This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Memory impairment is most likely to occur in : 
Select and explain. 
A. Downs Syndrome, B. Alkaptonuria, C. Attention deficit disorder, D. Conduct disorder
A: Downs Syndrome
Answer: A: Downs Syndrome 
Explanation: Answer is A (Down's Syndrome) : "Patients with Downs syndrome (Trisomy 21) frequently develop lesions of Alzheimers disease in the third or fouh decade of life." Memory impairment forms an impoant characteristic of Alzheimer's disease and Down's syndrome thus may be considered as a predictor of memory impairment in later life