Antidepressants treat symptoms of depression. They can elevate mood, increase physical

activity and mental alertness, and improve appetite and sleep patterns. Many antidepressants

also are mild sedatives and treat mild forms of depression associated with anxiety.

The largest class of antidepressants increases the action of neurotransmitters by blocking

their removal (reuptake) from the synapses (spaces between nerve cells). These drugs

include tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors

(SSRIs). Other antidepressants are monoamine oxidase inhibitors (MAOIs), which

increase the length of time neurotransmitters work by blocking monoamine oxidase, an

enzyme that normally inactivates neurotransmitters.

Lithium is a drug that is used to stabilize the mood swings and unpredictable behavior

of people with bipolar disorder (manic-depressive illness).

Anti-Alzheimer drugs, used to treat symptoms of Alzheimer disease, act by aiding brain

neurotransmitters (acetylcholine) or shielding brain cells from glutamate, a neurotransmitter

that at high levels contributes to death of brain cells. 

Here lists examples of antidepressants and anti-Alzheimer drugs, such as duloxetine (Cymbalta) for antidepressants, donepezil (Aricept) for Anti-Alzheimer.