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Brain Connect. 2016 Nov;6(9):700-713. Epub 2016 Sep 30.

Sex and Age Effects of Functional Connectivity in Early Adulthood.

Author information

1 Autism and Developmental Medicine Institute , Geisinger Health System, Lewisburg, Pennsylvania.
2 Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology , Rochester, New York.
3 School of Mathematical Sciences, Rochester Institute of Technology , Rochester, New York.
4 Institute for Advanced Application , Geisinger Health System, Danville, Pennsylvania.
5 Department of Child and Adolescent Psychiatry, Erasmus MC-Sophia Children's Hospital , Rotterdam, The Netherlands .
6 Faculty of Science, University of Manitoba , Winnipeg, Manitoba, Canada .


Functional connectivity (FC) in resting-state functional magnetic resonance imaging (rs-fMRI) is widely used to find coactivating regions in the human brain. Despite its widespread use, the effects of sex and age on resting FC are not well characterized, especially during early adulthood. Here we apply regression and graph theoretical analyses to explore the effects of sex and age on FC between the 116 AAL atlas parcellations (a total of 6670 FC measures). rs-fMRI data of 494 healthy subjects (203 males and 291 females; age range: 22-36 years) from the Human Connectome Project were analyzed. We report the following findings. (1) Males exhibited greater FC than females in 1352 FC measures (1025 survived Bonferroni correction; [Formula: see text]). In 641 FC measures, females exhibited greater FC than males but none survived Bonferroni correction. Significant FC differences were mainly present in frontal, parietal, and temporal lobes. Although the average FC values for males and females were significantly different, FC values of males and females exhibited large overlap. (2) Age effects were present only in 29 FC measures and all significant age effects showed higher FC in younger subjects. Age and sex differences of FC remained significant after controlling for cognitive measures. (3) Although sex [Formula: see text] age interaction did not survive multiple comparison correction, FC in females exhibited a faster cross-sectional decline with age. (4) Male brains were more locally clustered in all lobes but the cerebellum; female brains had a higher clustering coefficient at the whole-brain level. Our results indicate that although both male and female brains show small-world network characteristics, male brains were more segregated and female brains were more integrated. Findings of this study further our understanding of FC in early adulthood and provide evidence to support that age and sex should be controlled for in FC studies of young adults.


age effects; early adulthood; fMRI; functional connectivity; resting-state fMRI; sex effects

[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Author Disclosure Statement The authors have no commercial associations that might create a conflict of interest in connection with this article. This study used data publicly available from the Human Connectome Project. The analysis of this study was approved by the Geisinger Health System Institutional Review Board.

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