Historically, terrorists have overwhelmingly been young adults. Direct involvement in terrorist attacks is associated with people in their 20s and 30s, with those in leadership positions slightly older (30s and 40s). The composition of the so-called Islamic State, however, defies the idea of even a generic demographic profile. While the Islamic State now manufactures child soldiers, preliminary evidence suggests an emerging and increasingly aggressive role for older adults (aged 60 and beyond), especially as suicide bombers. The Islamic State has produced not only the youngest suicide bombers in history, but now also the oldest. As pressure intensifies on the movement, this trend will likely continue.
Horgan, John, Mia Bloom, Chelsea Daymon, Wojciech Kaczkowski, and Hicham Tiflati. 2017. "A New Age of Terror? Older Fighters in the Caliphate." CTC Sentinel 10 (May): 13-19. https://www.ctc.usma.edu/v2/wp-content/uploads/2017/05/CTC-Sentinel_Vol10Iss511.pdf