<p><b>Notes</b>. MAS = Sydney Memory & Ageing Study; OATS = Older Australian Twins Study; HV = hippocampal volume;</p><p><sup>a</sup>Data presented for those with both HV & genetic data;</p><p><sup>b</sup>Data presented for those with Wave 1 & 2 HV & genetic data;</p><p><sup>c</sup>(Wave 2 -Wave1/Wave 1) *100;</p><p>NA = not available</p><p>Descriptive statistics for Sydney MAS and OATS participants with hippocampal volume and genotyping data available.</p