  We investigate the gravitational effects on the relativistic Dirac theory of
a system such as a Hydrogen atom in the braneworld scenario. A gravitational
dipole moment like contribution, arises in the nonrelativistic Hamiltonian of
the system through an exact Foldy-Wouthuysen transformation. This term violates
the equivalence principle for the weak interaction that is restored in the
average over the spins. Furthermore, it feels the effects of the extra
dimensions, so that in a Universe with two additional spatial dimensions its
energy contribution is amplified by an order of $\sim 10^{16}\ \text{eV}$
concerning to the energy of this term for ordinary space. The compactification
radius for a Universe with two extra dimensions is within the experimental
limits, where deviations from the inverse square law are being tested. This
suggests that the energy value for the gravitational dipole term in this
scenario may lead us to search for traces of extra dimensions in atomic
spectroscopy, as well as experimental constraints for these dimensions.
