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State and trait variance in salivary alpha-amylase: a behavioral genetic study

TitleState and trait variance in salivary alpha-amylase: a behavioral genetic study
Publication TypeJournal Article
Year of Publication2011
AuthorsOut, D, Bakermans-Kranenburg, MJ, Granger, DA, Cobbaert, CM, van Ijzendoorn, MH
JournalBiological psychology
Date PublishedSep
ISBN Number1873-6246; 0301-0511
Accession Number21827821
Keywords*Genetics, Behavioral, Acoustic Stimulation, Adolescent, Adult, Aged, Analysis of Variance, Crying, Electroencephalography, Female, Humans, Individuality, Male, Middle Aged, Models, Biological, Photic Stimulation, Questionnaires, Saliva/*enzymology, Salivary alpha-Amylases/*genetics/*secretion, Sex Factors, Twin Studies as Topic, Young Adult

This is the first behavior genetic study of salivary alpha-amylase (sAA), focusing on genetic and environmental influences on stability and change in sAA during baseline and exposure to infant crying. The sample consisted of 184 adult twin pairs. Although there was significant variation between individuals in basal levels of sAA and in responsivity to infant crying, strong stability in sAA concentrations across conditions was found. Similar genetic mechanisms influenced sAA at baseline and in response to cry sounds (explained variance: 51-62%), accounting for part of the stability in sAA. Unique environmental factors explained the remaining variance in sAA, some of them only emerging in response to the cry sounds, explaining individual differences in the pattern of reactivity. These findings confirm that sAA is sensitive to the effects of potentially stressful stimuli (state variance) and at the same time demonstrate its relative robustness and stability across time and conditions (trait variance).