Alzheimer’s Disease Nicotine’s relationship and contribution to dementia



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Alzheimer’s Disease


Characteristics of Alzheimer’s







Two major theories on the cause of Alzheimer’s disease

  • The Amyloid Cascade Theory:

  • Neruodegenerative process is triggered by the abnormal accumulation of amyloid plaques.









Role of Nicotine in Acetylcholine

  • Nicotinic receptors bind to acetylcholine.

  • Improve cognitive performance.

  • Prevent death of brain cells.

  • Delay cognitive decline in Alzheimer’s disease.



Other Neurotransmitters Systems

  • Nicotine increases dopamine release, a neurotransmitter critical in the proper functioning of the prefrontal cortex.

  • In Alzheimer’s, the dopamine system is affected, decreasing levels of the neurotransmitter in the cortex and in the hippocampus.



  • Dopamine agonists promote spatial working memory performance.

  • Studies show that only very small doses of the agents can achieve these improvements.

  • Excessive dopamine stimulation has been found to be harmful to prefrontal cortex function.



Nicotine also promotes the release of other neurotransmitters: norepinephrine and seratonin

  • Norepinephrine, as well as dopamine, has a vital influence on prefrontal cortex cognitive functioning. There is a 60% loss of norepinephrine neurons in aged primates and humans, and this loss is significantly increased in Alzheimer’s disease.

  • Some seratonin agonists are important in cognitive enhancement. They are used to manipulate other neurotransmitters systems such as acetylcholine, dopamine, and norepinephrine to alleviate behavioral and psychological symptoms in dementia.



Galanthamine

  • A water-insoluble alkaloid used to treat nervous system disorders.

  • Cognitive test scores of patients taking galanthamine improved.

  • Galanthamine has been found to improve memory by inhibiting an enzyme that breaks down acetylcholine and acts on the brain’s nicotinic receptors.



Conclusion

  • There is evidence showing improvement in cognitive performance in patients with Down’s syndrome and Parkinson’s disease when administered nicotine.

  • Studies state that nicotine can improve performance on a variety of tasks including learning, memory, and cognitive functioning.

  • Clinical observations show that long-term use of nicotine (i.e., smoking) is negatively correlated with risk for Alzheimer’s disease.



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