both respiratory symptoms and personal risk factors were recorded in Urban Antwerp, Berendrecht-Zandvliet (harbour area) and Zwijndrecht (industrial area) than in Suburban Antwerp, Essen and Kasterlee (both rural). Neither personal nor environmental risk factors could provide satisfactory explanations for the area differences in symptoms. CONCLUSIONS: These large differences between groups of subjects living within a small geographical area prove that estimations of prevalence rates of a whole country based on measurements of prevalence in one specific area should be interpreted very cautiously. Epidemiological research within small geographical areas may thus still prove as informative as comparisons between countries for elucidating causes for different asthma prevalence.

Verbal-to-manual and manual-to-verbal dual-task interference in left-handed and right-handed adults.

Verbal-manual interference was investigated with 80 students who were divided into four groups by sex and hand preference. Unilateral finger-tapping was measured during no-load conditions and during two concurrent tasks of word reading (aloud) and sentence reading (silent). During concurrent tasks, no selective interference effects for the preferred hand were found; however, when participants were classified according to consistent handedness instead of hand preference, consistent right-handers exhibited selective right-hand tapping interference during concurrent word reading, whereas consistent left-handers showed generalized interference. During concurrent sentence reading, men showed selective right-hand interference, irrespective of handedness. The influence of tapping on word reading was also examined. Concurrent tapping lowered word-reading performance substantially, showing that finger-tapping and word reading interfered reciprocally.