Effect of insulin sensitivity on corticolimbic responses to food picture in women with polycystic ovary syndrome.

OBJECTIVE: Insulin is one of several molecules that transmit information about energy balance to the brain. It has been hypothesized that insulin resistance fosters non-homeostatic eating. The objective of the current study was to characterize corticolimbic brain responses to appetitive stimuli in subjects with insulin sensitivities ranging from resistant to normal. DESIGN AND METHODS: Sixteen women diagnosed with polycystic ovary syndrome (PCOS) underwent functional magnetic resonance imaging (fMRI) while viewing pictures of high calorie (HC) foods, low calorie (LC) foods, and control (C) pictures. RESULTS: A region of interest analysis of the blood oxygen level dependent (BOLD) signal revealed widespread activation within corticolimbic regions in response to food pictures. Activated regions included the dorsolateral prefrontal cortex (DLPFC), medial prefrontal cortex (mPFC) , insula, nucleus accumbens (NAc), pallidum, ventral tegmental area (VTA), putamen, amygdala, caudate, substantia nigra, hippocampus, pulvinar, and midbrain. Activation of the anterior cingulate, dorsolateral prefrontal cortex (DLPFC), and midbrain by HC food pictures (HC - C) and activation of the lateral orbitofrontal cortex (OFC), pallidum, substantia nigra, ventral tegmental area (VTA), pulvinar, and midbrain by LC food pictures (LC - C) was negatively correlated with insulin sensitivity. In contrast, activation of the OFC, DLPFC, insula, hypothalamus, pallidum, substantia nigra, VTA, pulvinar, and midbrain by the HC - LC contrast was positively correlated with insulin sensitivity, whereas activation of the caudate was negatively correlated. CONCLUSIONS: The association between insulin sensitivity and corticolimbic responses to food pictures may reflect abnormal brain responses to insulin feedback that contribute to the development and or perpetuation of obesity in PCOS.

Seasonal trends in adolescent pregnancy conception rates.

STUDY OBJECTIVE: The objectives of this study were to determine if a seasonal trend exists in adolescent pregnancies and to compare the teen conception rate per month to an adult population. SETTING: The study was conducted in a tertiary care Canadian hospital that has a one-site model of care. DESIGN: A retrospective chart review of all adolescent pregnancies over a 5-year period (N = 838) was undertaken. From the 13,554 adult pregnancies over the same time period, a random sample of 838 pregnancies was chosen for similar chart review. A chi-square test was used to compare the proportion of pregnancies conceived in each calendar month between the two groups. PARTICIPANTS: Pregnancies ending in spontaneous abortions, elective terminations, ectopic pregnancies, as well as obstetrical deliveries, were included. RESULTS: There was a significantly different monthly trend seen in adolescent pregnancy conceptions when compared with the adult group (χ² = 24.38, df = 11, P = 0.0112). The adolescent group was observed to have a unique peak in the number of pregnancies conceived in March (10.5% of pregnancies conceived compared to 7.3% in adults). In addition, 8.5% of conceptions in adolescents occurred in December compared to 10.4% in adults. CONCLUSIONS: There are several plausible explanations for the modest but real differences identified in this study including trends in fecundity/fertility or social/school events that lead to increased sexual activity. Peaks in conception indicate times when a greater need for health care services exists, and when preventive education can be most effective.