We investigate whether the annual modulation observed in the DAMA experimen
t can be due to a weakly-interacting massive particle (WIMP) with an axial-
vector (spin-dependent; SD) coupling to nuclei. We evaluate the SD WIMP-pro
ton cross section under the assumption that such scattering accounts for th
e DAMA modulation, and we do the same for a SD WIMP-neutron cross section.
We show that SD WIMP-proton scattering is ruled out in a model-independent
fashion by null searches for energetic neutrinos from WIMP annihilation in
the Sun, and that SD WIMP-neutron scattering is ruled out for WIMP masses g
reater than or similar to 20 GeV by the null result with the DAMA Xe detect
or. A SD WIMP with mass less than or similar to 20 GeV is still compatible,
but only if the SD WIMP-neutron interaction is four orders of magnitude gr
eater than the WIMP-proton interaction.