**1. Introduction**

The neurodegeneration is a common feature of different disorders, and many partners are involved in this mechanism. The last effect of degeneration is normally observed in the spine defects: reduction of spine density and alteration of morphology or functionality. The degeneration of neuron activity normally leads to the complete cell death.

The most neurodegenerative disorders are essentially affected by neurodegeneration of spine density and functionality, but the initial step or the trigger point is different from each other. Neurodevelopmental disorders or neurodegenerative disease related to the age affects patients in different ways but with the same effect. For this reason, a neurodegeneration is normally an intriguing topic for all scientific communities. Some of the molecular pathways involved in neurodegeneration associated to the most common neurodegenerative disorders are listed below.
