During my dissertation work at Iowa I conducted a large-scale study of lesion patients in an attempt to identify any consistent patterns of lesion locations that were associated with musical anhedonia (musical anhedonia = a lack of enjoyment from music). The paper from this work was just published in Neuropsychologia.
Previous work has identified musical anhedonia in a small number of patients with focal brain damage (<5 such cases have been identified). I studied ~80 patients and did a series of questionnaires to see if any showed indications of musical anhedonia. These individuals had brain damage due to stroke, brain surgery, or other types of focal neurological damage (but not neurodegenerative disorders like Alzheimer's disease or more diffuse traumatic brain injury). What surprised me was that there were no real indications of musical anhedonia in this patient group, aside from one individual with damage to the right-hemisphere putamen/internal capsule. This part of the brain is involved in reward and motivation for other behaviors, so it is interesting that she showed a seemingly specific deficit for music.
These results seem to indicate that acquired musical anhedonia is quite rare in patient populations. After thinking on this for a while, it started to make sense to me. We know from anecdotal experiences and from research in music therapy that music is a very powerful therapeutic tool for individuals with even the most severe neurological disorders. Every time I give a talk somewhere, I have conversations with individuals that go something like: "My aunt had dementia and the best part of her day was when the musicians would come and sing with them." Part of its therapeutic usefulness may be the fact that it is quite hard to lose the capacity to enjoy music.
If you're interested, check out the paper in the link above or on my 'publications' page. I also chatted about musical anhedonia on LA NPR a few months ago; a link to that interview is on the 'press' page.