When follow-up was initiated 6 mo after baseline, the SIRs for BRCA1 carriers were similar for GS ≤ 6 (SIR 2.26, 95% CI 0.86–5.91) and GS ≥ 7 PCa (SIR 1.90, 95% CI 0.93–3.85), in contrast to the main results. Here, BRCA1 is linked to posterior cortical atrophy.