Possessing the knowledge concerning the likely causes of CRCD in other types of cancer, and taking into consideration that the etiological factors of cognitive changes in oncological treatment are IL-6, IL-10, BDNF, and TNF-α, it is logical to propose a hypothesis that a relationship exists between the advancement of a neoplastic process, the level of enumerated biological factors, and the level of cognitive functioning in patients with MM. The gene discussed is BDNF; the disease is Miyoshi myopathy.