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I guess I jumped the gun and gave the answer away in my title, but\u2026 does the loss of memory due to diseases like Alzheimer\u2019s affect memory for music?<\/p>\n
Typically in research fields, losing\u00a0something allows us to understand how that something works. In this case, losing memory as a result of Alzheimer\u2019s disease provides information on what is cognitively impaired as well as what is\u00a0not<\/em>\u00a0impaired. So does losing your memory due to dementia impair memory for music? \u00a0If evidence points to the answer no, perhaps there exists a unique memory system solely for music; but if evidence points to the answer yes, perhaps there still exists a unique memory system for music. That\u2019s pretty confusing. I\u2019ll make a valiant effort to explain what I mean by analyzing a psychological study. Kerer et al. (2013) seek to answer this main research question by examining explicit memory for music in individuals with and without cognitive impairment, including those with Alzheimer\u2019s disease.<\/p>\n <\/p>\n <\/p>\n Memory is a complex system \u2013 including but certainly not limited to \u2013 neurons, electrical and chemical signals, proteins, and many different storage systems. To scratch the surface, explicit memory is basically the conscious search to recall prior experiences, events, facts, or information. To be clear, the following study measured explicit memory as opposed to implicit memory, which is the involuntary and unconscious memory system. (For example, stating what you ate at your last meal relies on your episodic memory; whereas knowing how to walk is typically an implicit memory.) The Kerer et al. study involved individuals with dementia, characterized by the deterioration of cognitive functions \u2013 memory, language, attention \u2013 which leads to impairment in the performance of daily activities. Other individuals had mild cognitive impairment (MCI), which is the transitional state between normal cognition and development of dementia. A previous blog post<\/a> also describes the use of music for individuals with dementia.<\/p>\n The purpose of the present study was to examine music memory by testing individuals with different stages of dementia in their cognitive ability to identify familiar music excerpts. In other words, is there any part of explicit memory for music that remains intact despite having dementia?<\/p>\n The study included 10 individuals with Alzheimer\u2019s disease (AD), 10 MCI individuals, and 23 healthy (control) individuals. Everyone took the MMSE (mini-mental state examination) to assess mental status, covering five areas of cognitive function: orientation, registration, attention, recall, and language (Kurlowicz & Wallace, 1975). For reference, lower MMSE scores are correlated with higher cognitive impairment. As for experiment measures, the researchers created a test with 24 highly familiar music excerpts. Before this experiment, the researchers created a pilot study to make sure the songs were indeed familiar; the chosen songs ended up mostly being childhood and folk tunes. The reason why the researchers chose songs that were familiar was because, granted you\u2019ve heard the song before, whether you recognize the tune depends on your episodic memory. So when most Americans without memory impairments hear a song like \u201cthe itsy bitsy spider,\u201d the episodic memory is ignited, and they think, \u201coh boy, this takes me back to the good ol\u2019 days,\u201d or something analogous to that statement.<\/p>\n OK so now let\u2019s pretend you\u2019re taking the experiment. You walk into a room, go through initial screening process like signing consent forms and filling out other papers, then you\u2019re instructed to put on headphones. You get randomly assigned to listen to a bunch of songs \u2013 some originally vocal, others originally instrumental, but all made into piano renditions. Also, you may hear some songs that are distorted, as in the pitches of the notes are changed to make it sound different from how you originally remember hearing the song.<\/p>\n After every excerpt, you\u2019re asked to name the song. If you\u2019re thinking, \u201cuh oh. I feel like I\u2019ve heard this song before, but I can\u2019t remember the exact name,\u201d then the researchers give the option of letting you choose the correct song name from multiple choices. If you\u2019re still thinking, \u201cuh oh. I\u2019m drawing a complete blank on the name of the song,\u201d and can\u2019t choose between the multiple choices, then the researchers give yet another option to let you briefly write down any familiar aspects of the song\u2026 where you\u2019ve heard it, what you associate with it, etc. These series of tasks measure your verbal explicit memory for music, as in your ability to search your brain for a particular sliver of information, and verbally spit it out.<\/p>\n Next you\u2019re asked whether the original melody is altered (are the pitches different from the original tune?), and then whether you remember the original version of the song being instrumental or vocal. These last two questions measure nonverbal explicit memory for music, or your ability to discern the quality of music based on your memory for it.<\/p>\n Now that we\u2019ve covered the procedure of the study, statistical tests were used to analyze the data. Data revealed that healthy individuals performed better on the naming task than did individuals with MCI and AD. Aka healthy participants would be more correct in naming the childhood song \u201cMary had a little lamb\u201d than would the affected participants. Data also showed that a higher MMSE score correlated to better performance on the naming task. Surprisingly, the clinical groups performed better<\/em> on the music quality tasks than did the control group! Individuals with MCI and AD were more accurate to say something along the lines of: \u201cI remember this song being an instrumental tune,\u201d (differentiating between quality of the song) as well as \u201cThis version of the song that I\u2019m listening to for this experiment sounds different from how I remember it\u201d (detecting pitch distortion). Thus, a lower MMSE score correlated with a better performance in these two tasks. To wrap this all up, the study revealed that the control group performed better in music tasks requiring verbal memory, whereas the clinical groups performed better in nonverbal discrimination tasks.<\/p>\n So are musical recognition and music memory spared in individuals with dementia? Yes and no. It seems that \u2013 parallel to what we\u2019ve discussed in class with amnesiac individuals \u2013 episodic and verbal explicit memory are impaired in AD individuals. However, nonverbal explicit memory, which in this case is the ability to discern the quality of sound, remains intact. This means that we have a specialized memory system for music independent of verbal and visual memory, but, going back to the \u201cpretty confusing\u201d bit earlier in the post, not all <\/em>music memory is equal. The present study shows that we may have separate memory systems for music within explicit memory: nonverbal and verbal systems, or one distinct mechanism for identification and another for discrimination of music. Hopefully not so confusing anymore.<\/p>\n Going off on a related, but undeniable tangent, I\u2019m currently taking a neurobiology course. A couple of weeks ago we watched a video<\/a> of a man diagnosed with both anterograde and retrograde amnesia. The gentleman could not remember anything after about 10 seconds, indicating an intact short-term memory but the loss of long-term memory. Additionally, he could not remember anything from his past except for recognizing his wife. Despite the near complete loss of memory, he remained a proficient pianist (music was his profession before his amnesia). This unscathed memory for music is fascinating because it provides further evidence that music has a unique storage system in our brains; or at least that the sensorimotor and nonverbal aspects of the brain that are linked to music remains intact.<\/p>\n Back to the current study. As for why the clinical groups actually performed better and not just equally as well as the healthy subjects for the nonverbal musical memory tasks, attention is a possible explanation. Perhaps the healthy subjects directed more of their attention on naming the music excerpt, leaving less attention available to detect distortion of the pitches and judgment of timbre. This makes sense, as we learned in class that the capacity of attention is limited, especially when attending to multiple tasks that require the same sensory system. In this case, participants were asked to perform two tasks, identifying and discriminating, involving the auditory system. Furthermore, since the clinical groups did not have the information available to identify the music, they focused their full attention on the differentiating task, leading to better performance.<\/p>\n There are countless opportunities to utilize music in medical institutions and research knowing that memory for music can be spared even in individuals with Alzheimer\u2019s disease. Some ideas include: using music to relax patients struggling with anxiety or trauma, music to probe memory systems and facilitate remembering, and rehabilitation of motor skills using music. \u00a0This website<\/a>\u00a0offers more information on music therapy and neurology.<\/p>\n This is a neat blog post<\/a> on the use of music after post-op recovery.<\/p>\n