3.
http://www.nhs.uk/Conditions/downs-syndrome/Pages/complications.aspx
4.
http://www.alz.org/dementia/down-syndrome-alzheimers-symptoms.asp
5.
http://www.webmd.com/children/health-problems-related-to-down-syndrome
6.
https://www.nichd.nih.gov/health/topics/down/conditioninfo/Pages/faqs.aspx#adults