What are the common diseases associated with acetylcholine deficiency?

The common diseases associated with acetylcholine deficiency include myasthenia gravis, Lambert-Eaton myasthenic syndrome, Alzheimer's disease, and Parkinson’s disease.

1. Myasthenia gravis is an autoimmune disorder characterized by muscle weakness, particularly after periods of activity. In this condition, the immune system mistakenly targets and inhibits or destroys acetylcholine receptors. Consequently, muscles fail to receive the necessary neurotransmitter, disrupting their normal function. The absence of acetylcholine results in an inability of muscles to contract effectively, leading to muscle weakness and fatigue. 
2. Alzheimer's disease is the leading cause of dementia in older adults; it manifests through symptoms such as profound memory loss and cognitive difficulties that significantly disrupt daily functioning. In Alzheimer's disease, individuals often exhibit reduced levels of acetylcholine; the condition damages the cells responsible for both producing and utilizing acetylcholine. 
3. Parkinson's disease is a progressive neurological disorder characterized by tremors, involuntary movements, and challenges related to mood and cognition. Researchers have found that individuals with Parkinson's disease frequently experience a reduction in dopamine levels, allowing acetylcholine to become more prominent. This shift leads to an excessive excitation of muscles, resulting in symptoms like jerking movements and tremors. 
4. Lambert-Eaton myasthenic syndrome (LEMS) is a rare condition affecting the neuromuscular junction, specifically disrupting the release of acetylcholine. This disorder presents distinct clinical features, including weakness in proximal muscles and diminished tendon reflexes.