  Strong evidence for the presence of a warped Keplerian accretion disc in
NGC4258 (M 106) has been inferred from the kinematics of water masers detected
at sub-parsec scales. Assuming a power-law accretion disc and using constraints
on the disc parameters derived from observational data, we have analyzed the
relativistic Bardeen-Petterson effect driven by a Kerr black hole as the
potential physical mechanism responsible for the disc warping. We found that
the Bardeen-Petterson radius is comparable to or smaller than the inner radius
of the maser disc (independent of the allowed value for the black hole spin
parameter). Numerical simulations for a wide range of physical conditions have
shown that the evolution of a misaligned disc due to the Bardeen-Petterson
torques usually produces an inner flat disc and a warped transition region with
a smooth gradient in the tilt and twist angles. Since this structure is similar
to that seen in NGC 4258, we propose that the Bardeen-Petterson effect may be
responsible for the disc warping in this galaxy. We estimated the time-scale
necessary for the disc inside of the Bardeen-Petterson radius to align with the
black hole's equator, as a function of the black hole spin. Our results show
that the Bardeen-Petterson effect can align the disc within a few billion years
in the case of NGC 4258. Finally, we show that if the observed curvature of the
outer anomalous arms in the galactic disc of NGC 4258 is associated with the
precession of its radio jet/counterjet, then the Bardeen-Petterson effect can
provide the required precession period.
