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IntroductionThe reporting of approaches facilitating the most efficient and timely recruitment of Alzheimer's disease (AD) patients into pharmacologic trials is fundamental to much-needed therapeutic progress.MethodsT2 Protect AD (T2), a phase 2 randomized placebo-controlled trial of troriluzole in mild to moderate AD, used multiple recruitment strategies.ResultsT2 exceeded its recruitment target, enrolling 350 participants between July 2018 and December 2019 (randomization rate: 0.87 randomizations/site/month, or 3-fold greater than recent trials of mild to moderate AD). The vast majority (98%) of participants were enrolled during a 10-month window of intense promotion in news media, TV and radio advertisements, and social media. The distribution of primary recruitment sources included: existing patient lists at participating sites (72.3%), news media (12.3%), physician referral (6.0%), word of mouth (3.1%), and paid advertising (2.9%).DiscussionThe rapid recruitment of participants with mild to moderate AD was achieved through a range of approaches with varying success.

IntroductionEffective strategies to recruit older adults with mild cognitive impairment (MCI) into nonpharmacological intervention trials are lacking.MethodsRecruitment for EXERT, a multisite randomized controlled 18-month trial examining the effects of aerobic exercise on cognitive trajectory in adults with amnestic MCI, involved a diverse portfolio of strategies to enroll 296 participants.ResultsRecruitment occurred September 2016 through March 2020 and was initially slow. After mass mailings of 490,323 age- and geo-targeted infographic postcards and brochures, recruitment rates increased substantially, peaking at 16 randomizations/month in early 2020. Mass mailings accounted for 52% of randomized participants, whereas 25% were recruited from memory clinic rosters, electronic health records, and national and local registries. Other sources included news broadcasts, public service announcements (PSA), local advertising, and community presentations.DiscussionAge- and geo-targeted mass mailing of infographic materials was the most effective approach in recruiting older adults with amnestic MCI into an 18-month exercise trial.

Females and males have distinct trait optima, resulting in selection for sexual dimorphism. However, most traits have strong cross-sex genetic correlations, which constrain evolutionary divergence between the sexes and lead to protracted periods of maladaptation during the evolution of sexual dimorphism. While such constraints are thought to be costly in terms of individual and population fitness, it remains unclear how severe such costs are likely to be. Building upon classical models for the ‘cost of selection’ in changing environments (sensu Haldane), we derived a theoretical expression for the analogous cost of evolving sexual dimorphism; this cost is a simple function of genetic (co)variances of female and male traits and sex differences in trait optima. We then conducted a comprehensive literature search, compiled quantitative genetic data from a diverse set of traits and populations, and used them to quantify costs of sexual dimorphism in the light of our model. For roughly 90% of traits, costs of sexual dimorphism appear to be modest, and comparable to the costs of fixing one or a few beneficial substitutions. For the remaining traits (approx. 10%), sexual dimorphism appears to carry a substantial cost—potentially orders of magnitude greater than costs of selection during adaptation to environmental changes.