Cause-effect: music therapy and Alzheimer's Disease by ____

Effects on memory

robertkottke — 2024-04-12 20:44:06 UTC

Although AD patients seem to have issues recalling important autobiographical information (such as their address or their spouse's name), many maintain a strong ability to recognize melodies (21). In following with this, AD patients seem to maintain a capability for music-evoked autobiographical memory. Nostalgic or pleasant music seems to spark intense emotions as well as the retrieval of details that were formerly forgotten by the patient (21). This effect has also been observed in non-AD-affected individuals (21). Patients are observed to better memorize a sung phrase than a spoken phrase (5). Improved memory has generally been correlated with MT

Introduction

robertkottke — 2024-04-13 05:00:34 UTC

To navigate, start with an observed effect of music therapy on AD - they will be tinted red. From there, follow the arrows to find a hypothesized mechanism that may help explain this effect.

The anterior hippocampus

robertkottke — 2024-04-15 01:46:22 UTC

A somewhat recent meta-analysis of neuroimaging with respect to music identified the anterior hippocampus as one of the regions most likely to be activated in response to emotionally evocative music, solidifying its function as a processor of such stimuli (20). The anterior hippocampus also plays a strong role in autobiographical memory (21). That the two functions are localized within the same space may shed light on the inner workings of this phenomenon (21). At the same time, it should be noted that emotional responses to music and autobiographical memory also share spaces in other parts of the brain (21).

"The Mozart Effect"

robertkottke — 2024-04-15 18:55:43 UTC

In 1998, a study by Johnson et al. reported significant improvement in AD patients' spatio-temporal reasoning following a session of receptive music intervention to Mozart. For some period, it was believed that Mozart boosted cognitive abilities (5,23). This experiment was recently replicated and no significantly similar results were found. It is currently believed that the phenomenon is neuropsychiatric in nature, where improved mood from listening to Mozart boosts capabilities (5,23).

Music therapy and dopamine

robertkottke — 2024-04-15 19:04:46 UTC

Dopamine has been shown to regulate motor function and soften the effects of aging on the brain (21). Its availability is correlated with learning and memory capabilities (4). In fact, neural imaging analyses of older musician's brains show features of an unprecedentedly younger brain (21). Dopamine depletion is common in those affected by AD (21). Music therapy has been shown to induce dopamine release and availability in sensitive areas of the brain's reward system, including the nucleus accumbens and ventral striatum (21). In short, this theory suggests that by promoting the presence of dopamine, music therapy effectively rejuvenates the effects of age on the brain and counteracts AD lesions.

The ACC and SMA as preservers of music-related cognition

robertkottke — 2024-04-15 19:05:02 UTC

The encoding of familiar music (music one has known for some time) as well as the processing of music-evoked emotion both involve the caudal anterior cingulate cortex and the ventral pre-supplementary motor area (21). These are some of the final regions to become lesioned as AD progresses, which helps us understand why patients maintain capabilities with these functions despite issues in many similar areas of cognition (21).

Neuropsychiatric mechanisms

robertkottke — 2024-04-15 19:05:36 UTC

One of the more common - and more grounded - ideas attempting to explain these results is that improved emotional disposition leads to a stronger performance on tests for cognitive abilities (5). Studies have closely linked a reduction in anxiety to improved autobiographical memory, and another found that changes in the emotional makeup of songs affected performance, solidifying emotion as a significant factor (5).

Immune response relaxation

robertkottke — 2024-04-15 19:05:39 UTC

AD is partially understood as a product extended immune responses. Maladaptive inflammatory immune behaviors with roots in genetics and microglial priming have shown to be a significant contributing factor in AD (22). By reducing endocrine stress responses and relaxing immune activity, MT can promote the easing of brain inflammation and as a result improve cognitive function (21)

The neuroendocrine hypothesis

robertkottke — 2024-04-15 19:05:43 UTC

Articles have indicated that MT has altered hormone levels in patients such as cortisol, testosterone, and estrogen (5). They have also managed to link the decrease of fugue states in Alzheimer's patients to a rise in testosterone and 17-beta-estradiol - two hormones with other identified preventative effects in specific symptoms of AD (5,19). That music therapy promotes the secretion of these hormones bodes well for the effectiveness of the remedy.

Neurogenesis in an anterior hippocampal formation

robertkottke — 2024-04-15 19:05:47 UTC

Neurogenesis is the process by which new neurons are made. Although this occurs most intensely in children, certain regions of the brain persist in neurogenesis well into adulthood (21). The dentate gyrus of the hippocampus is one of these, producing neurons that migrate in their majority to the rest of the hippocampus (21). Music-evoked emotions have been shown to stimulate this region of the brain, and it is strongly speculated this also leads to the stimulation of neurogenesis therein (21). This would result in reduced atrophy in the anterior hippocampus, leading to improved mood and memory. This idea is supported by an observed increase in the rate of neuron recovery in post-stroke patients who received MT (5).

Improved affectation and affective cognition

robertkottke — 2024-04-15 19:23:26 UTC

AD patients have shown improvement in behavioral and psychological symptoms including depression, apathy, anxiety, and agitation following MT (21). AD patients respond to changes in the emotional content of music despite cognitive issues in similar areas (5). Multi-sensory forms of MT such as musical video games had a strong community response in assisted living homes and decreased scores on tests for depression and anxiety (5). MEAMs sparked strong emotional reactions in some cases (21). With MEAMs, AD patients reported feeling positively about their memory more often than younger patients.

Multi-domain improvement

robertkottke — 2024-04-15 19:25:45 UTC

Apart from the more strongly identified effects on memory indicated in two of the other effects, AD patients participating in MT also experienced improved psychomotor responses, global cognition, and executive function (23). Global cognition consists of an aggregated assessment of attention, memory, verbal fluency, visuospatial understanding, and more (24). MT did not reduce neuritic plaque, but patients exhibited reduced cortical atrophy and glucose hypometabolism in the brain (21). Music therapy seemed to be one of the stronger methods of promoting verbal fluency in AD patients (23). Active and receptive music therapy seem to affect separate cognitive domains to differing degrees (23).