1. Alzheimer's disease  (Trust Mark: Doctor-Reviewed)
Alzheimer's disease (AD), one form of dementia, is a progressive, degenerative brain disease. It affects memory, thinking, and behavior. Memory impairment is a necessary feature for the diagnosis of this or any type of dementia. Change in one of t...• Reviewer: Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

2. Organic brain syndrome  (Trust Mark: Doctor-Reviewed)
Organic brain syndrome (OBS) is a general term that refers to diseases (usually not psychiatric disorders) that cause decreased mental function.• Reviewer: Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.