With Alzheimer’s disease, acetylcholine levels are reduced
About Acetylcholine
Here is MY quick review that discusses the overall importance of acetylcholine (ACh) and its actions. References and researchers have written about ACh in many different ways but this summary was the only way I could make sense of it, bear with me:
For proper functioning, there must be a balance between two neurotransmitters, Dopamine (DA) and ACh. The reason for mentioning DA is because BOTH of these neurotransmitters contribute to the lack of movement and control (physically and behaviorally), as a result, many drugs try to target their receptors or pathways attempting to restore the imbalances. Mnemonic PDA = Parkinson’s Disease/Decrease of DA
But sometimes the damage of ACh & DA is unknown and treatment or medications are unfortunately only temporary (it doesn’t stop or reverse the progression). Therefore, these dysfunctions are only possible theories and other pathologies may have to be studied such as amyloid proteins and plaques (i.e. Alzheimer’s).
A decrease in DA equals a lack of controlled movements like with Parkinson’s Disease and a decrease in ACh such as Alzheimer’s also leads to a loss of memory and other functions. Glutamate is the most common neurotransmitter in the brain and is involved in learning and memory. As the brain cells of someone with Alzheimer’s Disease die, they release excess amounts of glutamate, causing cell toxicity or death.
GABA is inhibitory thus reducing the sensitivity of muscle cells and decreasing muscle movement. GABA is decreased with Parkinson’s disease, possibly contributing to symptoms such as tremors, tics, and bradykinesia. Targeting GABA sites has become more helpful in recent research in treating Alzheimer’s Disease.
The key to remembering ACh function is understanding how acetyl behaves excitingly. And when you are excited, you use your MUSCLES (cholin”ergic”, meaning to energize or stimulate) and everything else to show it! anticholinergic = slowing digestion (constipation), decreasing secretions and involuntary movements (dryness and more constipation)
A LACK of ACh and DA shows depressive symptoms, decrease expressions, and purposeful movement. In other words, Ach equals ACTion.
DA medications i.e. levodopa are used to treat PD and attempt to balance the ACh and restore DA, but PD is a progressive loss of DA, which leads to an imbalance of ACh. The other loss of ACh is with Alzheimer’s, in which the body attacks certain cells that produce ACh. These are 2 different mechanisms, among other possible factors that could lead to a loss or imbalance of ACh.
In Conclusion
Overall, without ACh, there is a loss of MOTOR function, memory/cognition, or paralysis but too much ACh can cause problems like seizures, which is why GABA is important or how the brain makes sure it does not get TOO exciting.
Balance is key and specifically with ACh, too much or too little will show a lack of MOTOR control, which can affect everything in the body. The purpose of discussing DA is to tie everything together and also explain why treatment and medications are very difficult and challenging.
DA and ACh are supposed to have a reciprocal relationship, but losing ACh does not mean DA is also decreasing (as with Parkinson’s) or increasing… and the mechanisms are primarily unknown. Also, note that psychiatric medications specifically target DA receptors, which can also affect ACh/movement/mood.
That’s the gist of ACh! Thanks for reading and hopefully it’s more clear 🙂
Other Considerations of Acetylcholine
ACh can also be inhibitory like with nerve gas such as sarin that’s used in warfare, as well as organophosphate insecticides such as parathion, that achieve their effects through the inhibition of acetylcholinesterase, thereby allowing acetylcholine to remain active and in contact with its receptor. Antidotes such as atropine are used to block acetylcholine receptors, thereby nullifying the effects of excessive acetylcholine.
ACh is the neurotransmitter used at the neuromuscular junction—in other words, it is the chemical that motor neurons of the nervous system release in order to activate muscles. This property means that drugs that affect cholinergic systems can have very dangerous effects ranging from paralysis to convulsions.
Inside the brain, ACh functions also as a neuro-modulator—a chemical that alters the way other brain structures process information rather than a chemical used to transmit information from point to point.
ACh is also a neurotransmitter outside the brain or in the autonomic nervous system, both as an internal transmitter for the sympathetic nervous system and as the final product released by the parasympathetic nervous system.
–Wiki
ACh is the first neurotransmitter to be discovered. It plays a major role in the peripheral nervous system, where it is released by motor neurons and neurons of the autonomic nervous system. It also plays an important role in the central nervous system in maintaining cognitive function. Damage to the cholinergic neurons of the CNS is associated with Alzheimer’s disease.
