Increasing association between a neuropeptide Y promoter polymorphism and body mass index during the course of development.

OBJECTIVE: To investigate the association of the neuropeptide Y (NPY) promoter polymorphism rs16147 with body mass index (BMI) during the course of development from infancy to adulthood. DESIGN: Longitudinal, prospective study of a German community sample. SUBJECTS: n = 306 young adults (139 males, 167 females). MEASUREMENTS: Participants' body weight and height were assessed at the ages of 3 months and 2, 4.5, 8, 11, 15 and 19 years. NPY rs16147 was genotyped. RESULTS: Controlling for a number of possible confounders, homozygote carriers of the rs16147 C allele exhibited significantly lower BMI scores when compared with individuals carrying the T allele. In addition, a significant genotype by age interaction emerged, indicating that the genotype effect increased during the course of development. CONCLUSIONS: This is the first longitudinal study to report an association between rs16147 and BMI during childhood and adolescence. The finding that this effect increased during the course of development may either be due to age-dependent alterations in gene expression or to maturation processes within the weight regulation circuits of the central nervous system.

Cigarette craving increases after a psychosocial stress test and is related to cortisol stress response but not to dependence scores in daily smokers.

Stress is known to induce cigarette craving in smokers, but the underlying mechanisms are widely unknown. We investigated how dependence severity, smoking habits and stress-induced cortisol secretion are associated with increased cigarette craving after a standardised laboratory stressor. Hundred and six healthy participants (50 men, age 18-19 years) underwent a standardised public speaking stress task. In all, 35 smoked daily (DS), 13 smoked occasionally (OS), and 58 never smoked (NS). Smoking was unrestricted until 2 h before stress onset. Plasma cortisol was measured before and up to 95 min after the stressor. All current smokers rated intensity of cigarette craving immediately before and immediately after the stressor using the Brief Questionnaire of Smoking Urges (BQSU). Cortisol levels significantly increased in response to stress in all groups. The magnitude of this stress response was significantly lower in DS compared with OS and NS but did not differ between OS and NS. Baseline BQSU scores were significantly higher in DS than OS. BQSU scores increased significantly during the stress period and were positively correlated to the cortisol response in the DS but were unrelated to their nicotine dependence scores. In OS, no change in cigarette craving could be observed. In daily smokers, cigarette craving is increased after compared with before stress exposure and is related to the magnitude of cortisol stress response rather than to severity of nicotine dependence. This result supports, but does not prove, the concept that hypothalamus-pituitary-adrenal stimulation is one of the mechanisms how stress can elicit cigarette craving.