Scientists are people like the rest of us, and people have issues with change - even those working to create that change. So all fields of science have a certain inherent degree of dogma versus heresy; on the one hand, funding organizations want the best chance of placing resources where they will do the most good, and so support the consensus view. On the other hand, leaps in understanding come from challenges to the orthodoxy. A healthy field is rife and energetic with heresy - where many new and different ideas are tested by the scientific method. This Post-Gazette pieces gives a taste of how this all looks in Alzheimer's research: "For more than 20 years, the leading theory has held that sticky blobs in the brain called amyloid plaques cause Alzheimer's. Because that idea has numerous problems, doubters argued that the plaques might be innocent bystanders to the real, 'upstream' culprit. If so, targeting the plaques, or the rogue protein called beta-amyloid that forms them, would do nothing to help [those] who suffer from Alzheimer's."

Link: http://www.post-gazette.com/pg/06321/739244-115.stm