Nordic Mensa Fund awarded three article of the year -awards in 2022. Kimmo Sorjonen was awarded for the article "Regression to the mean in latent change score models: an example involving breastfeeding and intelligence" published in BMC Pediatrics.
The study demonstrates nicely the importance of statistical considerations when studying complex relationships between the environment and cognitive abilities. The authors reanalyzed data that show a strong relationship between breastfeeding and an increase in children’s intelligence. This relationship is a popular belief, but as Sorjonen et al. show, this relationship might not exist at all.
Using advanced statistical modelling they show that when analysing change from mothers to children, breastfeeding was found to have a positive association with intergenerational change in intelligence, whereas when analysing backward change from children to mothers, a negative association was found. This finding calls into question the reliability of earlier studies of breastfeeding and intelligence using observational data. The conclusion is that studies of breastfeeding and intelligence must use stronger designs to be able conclude that a causal effect of breastfeeding on intelligence exists.
Kimmo Sorjonen received his PhD from Stockholm University in 2003, on a thesis with the title “For whom is suicide accepted” with Professor Ulf Lundberg as supervisor. Between 2003 and 2006 he held a position as lecturer at Malardalen University College. Since 2004 he has also held a position as assistant project director and then as a lecturer in statistics, philosophy of science, and social psychology at the Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet. Kimmo is a member of the cognitive epidemiology research group, headed by Professor Bo Melin, at Karolinska Institutet. His research has lately focused mainly on statistical artefacts and spurious associations in research on clinical psychology and cognitive abilities.