Neurotransmitters are basically chemical messengers your neurons (or nerve cells) use to communicate with one another. When one neuron wants to communicate to another, it releases this chemical into the synapse (the space between neurons), and the chemical finds its way over to little receiving units on the other neuron (called neuroreceptors), and binds to them, thus completing the transmission. Some types of neurotransmitters are then ‘recycled’ into the sending neuron, which is a process called reuptake. This prevents the neurotransmitter from continuiing to send the same message, as well as (from what I understand) making them available again to be transmitted as a new signal when needed.
Sometimes the messages aren’t received by the receiving neuron, and the message is simply ‘lost’ so to speak. This is at least how the information on the ‘chemical imbalance’ of Depression seems to work – the serotonin neurotransmitter is reabsorbed before it binds to the receiving neuron, and thus the communication is never completed.
Many antidepressant and anti-anxiety medications work by blocking the reuptake of certain neurotransmitters (reuptake inhibitors). By blocking this reuptake, the medication winds up leaving the neurotransmitters in the synapse longer, which can increase or prolong the effect of that neurotransmitter’s “message”, and also ‘fix’ those broken messages that are lost in Depressive patients – by giving those neurotransmitters more time and more chances to be received.
There are also other types of medications that affect neurotransmitters in different ways. For example, one type of medication can block neurotransmitters from binding with the receiving neuron, thereby preventing messages from being sent. Also, there’s medications that will ‘activate’ neuroreceptors, basically sending messages that weren’t actually meant to be sent by the body.
One more curious thing (at least to me) to note: neurotransmitters are considered a specific type of hormone; that is, these hormones are specifically involved in neuron communication only.
Anyway, here are the main neurotransmitters that are linked to depression and anxiety, and a rundown of what they are linked to and what medications act upon them: (note: there are a number of other neurotransmitters besides these ones, but I’m not aware of any others linked to anxiety & depression, so I’m focusing solely on the relevant ones)
Neurotransmitters linked to Anxiety & Depression:
GABA (gamma-aminobutyric acid)
This neurotransmitter has an inhibitor effect on the nervous system – it slows down transmission of nerve impulses, relaxes muscles, and so forth.
Medications which work on this:
Benzodiazepines work by somehow activating GABA receptors, causing the relaxing sedative effect.
Dopamine
This neurotransmitter is most commonly known for its relationship to feelings of ‘pleasure’ or ‘desire’, but is also involved in body movement, memory, attention, and so on
Medications which work on this:
some multiple-reuptake inhibitors block this chemical from reuptake The SAM-e supplement reportedly increases levels of dopamine & improves ‘binding’ to the receptors *interesting note: cocaine actually blocks reuptake of this neurotransmitter as well
Epinephrine (adrenaline)
This neurotransmitter increases heart rate & blood pressure
Medications which work on this:
Beta Blockers can block this neurotransmitter at ‘beta-adrenergic receptors’ in the body, which prevents the communication of the message. This can have the affect of lowering heartrate and blood pressure and producing ‘calming’ affects
Norepinephrine
This neurotransmitter is very similar to epinephrine – it increases heartrate, blood pressure, raises blood sugar levels, etc
Medications which work on this:
SNRI medications and some multiple reuptake inhibitors block this from reuptake also Beta Blockers can block this neurotransmitter at ‘beta-adrenergic receptors’ in the body, which can have the affect of lowering heartrate and blood pressure and producing ‘calming’ affects
Serotonin
This neurotransmitter has been linked to mood/emotion, anxiety, behavior, learning, sleep, sexuality, appetite etc
Medications which work on this:
SSRI medications & some multiple reuptake inhibitors block this from reuptake The SAM-e supplement reportedly increases levels of serotonin & improves ‘binding’ to the receptors Also, the supplement 5-HTP, a precursor to serotonin, can increase serotonin levels in the body.