What can be the effect of taking all these drugs at once?

The Ativan is a benzo, 2mg is considered equivalent to 20mg diazepam (Valium). Benzo effects may include: memory impairment, oversedation/confusion, depression, emotional blunting… they may be enhanced in the elderly. Paradoxical adverse effects might include hostility, rage, irritability.

Remeron (mirtazapine) has two main effects – sedation and weight gain. Paradoxical effects include hostility and aggression.

The Ativan + the Remeron "may produce additive effects on the impairment of cognitive and motor skills."

Effexor at 75mg – wide possible profile, the patient medication leaflet will have the specific Black Box warnings (as will the Remeron’s), or you can read them at rxlist.com.

I don’t know about the 2 alzheimer’s medications, but there are drugs’ sheets available online for them, simple go to drugs.com, or rxlist.com (comprehensive info on the medications you list).

If the alzheimer’s medications came after the benzo/antidepressants, then, yes, the side-effects of the benzo/antidepressants could have produced a pseudo-alzheimers’ state – benzos alone can do this (ref. Ashton Manual, about 3/4 down the page) "Older people are more sensitive than younger people to the central nervous system depressant effects of benzodiazepines. Benzodiazepines can cause confusion, night wandering, amnesia, ataxia (loss of balance), hangover effects and "pseudodementia" (sometimes wrongly attributed to Alzheimer’s disease) in the elderly and should be avoided wherever possible. Increased sensitivity to benzodiazepines in older people is partly because they metabolise drugs less efficiently than younger people, so that drug effects last longer and drug accumulation readily occurs with regular use. However, even at the same blood concentration, the depressant effects of benzodiazepines are greater in the elderly, possibly because they have fewer brain cells and less reserve brain capacity than younger people." (Prof. Ashton)

You might find the detailed medication sheets at rxlist.com very helpful.

A face-to-face chat with a doctor should hopefully be able to help.

That is definitely not a question for yahoo. You should talk to your physician as soon as you can.

In simplistic terms (I don’t want to get all fancy):

Ativan is generally prescribed to lower anxiety, aggression, all that good stuff.

Effexor and Remeron are both anti-depressants.. both work in different ways.

Namenda and Aricept are actually Alzheimer’s drugs. There really isn’t that much to say about them.. Alzheimer’s is a tricky disease and no medications are beyond "minimally" effective.

I’m going to assume that this is all being given to someone with Alzheimer’s who shows signs of depression/withdrawal and also general anxiety, possibly aggression?

The major side effect from all of those put together is going to be drowsiness and yes, some disorientation. BUT if we’re talking about an Alzheimer’s patient here, the disease is going to make them far more disoriented and generally "out of it" than any combination of those medications will.

Be patient with your doctor. Alzheimer’s is considered a terminal disease and there is NO known cure. We don’t even understand how it works all that well. The best the doctor can really do is try different combinations of medications and see if they help manage some of the symptoms. Even then, the condition is degenerative.