This case-control study examines research visit summaries and magnetic resonance images for patients with frontotemporal lobar degeneration spectrum disorders and Alzheimer disease to determine the frequency and neuroanatomical characteristics of itching with undetermined origin.
Key Points
Question
What is the prevalence of itching with undetermined origin (IUO) in patients with frontotemporal degeneration spectrum disorders (FTLD-SD) and Alzheimer disease (AD), and what are the neuroanatomic correlates of IUO among those patients?
Findings
In this case-control study, which involved reviewing 2091 research visit summaries of 1112 patients, we observed a higher occurrence of itching in FTLD-SD compared with AD. Additionally, findings indicated that dysfunction in the right anterior insula and its connected regions contribute to dysregulation of the itching-scratching networks, resulting in uncontrollable itching or skin-picking.
Meaning
Itching and scratching occur frequently and early in patients with FTLD and should be considered in the differential diagnosis of IUO.
Abstract
Importance
Itching is common in geriatric populations and is frequently linked to dermatological or systemic conditions. Itching engages specific brain regions that are implicated in the pathogenesis of frontotemporal lobar degeneration spectrum disorders (FTLD-SD). Thus, itching of undetermined origin (IUO) may indicate the presence of a neurodegenerative process.
Objective
To compare the frequency of itching in FTLD-SD and Alzheimer disease (AD) and to determine the neuroanatomical underpinnings of IUO.
Design, Setting, and Participants
This case-control study evaluated data and brain magnetic resonance images (MRIs) for participants with FTLD-SD or AD. Participants of a research study on FTLD-SD at the University of California, San Francisco, Memory and Aging Center were evaluated from May 1, 2002, to December 31, 2021. The exposure group underwent structural brain MRI within 6 months of initial diagnosis. Research visit summaries were reviewed to validate qualitative details and accurately identify itching with undetermined origin (IUO).
Exposures
Symptoms suggestive of FTLD-SD or AD.
Main Outcomes and Measures
Frequency of itching in FTLD-SD and AD and neuroanatomic correlates.
Results
A total of 2091 research visit summaries were reviewed for 1112 patients exhibiting symptoms indicative of FTLD-SD or AD. From 795 records where itching or a related phrase was endorsed, 137 had IUO. A total of 454 participants were included in the study: 137 in the itching group (mean [SD] age, 62.7 [9.9] years; 74 [54%] females and 63 males [46%]) and 317 in the nonitching group (mean [SD] age, 60.7 [10.8] years; 154 [49%] females and 163 males [51%]). Groups were similar in age, sex, and disease severity. More frequent itching was found in FTLD-SD (95/248 patients [38%], of which 44 [46%] had behavioral variant frontotemporal dementia [bvFTD]) compared with the AD group (14/77 patients [18%]; P = .001). The odds of itching were 2.4 (95% CI, 1.48-3.97) times higher for FTLD-SD compared with all other cases of dementia. Compared with healthy controls, the group with IUO exhibited greater gray matter atrophy bilaterally in the amygdala, insula, precentral gyrus, and cingulum, as well as in the right frontal superior gyrus and thalamus. Among patients with bvFTD and itching vs bvFTD without itching, itching was associated with right-lateralized gray matter atrophy affecting the insula, thalamus, superior frontal gyrus, and cingulum.
Conclusions and Relevance
Among individuals with IUO, FTLD-SD was disproportionately represented compared with AD. In FTLD-SD, dysfunction in the right anterior insula and its connected regions, including the right precentral gyrus, cingulum, and bilateral amygdala, contribute to dysregulation of the itching-scratching networks, resulting in uncontrollable itching or skin picking. Awareness among physicians about the relationship between neurodegeneration and itching may help in the management of itch in older individuals. Further studies are needed to determine the best treatments for these symptoms in patients with neurodegenerative disorders.
Introduction
Itching is a common symptom that is particularly frequent among older individuals. The prevalence of chronic itching in geriatric populations is 25%, with dry skin or other comorbidities such as diabetes and chronic venous insufficiency the most common causes.1 Uncontrolled itching is associated with sleep disturbance, anxiety, decreased quality of life, and disruption of daily activities.2,3 Itching of undetermined origin (IUO) is diagnosed when no underlying cause can be identified.4,5,6 The neuroanatomical correlates of IUO have not yet been examined as related to neurodegenerative disorders.
The subjective experience of itching prompts a desire to scratch. While itching and scratching are related, they represent different aspects of the patient experience. Several brain regions are involved in itching, scratching, and itch relief. In healthy brains, synchronous activity of multiple brain areas is observed during itching, with some regions activated by the itch itself and others by the act of scratching. Often scratching can produce a pleasurable sensation and relief from the itch.7
Functional magnetic resonance imaging (MRI) or positron emission tomography in healthy individuals demonstrates that itching activates the thalamus, postcentral and precentral gyri, supplementary motor area, insula, cingulum, amygdala, and precuneus.8,9,10,11,12 In addition to the role in itch processing, these brain regions are also involved in emotions related to itch and to the motor reaction that this sensation can induce.7,11,12,13,14,15,16 The emotional and motivational components of itching play important roles in driving scratching behaviors, and individuals with chronic itching exhibit greater activation in several brain areas linked to emotions, including the insula and cingulum.10,12 Relieving an itch by scratching is associated with activation of reward circuits in limbic and ventral prefrontal areas.7,9
Scratching is accompanied by a robust deactivation of the anterior cingulum and insula that makes scratching rewarding and satisfying,7,14 indicating that these brain regions are important for itch relief. The insula has an integrative role, linking information from diverse systems to identify the need to itch and to facilitate relief.15,17 The insula is functionally and structurally connected to many brain regions, including the thalamus, amygdala, cingulum, superior and inferior frontal gyri, operculum, and precentral and postcentral gyri and also serves as a critical region for self-awareness, pain processing, and evaluating the intensity of a perceived itch. Additionally, in chronic itch conditions, the insula is activated bilaterally.12,14,18,19 Regions connected to the insula, such as the amygdala and cingulum, are involved in the affective and emotional aspects of the itch experience.7,14
Frontotemporal lobar degeneration spectrum disorders (FTLD-SD) encompass clinical disorders linked by common neuropathological changes and are characterized by changes in behavior, language, executive control, and often motor symptoms. FTLD-SD include a heterogeneous group of clinical syndromes, including behavioral variant frontotemporal dementia (bvFTD), nonfluent/agrammatic variant primary progressive aphasia (nfvPPA), semantic variant primary progressive aphasia (svPPA), progressive supranuclear palsy syndrome (PSP), and corticobasal syndrome (CBS). These disorders are associated with atrophy of frontal, temporal, and insular brain regions.20
Studies of FTLD-SD show an association between brain atrophy and behavioral symptoms such as apathy, loss of empathy, disinhibition, eating disorders, and aberrant motor behavior.21 Itching has not been evaluated in FTLD-SD, even though brain atrophy is prominent in the very regions associated with itching.21 Because atrophy in FTLD-SD involves brain regions that are essential components of the itching-scratching circuit, we evaluated IUO in patients with FTLD-SD vs Alzheimer disease (AD) vs healthy controls.
Methods
Study Design and Participant Selection
We conducted a case-control retrospective study of participants evaluated between May 1, 2002, and December 31, 2021, in a research study on FTLD-SD at the University of California, San Francisco, Memory and Aging Center. All participants or their legal representative signed consent forms approved by the ethics board. We followed Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for reporting this study.
Patients whose symptoms suggested FTLD-SD or AD were referred from community sources and from our academic programs. None were referred because of itching. All patients were categorized based on consensus clinical diagnosis of FTLD-SD (bvFTD, nfvPPA, svPPA, PSP, CBS) or AD using the appropriate prevailing clinical research criteria at the time of assessment.22,23,24,25,26,27,28,29,30,31,32 Participants underwent diagnostic determinations through a multidisciplinary consensus conference. The Clinical Dementia Rating (CDR) scale was used as a metric of disease severity. We selected participants with comprehensive research visit summaries whose links to their individual study identification allowed automated extraction of words for this analysis (n = 1112). All patients had symptoms suggestive of FTLD-SD or AD, but some cases did not meet published diagnostic criteria (n = 26 itching and 100 nonitching).
We searched all research visit summary notes for the term itching or related symptoms (Box) by using the advanced search function in Adobe Acrobat. This automated tool provided a comprehensive approach for multiple terms simultaneously, including phrases with multiple words. This facilitated identification of patterns or trends related to the selected terms, which were further analyzed and interpreted in the context of our research question. The summaries were then manually reviewed to validate the qualitative details and ensure accurate identification of IUO. We identified 795 records where itching or a related phrase was endorsed and 317 where itching was not. Subsequently, we excluded all cases with a clearly known cause of the itching, such as a skin condition, medication, or metabolic disorder. This resulted in 137 cases of IUO and 317 cases without itching (Figure 1).
Box. Words and Phrases Used in the Automated Search Related to the Term Itching.
Itching, itch, itchy, itchiness
Irritation (including irritation in the skin, skin irritation)
Scratching (scratch, scratched)
Rubbing
Pruritus (cutaneous pruritus)
Prickle, prickling
Stinging
Tingle, tingling
Tickling
Skin, skin lesion
Figure 1. Selection Approach for Itching and Nonitching Groups.
For image analysis, the subset within the itching group (n = 43) was paired in a 1:2 fashion with a nonitching counterpart (n = 86). This matching was executed by selecting individuals seen most recently, along with congruence in age range, Clinical Dementia Rating global score, and diagnosis. Subsequently, after magnetic resonance image (MRI) quality control, a total of 6 individuals from the itching group and 9 from the nonitching group were excluded from the analysis because of a low-quality MRI or movement artifacts noted. AD indicates Alzheimer disease; IUO, itching of undetermined origin; FTLD, frontotemporal lobar degeneration spectrum disorder.
Imaging Subgroups
We identified 43 patients in the itching group and 227 in the nonitching group with a structural brain MRI that included a T1-weighted sequence. All underwent structural brain MRI within 6 months of first diagnosis on either a 1.5-T, 3-T, or 4-T scanner. Imaging parameters were described previously.33,34,35 For imaging analysis, we formed a nonitching subgroup that was 2:1 matched to the itching group by age, disease severity (CDR score), and diagnosis (eg, bvFTD, nfvPPA, svPPA, PSP, CBS, or AD). In 2 instances, we did not have sufficient cases in an given age group and selected the oldest or youngest in the adjacent age decade (closest ages to this age range), resulting in 86 individuals in the nonitching group. Because of the small sample of our nonitching cohort (n = 227), we were unable to match the groups by sex. Subsequently, the T1-weighted structural images were visually checked to exclude artifacts and/or excessive motion. Fifteen individuals were excluded (6 from the itching group and 9 from the nonitching group), resulting in 37 individuals in the itching group and 77 in the nonitching group (Figure 1).
To conduct statistical comparisons, we selected a group of healthy controls (n = 75) from the healthy aging cohort that was best matched by age, sex, and scanner type of the itching group. Participants in the healthy aging cohort were enrolled in the Brain Aging Network for Cognitive Health (Branch) Study, which is a deeply phenotyped longitudinal cohort. The patients were diagnosed as clinically normal through a multidisciplinary consensus conference, which included a comprehensive neurological and neuropsychological assessment, CDR score, and informant interview. Additionally, all the participants in this group had undergone an imaging assessment (MRI).36,37
Image Processing
Images were preprocessed with the Computational Anatomy Toolbox (Structural Brain Mapping Group) in SPM12 running under MATLAB 2022a (MathWorks). Standard preprocessing included denoising, filtering, and bias correction. Tissue segmentation into gray matter (GM), white matter, and cerebrospinal fluid was performed with the SPM unified segmentation routine.38 Subsequently, the images were spatially normalized to the MNI space using an optimized geodesic shooting procedure39 and multiplied by the Jacobian determinants of the deformation field applied during spatial normalization to preserve the absolute amount of tissue. The modulated, normalized, GM-segmented images were finally smoothed with an 8-mm, full width at half maximum, Gaussian kernel.
Statistics
Behavioral Analyses
Descriptive statistics and demographic and clinical characteristics were assessed using a t test for independent group differences between continuous variables and χ2 tests for categorical data. Calculating odds ratios for risk of itching among FTLD, bvFTD, and AD compared with controls used logistic regression controlling for disease severity (CDR sum of boxes), sex, and age. We also completed a qualitative examination of the description of itching for those with IUO. Statistical analyses were performed with JASP version 0.17.1.
Neuroimaging Analysis
We performed a voxel-based morphometry analysis to compare GM volume loss between the groups only within selected regions of interests shown to be associated with itching and scratching behaviors.7,8,9,10,11,12,13,14,16,17,20,21,40,41,42 The regions analyzed included the insula and regions that are functionally or structurally connected to it, including the superior frontal gyrus/supplementary motor area, precentral and postcentral gyri, precuneus, cingulum, thalamus, and amygdala.17 18A binary mask of these regions was created using the Wake Forest University Health Sciences PickAtlas toolbox.
Analyses of variance were performed across groups; age, sex, total intracranial volume, and scanner type were included as nuisance covariates. We compared the (1) control group vs itching group, (2) control group vs nonitching group, (3) itching group vs nonitching group, and (4) participants diagnosed with bvFTD who reported itching (n = 15) vs those who did not (n = 31). Statistical thresholds were set at P < .05 and corrected for family-wise error for the comparison between patients and healthy controls and set at P < .05 and uncorrected for the direct comparisons between the 2 groups of patients.
Results
Participant Characteristics
A total of 2091 research visit summaries were reviewed for 1112 patients exhibiting symptoms indicative of FTLD-SD or AD. From 795 records where itching or a related phrase was endorsed, 137 had IUO. A total of 454 participants were included: 137 in the itching group (mean [SD] age, 62.7 [9.9] years; 74 females [54%] and 63 males [46%]) and 317 in the nonitching group (mean [SD] age, 60.7 [10.8] years; 154 females [49%] and 163 males [51%]). We noted similar age, sex, and disease severity in the itching and nonitching groups (Table).
Table. Characteristics of Itching Group Compared With Nonitching Group.
| Characteristic | Mean (SD) | P value | |
|---|---|---|---|
| Itching group | Nonitching group | ||
| No. of patients | 137 | 317 | |
| Age [range], y | 62.7 (9.9) [26-86] | 60.7 (10.8) [24-87] | .06 |
| Sex, No. (%) | |||
| Female | 74 (54) | 154 (49) | .39 |
| Male | 63 (46) | 163 (51) | |
| Global CDR score | 0.75 (0.63) | 0.78 (0.65) | .74 |
| Global CDR score group, No. (%) | NA | ||
| 0 | 16 (12) | 44 (14) | |
| 0.5 | 61 (45) | 129 (41) | |
| 1 | 26 (19) | 75 (24) | |
| 2 | 11 (8) | 34 (11) | |
| 3 | 3 (2) | 6 (2) | |
| CDR-SB score | 4.13 (4) | 4.34 (3.8) | .66 |
| FTLD-SB score | 5.40 (5) | 6 (5) | .29 |
Abbreviations: CDR, Clinical Dementia Rating; FTLD, Clinical Dementia Rating Scale for frontotemporal lobar degeneration; NA, not applicable; SB, sum of boxes.
Among patients in the itching group, 95 (69%) met diagnostic criteria for an FTLD-SD compared with 153 (48%) in the nonitching group (P < .001). The most frequently associated FTLD-SD clinical syndrome in the itching group was bvFTD (n = 44, 32%), followed by CBS (n = 21, 15%), PSP (n = 12, 9%), nfvPPA (n = 10, 7%), and svPPA (n = 8, 6%). Only 14 people in the itching group (10%) met diagnostic criteria for AD compared with 63 (20%) in the nonitching group (P = .01). Additionally, in the itching group, 2 patients met diagnostic criteria for logogenic variant PPA and 6 for amyotrophic lateral sclerosis. In the itching group, 44 patients (32%) met specific criteria for bvFTD whereas only 64 (20%) met bvFTD criteria in the nonitching group (P = .006).
Stated differently, we identified IUO in 95 of 248 participants (38%) with FTLD-SD, of which 44 (46%) had bvFTD, and in 14 of 77 participants (18%) with AD. After accounting for factors such as age, sex, and CDR sum-of-boxes (SB) scores, we observed that the odds of itching were 2.4 (95% CI, 1.48-3.97) times higher for FTLD-SD compared with all other cases of dementia. Our analysis revealed a similar difference among patients with bvFTD (odds ratio, 3.16; 95% CI, 1.44-6.90), who also displayed a 3-fold higher incidence of itching than those with AD. Regarding timing, itching was noted at CDR stage 0 for 16 cases (12%) and CDR 0.5 for 61 cases (45%) (Table).
Qualitative Description of Itching
In many patients, itching was repetitive, stereotyped, and compulsive in nature. In certain cases, it was characterized as a component of excessive body grooming. Typically, itching localized to the face, eyes, back, fingernails, arms, or legs. Most patients were unable to voluntarily cease itching, resulting in injuries such as scars. In 1 patient, repetitive itching of the left eye led to corneal damage requiring a corneal transplant. Another patient persistently picked at his fingernails, while yet another repeatedly rubbed their midforehead with the thumb, resulting in a keloid scar formation and prompting consideration of plastic surgery.
Image Analyses
By design, the imaging group was selected to match diagnoses across the itching and nonitching groups, resulting in approximately 69% in each group meeting criteria for an FTLD-SD clinical syndrome. The itching group had a mean (SD) age of 62.7 (9.7) years compared with 62.1 (9.1) years in the nonitching group and 64.7 (8.5) years among controls (P = .19). Sex differed across groups with 21 females (57%) in the itching group compared with 26 (34%) in the nonitching group and 45 (60%) in the control group (P = .003) (eTable 1 in Supplement 1).
The voxel-based analysis within the preselected regions across groups that had been matched by disease, age, sex, and CDR score revealed significant GM atrophy in the itching group compared with controls bilaterally in the amygdala, insula, precentral gyrus, and cingulum, as well as in the right frontal superior gyrus and thalamus (eTable 2 in Supplement 1). By contrast, the nonitching group showed GM atrophy bilaterally in the amygdala, insula, precentral gyrus, middle cingulum, and thalamus; in the left anterior cingulum, postcentral gyrus, and superior frontal gyrus; and in the right precuneus (eTable 2 in Supplement 1). The direct comparison between the itching group and the nonitching group revealed right-lateralized GM atrophy in the itching group in the anterior insula, precentral gyrus, and middle cingulum and bilaterally in the amygdala (Figure 2 and eTable 2 in Supplement 1).
Figure 2. Gray Matter Volume Comparison of the Itching Group vs the Nonitching Group.
This figure demonstrates greater right-lateralized gray matter atrophy in the anterior insula and precentral gyrus and bilaterally in the amygdala when comparing the itching with the nonitching group within preselected regions of interest (ROIs).
The direct comparison between the bvFTD itching vs bvFTD nonitching subgroups revealed right-lateralized GM atrophy in the itching group compared with the nonitching group in the anterior and posterior insula, thalamus, cingulum, and superior frontal gyrus and bilaterally in the supplementary motor area, precuneus, amygdala, and precentral and postcentral gyri (Figure 3 and eTable 3 in Supplement 1).
Figure 3. Gray Matter Volume Comparison Between the Behavioral Variant Frontotemporal Dementia (bvFTD) Patient Subgroups (Itching vs Nonitching).
This figure demonstrates gray matter atrophy observed in the right anterior and posterior insula, thalamus, and precentral gyrus when comparing the bvFTD itching group with the bvFTD nonitching group within preselected regions of interest (ROIs).
Discussion
Clinically, IUO is a troublesome symptom for physicians and their patients, but neurodegenerative conditions are rarely considered as a cause of IUO. Our study suggests that FTLD-SD is a potential cause of IUO. We found IUO in approximately 1 of 3 participants with FTLD-SD, and 1 of 2 with bvFTD. By contrast, in AD, IUO was uncommon (1 of 6 participants). Brain regions involved with itching were less severely affected in AD. In 1 other anatomically oriented study, excessive scratching and skin picking in humans was associated with a reduction in white matter tracts located near the bilateral anterior cingulate cortex.43,44 Scratching is a self-grooming behavior, reminiscent of the excessive grooming behaviors documented in mouse models of FTLD-SD with progranulin gene and tau mutations.45,46
In FTLD-SD, and in particular bvFTD, itching is common, and the anatomical correlates of this itching support a role for tissue dysfunction in itching and scratching circuits. Regional atrophy was greater in the anterior insula, precentral gyrus, and middle cingulum and bilaterally in the amygdala in participants with itching vs those without it. Another region associated with itching in this study is the insula, a cortical region linked with salience detection, self-awareness, interoception, pain processing, and addiction.18 Also, the insula is the major hub for visceroceptive or interoceptive inputs and is an essential component of the pain matrix, involved in the assessment of nociceptive stimulus intensity.16 Anterior insular cortex contains interoceptive representations that substantialize subjective feelings from the body and increase emotional awareness.47 As with pain, experimentally induced itch activates the anterior and posterior divisions of the insula. Further, the insula activates bilaterally in resting conditions in patients with end-stage kidney disease experiencing chronic itch, and this activation is strongly correlated with the perceived itch intensity.12 Itching involves similar pathways as pain, and both sensations are linked to the insula. Additionally, the insula is connected to the cingulum, and this connection is likely to be important in the process of planning to scratch.8,40
The amygdala is connected to the insula; itching activates the insula and the amygdala concurrently, and both deactivate with scratching and itch relief.7,40,48,49 The affective and emotional aspects of itch are represented in the activation of regions such as the amygdala.7,8,11 We found that atrophy bilaterally in the amygdala was more prominent in the itching group compared with the nonitching group and with controls, supporting an important role of dysfunction in the amygdala in the itching circuit and in the affective and emotional aspects of itch.
Precentral gyrus plays an important role in suppressing itching. Prior studies show that primary motor cortex activates during itching and deactivates following scratching.7,8 We found that severe atrophy in the right anterior insula, right cingulum, and right precentral gyrus is associated with IUO in FTLD-SD, linking dysfunction in these areas to the itching-scratching circuit. These brain regions are essential for itch relief, and neurodegeneration involving the itching-scratching circuit may lead to debilitating itch and ineffective activity of brain regions responsible for itch relief and cessation of scratching.
Remarkably, with itching in the setting of FTLD-SD, the most atrophic brain areas in the itching group were localized to the right hemisphere. Prior studies support involvement of the right hemisphere in mediating social and emotional behavior, such as socially aberrant motor behavior.21 The cause of the itching and scratching in these patients remains complex and likely multifactorial. In IUO, some of the repetitive scratching is related to emotional and behavioral changes.50,51,52,53 The behaviors described in this article share clinical phenomenology with other movement disorders such as tics and behaviors related to obsessive-compulsive disorder.54 In many of the patients, the itching was performed to alleviate an unpleasant sensation. In others, the itching was spontaneous without concerns about discomfort in the skin as has been reported previously.55 Also, somatic delusions can lead to skin picking, although this was not specifically noted in these patients.56 Because of the potential variability in the phenomenology of the itching, the anatomic correlates may reflect anatomic variability.
While the central mechanisms of itch are being studied, more research is needed to examine the relationship between itching and neurodegeneration. Our study adds to the understanding of itching and neurodegeneration and suggests that it is a common and troubling behavior in FTLD-SD. Identifying the underlying cause of itch is important because it enables clinicians to choose the most appropriate treatment. For example, if the underlying cause involves obsessions and/or compulsions, a selective serotonin reuptake inhibitor might be a logical choice of therapy.57,58 Similarly, in cases of itching secondary to brain neurodegeneration, treatment should be tailored to the underlying cause, and the effectiveness of treatments such as selective serotonin reuptake inhibitors and gabapentin should be considered in future studies.59,60
Limitations
The study design did not allow further characterization of itching because it was retrospective, and the findings are based on what patients and caregivers reported in their medical records. Because FTLD-SD attacks early (57% by CDR 0.5) the regions involved with the generation and relief of itching, it is not surprising that IUO may occur in the earliest stages of FTLD-SD, even before a diagnosis has been made.
The study is further limited by the medium-sized sample of individuals with available MRIs in the itching group particularly for our comparison of itching vs nonitching in bvFTD. Also there were few cases of AD within the itching group; thus, we did not examine correlates in AD. Given the retrospective nature of our study, a precise quantitative assessment of itching was not feasible.
Conclusions
This study showed that compared with participants without itching, those with itching exhibited severe brain atrophy in the right anterior insula, right precentral gyrus, right cingulum, and bilateral amygdala, highlighting a possible underlying cause of itching in patients with FLTD-SD. Itch and pain share similar brain pathways, including the anterior and posterior insula and sensory motor cortex; understanding their interplay enriches the understanding of sensory processing. The importance of this study is to increase awareness among physicians about the relationship between neurodegeneration and itching, which may help in the management of itch in older individuals. Further studies are needed to determine the best treatments for these bothersome symptoms in patients with neurodegenerative disorders.
eTable 1. Characteristics of the imaging subgroups (Itching, non-itching, controls)
eTable 2. ROI comparison between Itching vs Non itching group and vs healthy controls
eTable 3. ROI analysis comparison between the bvFTD Itching vs non-itching
Data sharing statement
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eTable 1. Characteristics of the imaging subgroups (Itching, non-itching, controls)
eTable 2. ROI comparison between Itching vs Non itching group and vs healthy controls
eTable 3. ROI analysis comparison between the bvFTD Itching vs non-itching
Data sharing statement