A null mutation in Npy increased alcohol preference in mice,(28,29) and lower levels of Npy expression in discrete brain regions in P rats was associated with higher alcohol consumption.(30,31) Furthermore, there is an association between the decreased level of neuropeptide Y and increased anxiety in P rats,(33) and transfer of the P chromosome 4 QTL onto the NP background caused increased anxiety in NP.P rats compared with NP rats (unpublished data). Here, NPY is linked to Anxiety.