BOSTON ( TheStreet) -- Scientists are making great strides toward developing new tests enabling the early diagnosis of Alzheimer's disease, perhaps even before patients start exhibiting the loss of memory and cognitive function that are the terrible hallmarks of the neuro-degenerative disease. Coming up with drugs to effectively treat or even reverse Alzheimer's is proving to be much a more elusive goal, unfortunately. Tuesday's announcement by Eli Lilly ( LLY) that Alzheimer's patients treated with its experimental drug semagacestat were performing worse than placebo patients in two late-stage studies. (forcing Lilly to stop the studies) was just the latest in a string of negative results from Alzheimer's drug trials. Other recent Alzheimer's late-stage drug study failures have tripped up the partnership between Pfizer ( PFE) and Medivation ( MDVN), Myriad Genetics ( MYGN) and the now-defunct Neurochem. A drug owned by Elan ( ELN) and Wyeth (since bought by Johnson& Johnson ( JNJ)) and another controlled by Elan and Transition Therapeutics ( TTHI) are being studied in ongoing phase III studies despite what might be optimistically called mixed phase II results. Long term, recently announced breakthroughs involving new brain imaging techniques and the discovery of biomarkers for Alzheimer's might allow scientists to learn more about the causes of Alzheimer's. Along with new diagnostics, the scientific consensus seems to be moving towards designing clinical trials that target patients in early-stage Alzheimer's patients, or even patients with pre-Alzheimer's, which may give drugs a better chance for success. Meantime, drug companies forge ahead with Alzheimer's clinical trials. Perhaps one of the drugs listed below will succeed where so many others have failed. After Tuesday's bad news from Lilly, investors seeking Alzheimer's gold could use some cheering up. Ten Alzheimer's Disease Drugs in Mid- to Late-Stage Clinical Trials:Pfizer and Medivation Drug: Dimebon Drug type: Mitochondrial Stage: Phase III Dimebon failed a phase III monotherapy study that enrolled patients with mild to moderate Alzheimer's. An additional phase III study is still in progress: The "Concert" trial is studying the combination of Dimebon plus Aricept in patients with mild to moderate Alzheimers. Results are expected in 2012. Pfizer and Medivation are also conducting a phase III study of Dimebon in Huntington's disease, with results expected in the first half of 2011. Johnson & Johnson (with minority partners Pfizer and Elan) Drug: bapineuzumab Drug type: Amyloid beta Stage: Phase III Lackluster data released in 2009 from a closely watched phase II study has cast a long shadow over bapineuzumab's development. Most recently, Johnson & Johnson said top-line results from pivotal, phase III studies in mild to moderate Alzheimer's patients wouldn't be ready until the end of 2012, a pushback from 2011.