Yentl syndrome, a real phenomenon in amyotrophic lateral sclerosis (ALS)?

<i>Introduction:</i> ALS, a neurodegenerative disorder, exhibits variable incidence and prevalence across various databases consulted. Among these, PRO-ACT stands out as the most extensive publicly accessible repository of aggregated ALS clinical trial information. The estimated male-female ratio is greater for men at younger ages, which tends to equalize with aging. If specific measures are not taken to address this, this higher male prevalence could result in a higher inclusion of men in clinical trials, which could lead to biases in the observed results, preventing the proper assessment of differences between sexes. Our aim was to describe the demographic dates of the population included in ALS clinical trials in the last 8 years at Spanish national reference centers, with special interest in female participation. <i>Methodology:</i> Retrospective and descriptive observational study using databases of national reference centers. <i>Results:</i> We analyzed the databases of 4 neurological Spanish reference centers during a period of 8 years. A total number of 426 subjects were included. A greater participation of the male sex was evident in all the studies evaluated, representing 64.55% of the subjects included. This predominance has not varied significantly over the last 8 years. Our results correlate with the data published in PRO-ACT to date, where men represent 60% of the total number of participants. <i>Conclusion:</i> The predominance of the male sex in ALS clinical trials is a consistent and invariable finding and is known as Yentl's syndrome. This phenomenon prevents the principle of neutrality of medicine, allowing for purely partial knowledge.