Why do many people with Alzheimer’s Disease (AD) retain their ability to recall music?

This was the subject of a fascinating study by Jacobsen, Stelzer, FritZ, Chetelat, LaJoie and Turner. “Musical memory is considered to be partly independent from other memory systems” said the researchers. Musical memory is “surprisingly robust” in patients with Alzheimer’s and various types of dementia. But why? This is not readily understood. “This is the first neuroscientific study to provide an anatomic explanation for the persistence of musical memory,” says researcher Jörn-Henrik Jacobsen, scientist at the Max Planck Institute in Leipzig and the University of Amsterdam.

The researchers studied 32 healthy human subjects and 20 with AD and 34 controls, and looked for the regions of the brain that encode long-term musical memory. They then looked at essential AD biomarkers and found “the regions identified to encode musical memory corresponded to areas that showed minimal cortical atrophy and minimal disruption of glucose-metabolism as compared to the rest of the brain.”

Researchers say the brain area that had been identified in long-term musical memory loses fewer neurons over time than the rest of the brain does. In addition, metabolism declines in this area not nearly as much. Even though the presence of amyloid deposits is similar in other areas of the brains studied but doesn’t appear to lead to the deficiencies associated with advanced stages of the AD. The brain areas responsible for long-term musical memory are therefore often affected least by loss of neurons and typical metabolic disorders in patients with AD.

The results of the study indicate that long-term musical memory is better preserved in Alzheimer patients than “short-term memory, autobiographical long-term memory and speech.” It can therefore remain largely intact even in advanced stages of the disease. “Our findings also lend support to a theory previously proposed in connection with other studies that found stronger network connections between the anterior gyrus cinguli and other nodes in patients with Alzheimer’s. This suggests that this area of the brain also provides specific compensatory functions as the disease progresses,” Jacobsen says, in explanation of the relevance and importance of the study’s findings.

The scientists hope further research will shed more light on the poorly understood mechanisms of long-term musical memory in patients with AD. “In the future, a sound understanding of the complex relationships could lead to a real therapeutic benefit of music in patient care,” Jacobsen believes.

Sources: http://dx.doi.org/10.1093/brain/awv135; http://www.mpg.de/9281090/alzheimers-long-term-musical-memory