My grandfather was a bagpiper for his whole life, and in his last years, he suffered from Alzheimer’s disease. He could not remember any of our family members, what year it was, or where he was; yet, if he heard so much as the start of a bagpipe tune, he would sing the rest of the notes from memory, and even perform the instrument fingerings to go along with it. It could have been a song he learned for the opening of the Canso Causeway in 1955, and he could remember it effortlessly. My grandfather’s ability to remember music from years ago but not what he ate for lunch that day had always amazed me. Jacobsen et al. (2015) have found a possible reason for why the musical memory of patients with Alzheimer’s disease is mostly spared from decay, unlike the rest of the memory. The researchers believe that musical memory is separate from other memory systems; it has been shown that musical memory can be damaged while other memory systems stay intact, and the opposite has also been seen.

It is known that different types of musical memory use different brain regions. In Alzheimer’s patients, it is long-term musical memory that is the strongest. The researchers wanted to determine what brain regions play a role in long-term musical memory, and then determine how, if at all, these specific areas are affected by Alzheimer’s. So, they looked at functional magnetic resonance imaging (fMRI) scans of 32 young, healthy people while they heard music that was unknown, recently known, and long-known, to determine which brain regions were associated with the different types of musical memory, and to specifically locate which brain areas were linked with long-term musical memory. fMRI monitors brain activity by measuring changes in blood flow to different brain regions; brain cells consume energy as they fire, and they require additional energy to continue firing, which is brought to the cells by blood. Therefore, increased blood flow to particular brain regions indicates that those regions are active during the specific activity. The researchers found two brain areas that were linked to precise recognition of long-known music: the caudal anterior cingulate gyrus and the ventral pre-supplementary motor area (ventral pre-SMA). The caudal anterior cingulate gyrus is thought to be associated with prediction, expectation, and evaluation of events, and with decision making. It has been suggested that ventral pre-SMA is involved in sequence learning and planning.

Three indications of Alzheimer’s disease in the brain are accumulations of amyloid-beta (a sticky substance that causes plaques and tangles in the brain), reduced glucose metabolism (less energy consumption and therefore, less activity) in brain cells, and cortical atrophy (loss of grey matter/brain mass). The researchers looked at voxel-wise maps that showed the levels of these markers in different brain regions in 20 Alzheimer’s patients and 34 people without the disease. In comparison to the rest of their brain areas, the Alzheimer’s patients had less atrophy and less reduced glucose metabolism in the caudal anterior cingulate gyrus and the ventral pre-supplementary motor area. However, accumulation of amyloid-beta was found in both of these regions. The common pattern of development of Alzheimer’s markers in the brain is amyloid-beta accumulation, then reduced glucose metabolism, then cortical atrophy. The amyloid-beta found in the brain regions associated with long-term musical memory may indicate the beginning of the development of Alzheimer’s markers in these areas.

With that being said, in comparison to the rest of the brain, the areas that the researchers identified as important for long-term musical memory were relatively spared by Alzheimer’s disease. This could be an explanation for why Alzheimer’s allowed my grandfather to remember bagpipe music from his youth, but not much more recent events.

Source: Jacobsen, J. H., Stelzer, J., Fritz, T. H., Chételat, G., La Joie, R., Turner, R. (2015). Why musical memory can be preserved in advanced Alzheimer’s disease. Brain: A Journal of Neurology, 138, 2438-2450.