Hearing and music in dementia

Abstract

Music is a complex acoustic signal that relies on a number of different brain and cognitive processes to create the sensation of hearing. Changes in hearing function are generally not a major focus of concern for persons with a majority of neurodegenerative diseases associated with dementia, such as Alzheimer disease (AD). However, changes in the processing of sounds may be an early, and possibly preclinical, feature of AD and other neurodegenerative diseases. The aim of this chapter is to review the current state of knowledge concerning hearing and music perception in persons who have a dementia as a result of a neurodegenerative disease. The review focuses on both peripheral and central auditory processing in common neurodegenerative diseases, with a particular focus on the processing of music and other non-verbal sounds. The chapter also reviews music interventions used for persons with neurodegenerative diseases.

Keywords: Alzheimer's disease; Parkinson's disease; auditory evoked potentials; corticobasal degeneration; environmental sounds; frontotemporal dementia; melody; neurodegenerative disease; progressive supranuclear palsy; rhythm.

Fig. 37.1

Cognitive model of music processing. Each box represents a processing component, and arrows represent pathways of information flow or communication between processing components. A neurologic anomaly may either damage a processing component (box) or interfere with the flow of information between two boxes. All components whose domains appear to be specific to music are in green; others are in blue. There are three neurally individuated components in italics – rhythm analysis, meter analysis, and emotion expression analysis – whose specificity to music is currently unknown. They are represented here in blue, but future work may provide evidence for representing them in green. (Reproduced from Peretz and Coltheart, 2003, with permission.)

Fig. 37.2

Brain areas implicated in disorders of music listening. Critical brain substrates for musical-listening disorders across studies. Five cartoons are shown, each depicting the brain in a schematic axial section that includes all key anatomic areas involved in music listening (identified on the top cartoon); the corpus callosum (black), superior temporal plane (light gray), and middle/inferior temporal gyri (dark gray areas, in exploded view) are colored for ease of identification. Musical functions analyzed in Supplementary Table 1 have been grouped as follows: pitch processing (pitch interval, pitch pattern, tonal structure, timbre); temporal processing (time interval, rhythm); musical memory (familiar and novel material); and emotional response to music. Each group of functions is assigned to a separate cartoon; individual functions are identified to the right of the corresponding cartoon. Raw data from Supplementary Table 1 have been thresholded; the presence of a colored circle corresponding to a particular function in a region indicates that at least 50% of studies of the function implicate that region. The size of each circle is scaled according to the proportion of studies of the function implicating that region (see text). Meter is not represented as no brain area was implicated in 50% or more of cases. amyg, amygdala; aSTG, anterior superior temporal gyrus; bg, basal ganglia; cc, corpus callosum; r, frontal; hc, hippocampal; HG, Heschl’s gyrus; ic, inferior colliculi; i, inferior; ins, insula; l, lateral; m, medial; thal, thalamus; PT, planum temporale; TG, temporal gyrus. (Reproduced from Stewart et al., 2006, with permission.)

Fig. 37.3

Identification of emotions in music by persons with Parkinson’s disease (PD). Box plot of the scores on the four subtests of the emotion recognition task in PD patients (black lines, gray boxes) and controls (gray lines, white boxes). On the happiness subtest all subjects obtained the maximum score, except two subjects (+). For the fear recognition subtask, none of the controls scored below 5, therefore the downward error bar is absent. (Reproduced from van Tricht et al., 2010, with permission.)

Fig. 37.4

Correlation between performance on music emotions task and brain atrophy. Voxel-based morphometry analyses showing brain regions that correlate with recognition of musical emotions (MNI ,×= −46, y = −12, z = −46; top right: MNI,×= 40, y = 6, z = −48), Colored voxels are significant at P < 0.001 uncorrected, except for ROCF , where P < 0.01 uncorrected is displayed. (Reproduced from Hsieh et al., 2012, with permission.)

Fig. 37.5

Category-specific contrast effects sampled at previously specified foci of category-specific semantic sound processing. Bars show mean effect sizes (proportionate to percent BOLD signal change) for the control and semantic dementia (SD) patient groups separately for the category-specific semantic contrast at pre-specified foci of category-specific auditory processing (based on Lewis et al., 2005); 95% confidence intervals are also displayed. The upper panels show effects at foci previously associated with animal sound processing in the contrast assessing category-specific semantic processing favouring animal sounds, [(mful_a–mless_a)–(mful_t–mless_t)]; whilst the lower panels show effects at foci previously associated with tool sound processing in the reverse contrast assessing category-specific semantic processing favouring tool sounds, [(mful_t – mless_t) – (mful_a – mless_a)]. Asterisks above bars indicate significance levels for the control and SD groups separately; asterisks above brackets indicate significance levels for between group comparisons. KEY: *p < 0.05; **p < 0.01; ***p < 0.001; mSTG, middle superior temporal gyrus; pLaS, posterior lateral sulcus; pMTG, posterior middle temporal gyrus; SD, semantic dementia.

Fig. 37.6

Statistical parametric maps showing activation profiles for perceptual and semantic processing of environmental sounds in healthy controls and patients with semantic dementia. Statistical parametric maps show clusters (formed at whole brain uncorrected height threshold p < 0.001) that are significant at extent threshold p < 0.05, FWE-corrected for multiple comparisons over the whole brain. Maps are rendered on a composite mean normalised structural brain image (see Section Analysis of fMRI data); the left hemisphere is shown on the left for all coronal and axial sections. For sagittal and coronal sections the plane is indicated using MNI coordinates. All axial slices are tilted parallel to the superior temporal plane to show key auditory regions; the anatomical plane of view is indicated. KEY: SD, semantic dementia; STP, superior temporal plane; STS, superior temporal sulcus. The colour key follows. Panels a and b: the colour bar (left) codes voxel-wise T scores for contrast [meaningless sounds > silence]. Panel c: all clusters showing a significant interaction with group (patient > control) for the contrast [all meaningless sounds > silence] are depicted in either magenta or cyan. Magenta codes voxels in which controls alone showed greater activation in the reverse contrast ([silence > meaningful sounds]) than the forwards ([meaningless sounds > silence]) contrast, indicating that the group interaction within these voxels may be driven by greater activation for controls compared to patients in the reverse contrast; however, remaining voxels, coded in cyan, are likely to be driven by greater activation for patients compared to controls in the forwards contrast. Panels d and e: green codes significant clusters in the contrast assessing the category-specific semantic processing favouring animal sounds, [(mful_a–mless_a)–(mful_t–mless_t)]; blue codes significant clusters in the contrast assessing category-specific semantic processing favouring tool sounds, [(mful_t–mless_t)–(mful_a–mless_a)]. Panel f: all clusters showing a significant interaction with group (patient > control) for the contrast assessing category-specific semantic processing favouring animal sounds are depicted in either magenta or cyan. Magenta codes voxels in which controls alone showed greater activation in the reverse contrast (category-specific semantic processing favouring tool sounds) than the forwards (category-specific semantic processing favouring animal sounds) contrast, indicating that the group interaction within these voxels may be driven by greater activation for controls compared to patients in the reverse contrast; however, remaining voxels, coded in cyan, are likely to be driven by greater activation for patients compared to controls in the forwards contrast. (Reproduced from Goll et al., 2012b, with permission.)

Fig. 37.7

P50 and N100 results for five subject groups. Event-related potentials to non-targets during the baseline session in all older subjects (A), mild cognitive impairment (MCI) subtypes (B), and young and older controls (C). (D) P50 amplitudes from individual MCI subjects (MCI single domain (MCI-SD) and MCI multiple domain (MCI-MD)). Mean ± 1 SD from controls are also shown for comparison. Group comparisons of P50 (E) and N100 (F) amplitudes. Note that in panel F negative potentials are plotted upwards because the N100 is negative in polarity. Vertical lines indicate stimulus onset. Asterisks show post hoc tests indicating significant differences between pairs of groups, shown by insert (*P < 0.05, **P < 0.01). (Reprinted from Golob et al., 2007, with permission.)