Introduction: Cognitive functions contains the processing of thoughts, memory, and attention. Deficiency in one or all of the abovementioned functions may cause behavioral changes that commonly is known as cognitive disorders. The most common cognitive disorders are Alzheimer's disease and Parkinson's disease. These diseases, in addition to the destruction of cognitive behavior (memory, learning and attention) are associated with disability of movement, a common symptom of cognitive impairment. These diseases are accompanied by many histological alterations, such as extracellular amyloid-β (Aβ) peptide-containing plaques, tau protein, astrocytic gliosis, and reactive micoglia. This histological changes are linked with the abnormalities of the receptors. The pathological effect in the structures and functions of neural receptors leads to dysregulation of intracellular pathways and cellular signals. Conclusion: The intracellular signaling cascade regulated calcium ion flux, membrane excitability, and activation of various receptors. Neurotransmitters play an important role in facilitating the processes of learning and memory. Impairment of these receptors may cause cognitive changes.