Cortical neuroanatomical changes related to specific language impairments in primary progressive aphasia.

Objective: Language function test-specific neural substrates in Korean patients with primary progressive aphasia (PPA) might differ from those in other causes of dementia and English-speaking PPA patients. We investigated the correlation between language performance tests and cortical thickness to determine neural substrates in Korean patients with PPA. Materials and methods: Ninety-six patients with PPA were recruited from the memory clinic. To acquire neural substrates, we performed linear regression using the scores of each language test as a predictor, cortical thickness as an outcome and age, sex, years of education, and intracranial volume as confounders. Results: Poor performance in each language function test was associated with lower cortical thickness in specific cortical regions: (1) object naming and the bilateral anterior to mid-portion of the lateral temporal and basal temporal regions; (2) semantic generative naming and the bilateral anterior to mid-portion of the lateral temporal and basal temporal regions; (3) phonemic generative naming and the left prefrontal and inferior parietal regions; and (4) comprehension and the left posterior portion of the superior and middle temporal regions. In particular, the neural substrates of the semantic generative naming test in PPA patients, left anterior to mid-portion of the lateral and basal temporal regions, quite differed from those in patients with other causes of dementia. Conclusion: Our findings provide a better understanding of the different pathomechanisms for language impairments among PPA patients from those with other causes of dementia.

Detection and differentiation of ataxic and hypokinetic dysarthria in cerebellar ataxia and parkinsonian disorders via wave splitting and integrating neural networks.

Dysarthria may present during the natural course of many degenerative neurological conditions. Hypokinetic and ataxic dysarthria are common in movement disorders and represent the underlying neuropathology. We developed an artificial intelligence (AI) model to distinguish ataxic dysarthria and hypokinetic dysarthria from normal speech and differentiate ataxic and hypokinetic speech in parkinsonian diseases and cerebellar ataxia. We screened 804 perceptual speech analyses performed in the Samsung Medical Center Neurology Department between January 2017 and December 2020. The data of patients diagnosed with parkinsonian disorders or cerebellar ataxia were included. Two speech tasks (numbering from 1 to 50 and reading nine sentences) were analyzed. We adopted convolutional neural networks and developed a patch-wise wave splitting and integrating AI system for audio classification (PWSI-AI-AC) to differentiate between ataxic and hypokinetic speech. Of the 395 speech recordings for the reading task, 76, 112, and 207 were from normal, ataxic dysarthria, and hypokinetic dysarthria subjects, respectively. Of the 409 recordings of the numbering task, 82, 111, and 216 were from normal, ataxic dysarthria, and hypokinetic dysarthria subjects, respectively. The reading and numbering task recordings were classified with 5-fold cross-validation using PWSI-AI-AC as follows: hypokinetic dysarthria vs. others (area under the curve: 0.92 ± 0.01 and 0.92 ± 0.02), ataxia vs. others (0.93 ± 0.04 and 0.89 ± 0.02), hypokinetic dysarthria vs. ataxia (0.96 ± 0.02 and 0.95 ± 0.01), hypokinetic dysarthria vs. none (0.86 ± 0.03 and 0.87 ± 0.05), and ataxia vs. none (0.87 ± 0.07 and 0.87 ± 0.09), respectively. PWSI-AI-AC showed reliable performance in differentiating ataxic and hypokinetic dysarthria and effectively augmented data to classify the types even with limited training samples. The proposed fully automatic AI system outperforms neurology residents. Our model can provide effective guidelines for screening related diseases and differential diagnosis of neurodegenerative diseases.

Clinical Characteristic in Primary Progressive Aphasia in Relation to Alzheimer's Disease Biomarkers.

BACKGROUND: Primary progressive aphasia (PPA) is associated with amyloid-ß (Aß) pathology. However, clinical feature of PPA based on Aß positivity remains unclear. OBJECTIVE: We aimed to assess the prevalence of Aß positivity in patients with PPA and compare the clinical characteristics of patients with Aß-positive (A+) and Aß-negative (A-) PPA. Further, we applied Aß and tau classification system (AT system) in patients with PPA for whom additional information of in vivo tau biomarker was available. METHODS: We recruited 110 patients with PPA (41 semantic [svPPA], 27 non-fluent [nfvPPA], 32 logopenic [lvPPA], and 10 unclassified [ucPPA]) who underwent Aß-PET imaging at multi centers. The extent of language impairment and cortical atrophy were compared between the A+ and A-PPA subgroups using general linear models. RESULTS: The prevalence of Aß positivity was highest in patients with lvPPA (81.3%), followed by ucPPA (60.0%), nfvPPA (18.5%), and svPPA (9.8%). The A+ PPA subgroup manifested cortical atrophy mainly in the left superior temporal/inferior parietal regions and had lower repetition scores compared to the A-PPA subgroup. Further, we observed that more than 90% (13/14) of the patients with A+ PPA had tau deposition. CONCLUSION: Our findings will help clinicians understand the patterns of language impairment and cortical atrophy in patients with PPA based on Aß deposition. Considering that most of the A+ PPA patents are tau positive, understanding the influence of Alzheimer's disease biomarkers on PPA might provide an opportunity for these patients to participate in clinical trials aimed for treating atypical Alzheimer's disease.

Differences in neuroimaging features of early- versus late-onset nonfluent/agrammatic primary progressive aphasia.

This study investigated distinct neuroimaging features measured by cortical thickness and subcortical structural shape abnormality in early-onset (EO, onset age <65 years) and late-onset (LO, onset age ≥65 years) nonfluent/agrammatic variant of primary progressive aphasia (nfvPPA) patients. Cortical thickness and subcortical structural shape analyses were performed using a surface-based method from 38 patients with nfvPPA and 76 cognitively normal individuals. To minimize the effects of physiological aging, we used W-scores in comparisons between the groups. The EO-nfvPPA group exhibited more extensive cortical thickness reductions predominantly in the left perisylvian, lateral and medial prefrontal, temporal, posterior cingulate, and precuneus regions than the LO-nfvPPA group. The EO-nfvPPA group also exhibited significantly greater subcortical structural shape abnormality than the LO-nfvPPA group, mainly in the left striatum, hippocampus, and amygdala. Our findings suggested that there were differences in neuroimaging features between these groups by the age of symptom onset, which might be explained by underlying heterogeneous neuropathological differences or the age-related brain reserve hypothesis.

Relationships between [¹8F]-THK5351 Retention and Language Functions in Primary Progressive Aphasia.

BACKGROUND AND PURPOSE: There are three distinct subtypes of primary progressive aphasia (PPA): the nonfluent/agrammatic variant (nfvPPA), the semantic variant (svPPA), and the logopenic variant (lvPPA). We sought to characterize the pattern of [¹8F]-THK5351 retention across all three subtypes and determine the topography of [¹8F]-THK5351 retention correlated with each neurolinguistic score. METHODS: We enrolled 50 participants, comprising 13 PPA patients (3 nfvPPA, 5 svPPA, and 5 lvPPA) and 37 subjects with normal cognition (NC) who underwent 3.0-tesla magnetic resonance imaging, [¹8F]-THK5351 positron-emission tomography scans, and detailed neuropsychological tests. The PPA patients additionally participated in extensive neurolinguistic tests. Voxel-wise and region-of-interest-based analyses were performed to analyze [¹8F]-THK5351 retention. RESULTS: The nfvPPA patients exhibited higher [¹8F]-THK5351 retention in the the left inferior frontal and precentral gyri. In svPPA patients, [¹8F]-THK5351 retention was elevated in the anteroinferior and lateral temporal cortices compared to the NC group (left>right). The lvPPA patients exhibited predominant [¹8F]-THK5351 retention in the inferior parietal, lateral temporal, and dorsolateral prefrontal cortices, and the precuneus (left>right). [¹8F]-THK5351 retention in the left inferior frontal area was associated with lower fluency scores. Comprehension was correlated with [¹8F]-THK5351 retention in the left temporal cortices. Repetition was associated with [¹8F]-THK5351 retention in the left inferior parietal and posterior temporal areas, while naming difficulty was correlated with retention in the left fusiform and temporal cortices. CONCLUSIONS: The pattern of [¹8F]-THK5351 retention was well matched with clinical and radiological findings for each PPA subtype, in agreement with the anatomical and functional location of each language domain.

18F-THK5351 PET Imaging in Nonfluent-Agrammatic Variant Primary Progressive Aphasia.

BACKGROUND AND PURPOSE: To analyze 18F-THK5351 positron emission tomography (PET) scans of patients with clinically diagnosed nonfluent/agrammatic variant primary progressive aphasia (navPPA). METHODS: Thirty-one participants, including those with Alzheimer's disease (AD, n=13), navPPA (n=3), and those with normal control (NC, n=15) who completed 3 Tesla magnetic resonance imaging, 18F-THK5351 PET scans, and detailed neuropsychological tests, were included. Voxel-based and region of interest (ROI)-based analyses were performed to evaluate retention of 18F-THK5351 in navPPA patients. RESULTS: In ROI-based analysis, patients with navPPA had higher levels of THK retention in the Broca's area, bilateral inferior frontal lobes, bilateral precentral gyri, and bilateral basal ganglia. Patients with navPPA showed higher levels of THK retention in bilateral frontal lobes (mainly left side) compared than NC in voxel-wise analysis. CONCLUSIONS: In our study, THK retention in navPPA patients was mainly distributed at the frontal region which was well correlated with functional-radiological distribution of navPPA. Our results suggest that tau PET imaging could be a supportive tool for diagnosis of navPPA in combination with a clinical history.

Cognitive and Motor Aspects of Parkinson's Disease Associated with Dysphagia.

BACKGROUND: Dysphagia is a common symptom and an important prognostic factor in Parkinson's disease (PD). Although cognitive and motor dysfunctions may contribute to dysphagia in patients with PD, any specific association between such problems and swallowing functions is unclear. Here, we examined the potential relationship between cognitive/motor components and swallowing functions in PD. We evaluated the contributions of cognition and motor function to the components of swallowing via video fluoroscopic swallowing (VFS) experiments. METHODS: We prospectively enrolled 56 patients without dementia having PD. Parkinson's disease severity was assessed by the Unified Parkinson's Disease Rating Scale (UPDRS). All participants received neuropsychological tests covering general mental status, visuospatial function, attention, language, learning and memory, and frontal executive function. The well-validated "modified barium swallow impairment profile" scoring system was applied during VFS studies to quantify swallowing impairments. Finally, correlations between neuropsychological or motor functions and impairment in swallowing components were calculated. RESULTS: The most significant correlations were found between the frontal/executive or learning/memory domains and the oral phase of swallowing, though a minor component of the pharyngeal phase correlated with frontal function as well. Bradykinesia and the UPDRS total score were associated with both the pharyngeal and oral phases. CONCLUSIONS: Our findings suggest that cognitive dysfunctions are associated with the oral phase of swallowing in patients with early stage PD while the severity of motor symptoms may be associated with overall swallowing function.

Differences in early speech patterns between Parkinson variant of multiple system atrophy and Parkinson's disease.

In Parkinson variant of multiple system atrophy (MSA-P), patterns of early speech impairment and their distinguishing features from Parkinson's disease (PD) require further exploration. Here, we compared speech data among patients with early-stage MSA-P, PD, and healthy subjects using quantitative acoustic and perceptual analyses. Variables were analyzed for men and women in view of gender-specific features of speech. Acoustic analysis revealed that male patients with MSA-P exhibited more profound speech abnormalities than those with PD, regarding increased voice pitch, prolonged pause time, and reduced speech rate. This might be due to widespread pathology of MSA-P in nigrostriatal or extra-striatal structures related to speech production. Although several perceptual measures were mildly impaired in MSA-P and PD patients, none of these parameters showed a significant difference between patient groups. Detailed speech analysis using acoustic measures may help distinguish between MSA-P and PD early in the disease process.

Structural brain changes after traditional and robot-assisted multi-domain cognitive training in community-dwelling healthy elderly.

UNLABELLED: The purpose of this study was to investigate if multi-domain cognitive training, especially robot-assisted training, alters cortical thickness in the brains of elderly participants. A controlled trial was conducted with 85 volunteers without cognitive impairment who were 60 years old or older. Participants were first randomized into two groups. One group consisted of 48 participants who would receive cognitive training and 37 who would not receive training. The cognitive training group was randomly divided into two groups, 24 who received traditional cognitive training and 24 who received robot-assisted cognitive training. The training for both groups consisted of daily 90-min-session, five days a week for a total of 12 weeks. The primary outcome was the changes in cortical thickness. When compared to the control group, both groups who underwent cognitive training demonstrated attenuation of age related cortical thinning in the frontotemporal association cortices. When the robot and the traditional interventions were directly compared, the robot group showed less cortical thinning in the anterior cingulate cortices. Our results suggest that cognitive training can mitigate age-associated structural brain changes in the elderly. TRIAL REGISTRATION: ClnicalTrials.gov NCT01596205.

Agraphia caused by acute right parietal infarction.

Injury in the dominant language hemisphere typically leads to agraphia, however we report a patient with agraphia after injury to the right angular gyrus. A 71-year-old Korean woman presented with the complaint of an inability to write for the last 7 days. The patient had been illiterate for most of her life, but had started learning to write Hangul, the Korean alphabet, at a welfare center 3 years ago. On language screening she was unable to write although she could read, and other language functions showed no abnormalities. Brain MRI showed acute infarction in the right angular gyrus. Her writing patterns displayed features of surface agraphia, indicative of phoneme-to-grapheme conversion with phonetic writing of targets. Additionally, she manifested visual errors. A functional MRI indicated that her left hemisphere was language dominant. This patient experienced agraphia resulting from pure impairment of visuo-constructive function after acute infarction in the right angular gyrus.

Postmorbid learning of saxophone playing in a patient with frontotemporal dementia.

Some patients with frontotemporal dementia (FTD) show an artistic enhancement of musical abilities. However, no patients with FTD, to date, have been reported to be able to learn how to play a musical instrument after disease onset. Herein we describe a patient (J. K.) who had never played any musical instruments premorbidly, but who learned to play the saxophone after being diagnosed with a behavioral variant of FTD. He mastered a repertoire that consisted of 10 pieces of Korean folk songs over a period of three years. Furthermore, his saxophone skills were high enough to outperform other students in his class.

Higher education affects accelerated cortical thinning in Alzheimer's disease: a 5-year preliminary longitudinal study.

BACKGROUND: Epidemiological studies have reported that higher education (HE) is associated with a reduced risk of incident Alzheimer's disease (AD). However, after the clinical onset of AD, patients with HE levels show more rapid cognitive decline than patients with lower education (LE) levels. Although education level and cognition have been linked, there have been few longitudinal studies investigating the relationship between education level and cortical decline in patients with AD. The aim of this study was to compare the topography of cortical atrophy longitudinally between AD patients with HE (HE-AD) and AD patients with LE (LE-AD). METHODS: We prospectively recruited 36 patients with early-stage AD and 14 normal controls. The patients were classified into two groups according to educational level, 23 HE-AD (>9 years) and 13 LE-AD (≤9 years). RESULTS: As AD progressed over the 5-year longitudinal follow-ups, the HE-AD showed a significant group-by-time interaction in the right dorsolateral frontal and precuneus, and the left parahippocampal regions compared to the LE-AD. CONCLUSION: Our study reveals that the preliminary longitudinal effect of HE accelerates cortical atrophy in AD patients over time, which underlines the importance of education level for predicting prognosis.

Amyloid deposition in early onset versus late onset Alzheimer's disease.

BACKGROUND: Patients with early-onset Alzheimer's disease (EOAD) may differ from those with late-onset Alzheimer's disease (LOAD) in cognitive impairment profiles and clinical course. Postmortem studies also reported that EOAD has a greater pathologic burden than LOAD. We examined the effects of age at onset on the burden and distribution of amyloid plaques in patients with AD, using a statistical parametric mapping (SPM) and regions of interest (ROIs) analyses of the Pittsburgh compound B (PiB)-PET. METHODS: We initially recruited 72 patients with AD who had completed the [11C] PiB-PET scan, but four patients were excluded due to familial AD or incomplete MRI data. Of the 68 patients, 61 were classified as PiB-positive (PiB+) and seven as PiB-negative (PiB-) using the measured global PiB uptake ratio values. Of the 61 patients with PiB+ AD, in order to maximize the effect of onset age, we excluded 20 patients in their 60 s. Thus among the remaining 41 patients, the amyloid deposition of only 17 patients with EOAD (age onset <60 years) and 24 patients with LOAD (onset age ≥70 years) were compared. RESULTS: There were no significant differences in the global mean PiB index between EOAD and LOAD patients, whereas SPM and ROIs analyses showed that those with EOAD retained higher levels of PiB in the bilateral basal ganglia, bilateral thalamus, left superior temporal cortex, and left cuneus compared to those with LOAD. CONCLUSION: Our findings demonstrated that EOAD patients differed from those with LOAD in the topography of amyloid deposition, which may partly account for the findings from previous studies that extrapyramidal symptoms and frontal dysfunction are more common in EOAD than in LOAD patients.

Cerebellar atrophy in patients with subcortical-type vascular cognitive impairment.

Recent studies suggest that the role of the cerebellum extends into cognitive regulation and that subcortical vascular dementia (SVaD) can result in cerebellar atrophy. However, there has been no evaluation of the cerebellar volume in the preclinical stage of SVaD. We aimed to compare cerebellar volume among patients with amnestic mild cognitive impairment (aMCI) and subcortical vascular mild cognitive impairment (svMCI) and evaluate which factors could have contributed to the cerebellar volume. Participants were composed of 355 patients with aMCI, svMCI, Alzheimer's disease (AD), and SVaD. Cerebellar volumes were measured using automated methods. A direct comparison of the cerebellar volume in SVaD and AD groups showed that the SVaD group had a statistically smaller cerebellar volume than the AD group. Additionally, the svMCI group had a smaller cerebellar volume than the aMCI group, with the number of lacunes (especially in the supratentorial regions) being associated with cerebellar volume. Cerebellar volumes were associated with some neuropsychological tests, digit span backward and ideomotor apraxia. These findings suggest that cerebellar atrophy may be useful in differentiating subtypes of dementia and the cerebellum plays a potential role in cognition.

Dysgraphia in Korean patients with Alzheimer's disease as a manifestation of bilateral hemispheric dysfunction.

BACKGROUND: In writing, linguistic (i.e., spelling) and nonlinguistic (i.e., arranging strokes or letters) functions are processed by the left and right hemispheres, respectively. The configuration of Korean alphabet, 'Hangul' invokes nonlinguistic, visuospatial functions that other writing systems use less extensively. Patients with Alzheimer's disease (AD) have bilateral involvement of temporoparietal-frontal areas that are responsible for processing language and visuospatial functions. OBJECTIVES: The aim of this study was to examine the nature of Hangul writing dysfunction, which may be associated with bilateral hemispheric impairments in AD. METHODS: A sample of 75 patients with AD and 20 healthy controls (HC) performed a Hangul writing task. Neuroimaging positron emission tomography (PET) data of 22 patients were utilized to measure the regional brain glucose metabolism associated with Hangul writing. RESULTS: The writing performance of the AD group was significantly reduced and different types of errors were observed as the disease got worse. Glucose hypometabolism correlated with Hangul writing impairment was located in the right occipitotemporal lobe and left temporoparietal lobe. CONCLUSIONS: The PET findings demonstrate that impairment in Hangul writing performance in Korean AD patients is closely related to a functional decline in both the right and left hemispheres. The study provides a unique contribution to the knowledge of dysgraphia in a non-alphabetical writing system as well as the underlying neuropathology of dysgraphic features in such languages.

The cortical neuroanatomy of neuropsychological deficits in mild cognitive impairment and Alzheimer's disease: a surface-based morphometric analysis.

Patients with probable Alzheimer's disease (AD) and the amnesic form of mild cognitive impairment (aMCI) often demonstrate several types of neuropsychological deficits. These deficits are often related to cortical atrophy, induced by neuronal degradation. The purpose of this study is to investigate whether different anatomic patterns of cortical atrophy are associated with specific neuropsychological deficits. The participants were 170 patients with AD and 99 patients with aMCI. All participants underwent the Seoul Neuropsychological Screening Battery (SNSB), which includes tests that assess attention, language, visuospatial functions, verbal and visual memory, and frontal/executive functions. Cortical atrophy (thinning) was quantified by measuring the thickness of the cortical mantle across the entire brain using automated, three-dimensional magnetic resonance imaging. The relationship between cortical thickness and neuropsychological performance was analysed using stepwise multiple linear regression analyses. These analyses (corrected P<.001) showed that several specific brain regions with cortical thinning were associated with cognitive dysfunction including: digit span backward, verbal and picture recall, naming and fluency, drawing-copying, response inhibition and selective attention. Some of the other functions, however, were not associated with specific foci of cortical atrophy (digit span forward, the word reading portion of the Stroop test, word and picture recognition). Our study, involving a large sample of participants with aMCI and AD, provides support for the postulate that cortical thinning-atrophy in specific anatomic loci are pathological markers for specific forms of cognitive dysfunction.

Agraphia in Korean patients with early onset Alzheimer's disease.

BACKGROUND: Agraphia in Korean patients may be different from agraphia in other patients who use alphabetical writing systems due to the "visuoconstructional script" characteristics of the Korean writing system, Hangul. Patients with early onset Alzheimer's disease (EOAD) have a severe degree of hypometabolism in the parietal area, which is known to be involved in processing visuospatial function. Thus, we explored the diverse error patterns manifested in writing single syllables in Korean patients with EOAD. METHODS: A study sample of 35 patients with EOAD and 18 healthy controls (HC) performed a Hangul writing task. We analyzed the erroneous responses of the subjects according to visuoconstructional and linguistic characteristics. In addition, we evaluated the relationship between Hangul writing and the neuropsychological variables as well as the severity of dementia. RESULTS: When comparing the total number of erroneous responses between EOAD and HC groups, the performances of EOAD patients were significantly worse than those of HC. EOAD patients demonstrated visuoconstructional errors even in the early stages of the disease. Severity of dementia and multiple cognitive domains such as attention, language, immediate memory, and frontal executive functions significantly correlated with the performance of Hangul writing. CONCLUSION: Our findings suggest that patients with EOAD exhibit not only linguistic errors but also visuoconstructional manifestations of agraphia, which are associated with cognitive impairments in the multiple domains.

Pure word deafness in a patient with early-onset Alzheimer's disease: an unusual presentation.

BACKGROUND AND PURPOSE: The occurrence of PWD in neurodegenerative disease is very rare, and this is the first report of it being related to early-onset AD. We describe a patient with early-onset Alzheimer's disease (AD) who presented with pure word deafness (PWD). CASE REPORT: The patient had experienced PWD for 2 years, followed by other cognitive deficits suggestive of parietotemporal dysfunction. Brain imaging including (18)FDG-PET and [(11)C] PIB-PET supported the diagnosis of AD. CONCLUSIONS: Our case highlights the clinical variability that characterizes early-onset AD.

Language-specific dysgraphia in Korean stroke patients.

OBJECTIVES: We investigated how changes in the writing of 14 Korean stroke patients reflect the unique features of the Korean writing system. BACKGROUND: The Korean writing system, Han-geul, has both linguistic and visuospatial/constructive characteristics. In the visuospatial construction of a syllable, the component consonant(s) and vowel(s) must be arranged from top-to-bottom and/or left-to-right within the form of a square. This syllabic organization, unique to Korean writing, may distinguish dysgraphia in Korean patients from the disorder in other languages, and reveal the effects of stroke on visuospatial/constructive abilities. METHODS: We compared 2 groups of patients affected by stroke, 1 group with left hemisphere (LH) lesions and the other with right hemisphere (RH) lesions. We instructed them to write from a dictation of 90 monosyllabic stimuli, each presented with a real word cue. Patients had to repeat a target syllable and a word cue, and then to write the target syllable only. RESULTS: Patients with LH and RH lesions produced qualitatively different error patterns. While the LH lesion group produced primarily linguistic errors, visuospatial/constructive errors predominated in the group with RH lesions. With regard to language-specific features, these Korean patients with RH lesions produced diverse visuospatial/constructive errors not commonly observed in dysgraphia of the English language. CONCLUSIONS: Language-specific writing errors by Korean stroke patients reflect the unique characteristics of Korean writing, which include the arrangement of strokes and graphemes within a square syllabic form by dimensional and spatial rules. These findings support the notion that the Korean writing system possesses a language-specific nature with both linguistic and visuospatial/constructive processes. Distinctive patterns of dysgraphia in the Korean language also suggest interactivity between linguistic and visuospatial/constructive levels of processing. This study is noteworthy for its systematic description of Korean dysgraphia in the largest group of patients studied to date.

Is phonological-lexical representation preserved in moderate stage Alzheimer disease? Evidence from the efficacy of Korean syllabic cues.

Patients with Alzheimer disease (AD) usually experience naming difficulty due to storage and access problems in phonological-lexical representation. Investigating naming response patterns followed by cueing may help us to understand the underlying mechanism of naming deficits in AD. A total of 221 patients with mild cognitive impairment and AD [Clinical Dementia Rating (CDR) 0.5, 1, 2] were included as subjects. Sixty items of the Korean version of the Boston Naming Test were given, and upon failure, semantic/syllabic cues were verbally presented. From the results, even in the CDR 2 group, which is considered to be a moderate stage of AD, syllabic cues significantly facilitated correct responses. Our findings are in contrast with previous studies conducted with English-speaking patients, which reported that phonological-lexical representation may have been disrupted in the moderate stage of AD, and that none of the cues facilitated correct word retrieval. The difference may be ascribed to the fact that direct access to the phonological-lexical representation via syllabic cues was possible in the confrontation naming task performed by the Korean patients. It can be concluded that phonological-lexical representation in moderate stage Korean AD might be partially preserved because syllabic cues in AD patients were effective in facilitating target words.