Abstract
This thesis explored whether individual differences in taste perception (as measured by the rated intensity of 6-n-propylthiouracil (PROP) were associated with tobacco use, alcohol use and misuse and obesity in the Dunedin Multidisciplinary Health and Development Study birth cohort at age 32. This cohort of 1,037 participants was assessed at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26 and, most recently, at 32 years, when 96% of the living study members were interviewed. At age 32, participants rated the intensity of a 0.0032mol/L solution of PROP using the general labelled magnitude scale (gLMS). PROP is almost tasteless to some but tastes bitter to others. As bitter tastes are aversive, due to their association with toxicity, it has been suggested that responses to PROP may reflect individual differences in taste perception that, in turn, have a protective effect on health. Study One sought to establish correlates of rated PROP intensity in this sample. A model controlling for sex, childhood socio-economic status (SES), childhood IQ and gLMS use predicted approximately 12% of the variability in PROP ratings. This finding highlighted the importance of using appropriate covariates in research attempting to link PROP perception with health risk behaviours, as these factors have also been associated with tobacco use, alcohol use and adiposity. Study Two did not find that greater perceived intensity from PROP was protective against smoking, as pack years smoked was not associated with PROP rating and ratings between groups of smokers were not significantly different. Differences in PROP perception were not protective against the lifetime smoking in this sample. Similarly, Study Three found no evidence to suggest that greater intensity from PROP was associated with reduced alcohol misuse. Furthermore, the previously observed association between PROP and yearly alcohol consumption may be better explained by the fact that SES accounts for some of the variance in both measures. In Study Four, rated PROP intensity was associated with Body Mass Index (BMI), waist circumference and body fat percentage, in women, but not in men. These associations were weakened after the inclusion of covariates in the models, but remained significant for both BMI and body fat percentage. Findings from Study Four indicate that taste perception may be associated with measures of adiposity in women. Taken together, these results highlight the importance of using appropriate control variables in research and indicate that a single measure of PROP perception may not adequately reflect the full effect of individual differences in taste perception on tobacco use or alcohol use and misuse. Since PROP perception was associated with differences in adiposity in women, however, individual differences in taste perception may be of public health importance. Future research should use continuous measures of a wider range of taste stimuli, to establish how taste perception (rather than just bitterness perception) affects health. Research should also ensure that covariates associated with tobacco use, alcohol use and misuse and adiposity (such as sex, SES and IQ) are included in analyses.