Just came across this systematic review and metanalysis that is relevant to the interests of this group:
Kishita, N., & Laidlaw, K. (2017). Cognitive behaviour therapy for generalized anxiety disorder: Is CBT equally efficacious in adults of working age and older adults? Clinical Psychology Review, 52, 124–136. http://doi.org/10.1016/j.cpr.2017.01.003
https://doi.org/10.1016/j.cpr.2017.01.003
The basic finding is that whilst there are no statistical diffferences between outcomes for older or working age adults, the effect size for working age adults is almost twice that of for older adults. The review also examines the protocols of the studies with older adults and determines if gerontologically appropriate adaptations have been made, and finds that in the majority of cases this has not been done. Overally the article suggests that GAD treatment in Older Poeple can be improved and incorporating well described adaptations from gernotlogical theory into protocols is one way to test this.