Explore overlooked factors: investigate additional risk or protective factors, like genetic markers (e.g., apolipoprotein E, presenilin 1 and 2, and amyloid precursor protein), environmental toxins (e.g., lead, pesticides),93 mild traumatic brain injury,94 endocrine factors (such as hypothyroidism), sleep disturbance (like sleep apnea or chronic sleep deprivation),7, 95 bilingualism,96 vitamin and nutritional deficiencies,97 and the microbiome (e.g., gut microbiome).98 This evidence concerns the gene APOE and sleep apnea syndrome.