I didn't group these drugs together because they are old people diseases.  Hardly.  Mouse's father was hit hard with Alzheimer's in his mid-50s.  And many people in the US knows about Michael J. Fox and his battle with Parkinson's.  No, I lumped them together because the meds are used off-label as antidepressants and/or to deal with the side effects of anticonvulsants and antipsychotics.  So those of us dealing with bipolar disorder, epilepsy, schizophrenia, clinical depression, other affective mood disorders or whatever else antidepressants, anticonvulsants and/or antipsychotics are used for may require an anti-Alzheimer's or anti-Parkinson's med to either deal with our illnesses or ward off the side effects of the meds we're already taking.  I've tried Exelon (rivastigmaine tartrate) in the past and didn't get all that much bang for the buck.  I'm now evaluating Reminyl (galantamine HBr).  Mouse has tried Exelon (rivastigmaine tartrate) and Aricept (donepezil).  She's also evaluating Reminyl (galantamine HBr) as well as Requip (ropinirole hydrochloride).

The Parkinson's meds tend to work on dopamine, one way or another.  There are variations from med to med on exactly how they work on which receptors, and whatever neurotransmitters may be involved.  But some kind of dopamine action is the main attraction.  In the US there are only two dopaminergic meds available as official antidepressants, Wellbutrin (bupropion) and, if you take enough of it and get lucky, Effexor (venlafaxine).  If dopamine is the answer for you, or part of the answer, and neither of those meds work for whatever reason, you and your doctor should be exploring the Parkinson's meds.  The Parkinson's meds are also the first line of meds for serious cases of restless leg / periodic limb movement syndrome.

The Alzheimer's meds work in ways that are completely new to me.  I'll have to get back to you on them.  Hell, I'm taking one now, so you can bet I'll figure it out soon enough.

Another reason for grouping these meds together is that they have common effects that people like for some reason:

	They tend to make you lose weight.
	They tend to make you horny.
	They tend to improve your memory.
	They are effective antidepressants.

While those first two items are the last thing I need more of, I'll risk it  for the last two.  I've needed more Topamax (topiramate) and Neurontin (gabapentin) in my cocktail, so I've been much more of an idjit on psychiatric drugs.  And with all the crap in my life of late I've been pretty damned depressed.  While there really isn't much of a pharmacological answer to that depression, more a case where I just have to work out my freaking issues, I can use all the help I can get from an antidepressant.  I can accept sleeping 9-10 hours a night because of all the meds I take, but 12 hours a night and being tired most of the day like I was two years ago is, well, depressing.  

The Parkinson's meds are also good for dealing with some forms of Extrapyramidal Symptoms (EPS) you get from antipsychotics. See the antipsychotics pages for more information on EPS.  It's scary, but with the newer atypical antipsychotics EPS is usually something that can always be resolved one way or another that is not permanent.  Mine went away!  Conversely Seroquel (quetiapine) is catching a lot of buzz right now in treating many symptoms of Parkinson's because it is so effective in dealing with EPS symptoms, despite being an atypical antipsychotic.

Because they mess with dopamine it may not a good idea to mix Parkinson's meds with epilepsy.  But your neurologist always has the final say on anything like that.  I've just begun looking into how these meds work, so don't take what I write as Gospel!  However there doesn't seem to be an issue with the Alzheimer's meds and epilepsy.  Again, always have a long talk with your neurologist about mixing classes of meds.