Female male female 3,823 human 3,770 Humans 3,769 Male 3,762 adult 2,584 Adult 2,100 middle aged 1,593 Middle Aged 1,587 Article 1,420 controlled study 1,378 young adult 1,278 Young Adult 1,259 adolescent 1,153 Adolescent 1,129 major clinical study 1,057 aged 1,028 Aged 957 physiology 846 child 840 psychology 802 Child 755 procedures 728 article 632 diagnostic imaging 558 questionnaire 437 cross-sectional study 432 retrospective study 423 human experiment 417