Dec 8 (Reuters) - Data from small study of Biogen Alzheimer's drug:
* Show gradually increased doses of aducanumab associated with lower risk of brain swelling, compared with swelling seen in prior trials using fixed doses of the drug.
* Show experimental Alzheimer's drug signicantly reduces brain amyloid plaque, compared with placebo.
* Study involved patients with either mild or pre-symptomatic Alzheimer's
* Study shows that slowing of cognitive decline was similar to decline seen in earlier trials involving fixed drug doses
* Further company coverage: (Reporting by Ransdell Pierson)