The present disclosure relates to compositions, formulations, and associated methods for treating neurodegenerative diseases, wherein the compositions include an alpha-1
adrenergic agonist, such as midodrine, and an alpha-2A
adrenergic agonist, such as
dexmedetomidine. Upon administering to a human subject, the alpha-2A
adrenergic agonist crosses the subject's blood-brain barrier thereby acting upon the subject's
central nervous system, whereas the alpha-1
adrenergic agonist does not cross the subject's blood-brain barrier. The alpha-1
adrenergic agonist minimizes or eliminates the systemic vascular effects induced by the alpha-2A
adrenergic agonist that causes the negative cerebral autoregulatory response, thereby enabling the alpha-2A adrenergic agonist to increase glymphatic flow in the subject's brain.