Exploratory Aim: Explore the effects of a fronto-temporal structural and functional reserve on CET treatment response. Moderator analyses will examine whether pre-treatment fronto-temporal structural and functional brain reserves (operationalized in Section 3C.8.2) predict larger cognitive and functional gains in CET. Exploratory analyses will also examine the degree to which later (18 mo) treatment improvement is dependent upon early (9 mo) neuroprotection and increased brain function, which may reflect plasticity.