J Neurogastroenterol Motil 2021; 27(4): 650-652  https://doi.org/10.5056/jnm21027
Cognitive Deficits Associated With Dysphagia in Patients With Dementia
Sun-Wung Hsieh,1,2,3,4,5 Hui-Yu Chuang,1 Chih-Hsing Hung,4,5,6,7,8 and Chun-Hung Chen1,2,3,4*
1Department of Neurology, Kaohsiung Municipal Siaogang Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; 2Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; 3Neuroscience Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan; 4Dysphagia Functional Reconstructive Center, Kaohsiung Municipal Siaogang Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; 5Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; 6Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; 7Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; and 8Department of Pediatrics, Kaohsiung Municipal Siaogang Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
Published online: October 30, 2021
© The Korean Society of Neurogastroenterology and Motility. All rights reserved.

cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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TO THE EDITOR: Dysphagia is very prevalent but often under-estimated among patients with dementia. Dysphagia leads to dehydration, impaired functionality, malnutrition, respiratory infections, reduced quality of life, and increased mortality, which complicates dementia.1 Dysphagia can occur in different types of dementia and can be shown during the whole course of dementia.2 Despite this, there are limited studies discussing the role of specific cognition deficits on dysphagia in patients with dementia. Herein, we aim to investigate the cognition associated with dysphagia in patients with dementia.

We recruited patients with dementia in our hospital. Dementia was diagnosed by using the “National Institute of Neurological Disorders and Stroke (NINCDS)-Alzheimer’s Disease and Related Disorders Association criteria.”3 We administered demographic data and psychometrics for the subjects, including Mini-mental State Examination (MMSE),4 Cognitive Abilities Screening Instrument (CASI),5 Clinical Dementia Rating (CDR)6 and CDR-sum of boxes (CDR-SB).6 CASI comprises 10 sub-scales as follows, remote memory, recent memory, attention, mentality, orientation, drawing, abstract, judgement, fluency, and language. We screened the swallowing function for subjects with dementia by using “Eating Assessment Tool-10 (EAT-10).”7 We recorded the summation of scores to indicate the severity of dysphagia. We presented the demographic data and difference of dysphagia variables between very mild to mild dementia (CDR 0.5 and 1) and moderate to severe dementia groups (CDR 2 and 3). We calculated the correlation between cognitive variables and dysphagia variables by Spearman’s correlation test.

After excluding 44 from a total of 89 subjects due to incomplete cognitive and dysphagia assessment, there were 45 subjects (25 female, 55.6 %) with dementia recruited in our study. The mean age was 76.9 years old and there were 32 (71.1%) with very mild to mild dementia. There were 19 subjects (42.2%) with high risk of dysphagia (EAT-10 ≥ 3). Table 1 demonstrates the demographic data and showed no difference of age, gender, and dysphagia between the 2 groups. Table 2 demonstrates the correlation of cognition with EAT-10. CDR-SB, MMSE, and CASI showed no correlation with EAT-10. Only attention sub-scale was correlated with EAT-10 (r = −0.302, P = 0.044).

Table 1 . Demographic Data and Difference of Cognition and Dysphagia Between Very Mild to Mild Dementia and Moderate to Severe Dementia Groups

Demographic dataTotal (N = 45)Very mild to mild dementia
(CDR 0.5, 1)
(n = 32)
Moderate to severe dementia
(CDR 2, 3)
(n = 13)
P-value
Age (yr)76.9 ± 9.077.8 ± 8.874.6 ± 9.20.278
Gender (female)25.0 (55.6)19.0 (59.4)6.0 (46.2)0.419
MMSE11.3 ± 6.413.5 ± 5.66.0 ± 5.1< 0.001
CASI38.5 ± 22.646.3 ± 18.519.5 ± 20.7< 0.001
CDR-SB6.9 ± 4.34.6 ± 2.312.4 ± 2.5< 0.001
EAT-104.6 ± 6.53.3 ± 4.88.1 ± 8.90.084
EAT-10 ≥ 319.0 (42.2)11.0 (34.4)8.0 (61.5)0.094

CDR, clinical dementia rating; MMSE, mini-mental state examination; CASI, cognitive abilities screening instrument; CDR-SB, clinical dementia rating-sum of boxes; EAT-10, eating assessment tool-10.

Values are presented as mean ± SD or n (%).

P < 0.05, statistically significant.



Table 2 . Correlation Between Cognition and Eating Assessment Tool-10

Correlation resultsEAT-10
Age (yr)
r0.069
P0.652
CDR-SB
r0.253
P0.093
MMSE
r−0.064
P0.675
CASI total score
r−0.054
P0.727
CASI sub-scales
Remote memory
r−0.123
P0.420
Recent memory
r0.040
P0.794
Attention
r−0.302
P0.044
Mentality
r−0.054
P0.723
Orientation
r−0.030
P0.844
Drawing
r−0.060
P0.694
Abstract
r−0.187
P0.218
Judgement
r−0.032
P0.836
Fluency
r−0.111
P0.468
Language
r−0.205
P0.177

CDR-SB, clinical dementia rating-sum of boxes; MMSE, mini-mental state examination; CASI, cognitive abilities screening instrument; EAT-10, eating assessment tool-10; r, correlation coefficient.

P < 0.05, statistically significant.



We concluded no correlation between dysphagia and severity of dementia. We only observed the attention deficit was associated with dysphagia in patients with dementia. Dysphagia may develop during any course of dementia. Attention deficit is found to be associated with the impaired frontal connectivity in patients with subcortical ischemic vascular dementia and Alzheimer’s disease.8 Saito et al9 speculated a neural circuit responsible for swallowing indicating that the middle frontal gyrus serves as an association area between the insula (as a sensory center) and the primary motor cortex (as a motor center). The lesion in the primary motor cortex may cause buccofacial apraxia (BFA) and limb kinetic apraxia, which presented frequently in patients with dementia. Although BFA is related with severity of dementia, Michel et al10 concluded no significant association between BFA and dysphagia. Researches indicated the prefrontal cortex, containing the large part of middle frontal gyrus, involved in swallowing function in the higher cognition level. The prefrontal cortex integrates perceived sensory signals with motor commands. Dorsolateral prefrontal cortex, locating in anterior half of the middle frontal gyrus, performs not only self-awareness and attentional control but also executive control of working memory.

Overall, we conclude that the attention deficit was associated with dysphagia in patients with dementia. Further studies focusing on evaluation of attention profiles and functional connectivity between frontal lobe and swallowing may aid in optimizing therapeutic approaches in dementia.

Financial support

This study was supported by Kaohsiung Municipal Siaogang Hospital, Kaohsiung, Taiwan (S-108-008, Kmhk-104-035, Kmhk-108-033, S-108-009, and S-109-001), and Kaohsiung Medical University Research Center Grant (KMU-TC109B03).

Conflicts of interest

None.

Author contributions

Sun-Wung Hsieh was involved in drafting the manuscript; Hui-Yu Chuang was involved in collecting data; Chih-Hsing Hung was involved in interpreting data; and Chun-Hung Chen was involved in the study design.

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