The present disclosure relates to a series of substituted N-heteroaryl tetrahydro-isoquinoline derivatives of formula (I). wherein R, R1, R2, X, m, n and p are as described herein. More specifically, the compounds of this invention are modulators of H3 receptors and are, therefore, useful as pharmaceutical agents, especially in the treatment and/or prevention of a variety of diseases modulated by H3 receptors including diseases associated with the central nervous system. Additionally, this disclosure also relates to methods of preparation of substituted N-heteroaryl tetrahydro-isoquinoline derivatives of formula (I) and intermediates therefor.