Abstract: This invention proposes that the best therapeutic strategy for treating and/or preventing Alzheimer's disease (AD), age related macular degeneration (AMD) and other diseases that exhibit extra-cellular debris deposits, such as atherosclerosis, is the inhibition of the complement pathway. A model for the accumulation of extra-cellular debris through the activation of the complement pathway is presented, and the primary pathogenic role of the debris in the etiology of the disorders is explained. Previously identified complement inhibitors are identified as therapeutic agents for the treatment and/or prevention of AD, AMD and other diseases that exhibit extra-cellular debris deposits.