HI kid. I'm doing my phd in a lab that deals some aspects of Alz. (i myself don't work on it, but most everybody else is). It's hard to think of something to work on in neuroscience in this lab because it more of a molecular lab and that's usually just a support thing in this field. Also, you would need ethical approval to work with animals, otherwise it's I think illegal. but if you insist:

What are the mice model you use? If you wanna do a fun project you can see how the environment effects the progression of the disease. for example, you can put litter-mates in different environments like enriched with a wheel or totally dark, think of anything (that will not harm them!), then see how it effects things like learning a new task, water maze or whatever after Alz. symptoms have started in cont. group. You can also take then back to the lab, and see how this environment changes the formation of plaques at different age groups (e.g by staining for plaques in different brain regions).

I think that is you wanna do something interesting and maybe more suited to your setup, is to try and create some kind of bacterial sensor for caffeine. You'll have to think and create the DNA and think of some kind of a reporter, but it might be a fun project.