The FDA put Elan’s experimental Alzheimer’s medication ELND005 on the approval fast track. The company announced the expedited status Wednesday in a statement with its partner, Toronto-based Transition Therapeutics, from whom Elan licensed the therapy.

Just as Otsuka and Lundbeck are going beyond tau tangles and plaques, Elan is approaching the brain-degeneration disease from a different angle. Elan’s experimental drug focuses on agitation and aggression that is found among moderate-to-severe Alzheimer’s disease patients. The companies said in a statement that ELND005 Phase II results “appeared to decrease the emergence and severity,” of aggression and agitation. The companies said that around 60% of AD patients develop agitation and aggression. The Otsuka/Lundbeck effort, which is gearing up for Phase III testing, focuses on cognitive function among moderate Alzheimer’s patients.

Elan’s focus on later-stage patients may be considered a retroactive pursuit, in light of recent discussions that  arresting the disease may be effective before it takes hold, but a need for downstream treatments remain critical. Non-profit advocacy group the Alzheimer’s Association says that one-third of seniors will die of Alzheimer’s or another form of dementia. The group also notes that Alzheimer’s-related deaths rose 68% between 2000 and 2010, and the number of AD patients is only expected to increase.

Among those pursuing late-stage treatments are Eli Lilly, which is reframing its experimental drug solanezumab as a possible treatment for mild Alzheimer’s disease patients. The drug failed among its initial target—moderate patients—but that there was a positive read among a small subset of patients. Its newest round of trials will focus on mild patients, and recruitment will be limited to patients who test positive for beta-amyloid, which is thought to be a possible trigger for Alzheimer’s disease.

Eli Lilly, for example, is repositioning its experimental drug solanezumab further upstream. The drug failed among later stage patients, but the company found a possible positive result if it pooled data from a subset patient group and pooled data from two trials. The company’s new effort will focus on this subset—mild patients. The company is also requiring candidates to test positive for beta amyloid to enter the trial.

Merck is also following the beta-amyloid lead, and announced Sunday that its Phase Ib BACE inhibitor showed progress among mild-to-moderate AD patients. The company released its data at the Boston Alzheimer’s Association International Conference and said it was expanding its research into Phase II tests, which will include up to 1,700 patients. BACE inhibitors act on precursor proteins which lead to amyloid plaques. The inhibitors seek to block this action, and drug makers including Roche and AstraZeneca are among those pursuing this approach. Lilly abandoned its Phase II BACE inhibitor last month over liver abnormalities among clinical trial patients. The company said it did not think the liver abnormalities were linked to the BACE inhibitor.