Oropharyngeal dysphagia in elderly population suffering from mild cognitive impairment and mild dementia: Understanding the link

Abstract

Purpose

To evaluate the prevalence of oropharyngeal dysphagia in elderly patients suffering from minimal or mild cognitive decline.

Patients and methods

We retrospectively collected the data of patients suffering from mild cognitive impairment or mild dementia and were undergoing management for suspected oropharyngeal dysphagia, in our department. All our patients were subjected to Mini Mental State Examination test, MD Anderson dysphagia inventory and caregiver mealtime and dysphagia questionnaire. We performed a mealtime observation study and endoscopic evaluation of swallowing in all our patients. Following evaluation, we then analysed the data statistically.

Results

Out of 708 patients who visited us for cognitive decline and suspected oropharyngeal dysphagia in the last two years, 52 patients were confirming to the inclusion criteria of this study.

Classification of oropharyngeal dysphagia patients according to ASHA-NOMS scale showed that 32.7% of patients presented with grade 4 of dysphagia followed by another 32.7% with grade 5 and 30.8% presented with grade 6. Only 3.8% of our patients were considered normal (grade 7 of ASHA-NOMS scale). MD Anderson dysphagia inventory could collected swallowing alterations in only 23.1% of the cases. The caregiver mealtime and dysphagia questionnaire showed acceptable caregivers patient management in 53.8% of patients.

Conclusion

Our study underscores the fact that oropharyngeal dysphagia is present in many cases of mild cognitive decline. While patients understate their swallowing problems, the caregivers are not competent enough to manage this situation in a great percentage of cases. Only a mealtime observation by a speech-language pathologist along with FEES is able to identify the true prevalence of the condition.

Introduction

Measurable changes in cognition occur with normal ageing. The most important changes are declines in cognitive tasks that require one to quickly process or transform information such as in making a decision, including in measures of speed of processing, working memory, and executive cognitive function [1].

Ageing is associated with a slowing of the swallow response in the pharynx due to both central and peripheral factors. These changes may have an impact on the movement of food bolus. It is well described in the literature that tongue pressure declines with age [2]. Lack of muscle strength complicated by the decline in sensory informations such as olfaction and taste and/or by a poor dental status observed in the elderly makes swallowing more difficult. This scenario is known as presbyphagia and is more commonly seen after the age of 80 [2]. Presbyphagia, in itself, does not give rise to pathological changes in swallowing but it is a risk factor that can lead to Oropharyngeal Dysphagia (OD) [3]. In fact, the prevalence of OD has been calculated in independently living elderly persons with rates between 30% and 40%, 44% in those admitted to geriatric acute care and 60% in institutionalised elderly patients [[4], [5], [6]]. Unfortunately, in a presbyphagic scenario, patients affected by dementia easily develop OD during the course of their disease.

Generally, swallowing impairment in Alzheimer's and other forms of dementia is well described for the severe or moderate stages of the diseases [7]. While in the earlier stages it is often underdiagnosed [8]. Dysphagia related to Alzheimer's dementia (AD) is caused by involvement of the cortical areas of the brain for swallowing and due to the presence of delayed swallowing reflex and oropharyngeal problems. Recently, in 2019, Oszurecki reported this in the early stage of disease too [8].

In other forms of severe dementia, OD is caused by various other alterations in the brain. For example, Suh et al. in 2009 reported, that, Vascular Dementia (VAD) patients showed either multiple strokes or periventricular white matter involvement of portions of the brain sometimes which may even be in a single strategic area. (9 Suh). These alterations can lead to motor impairment in swallowing resulting in dysphagia with difficulties in mastication and bolus formation [9].

In addition, in cases of Fronto Temporal Dementia (FTD), it is described that hypothalamic degeneration with the disintegration of connections between the hypothalamus and the orbitofrontal cortex/reward pathways is what causes eating abnormalities.

In subjects suffering from Primary Progressive Aphasia (PPA) presence of high levels of the eating peptides and overall Agouti-related-peptide (AgRP) is observed. Agouti-related-peptide is a strong promoter of food intake [10]. These alterations cause changes in eating habits, hyperorality and disinhibition during the meal [10]. Langmore in 2007 while analysing swallowing behaviours in patients suffering from FTD and PPA showed that these patients presented with compulsive eating behaviours often associated with minimal endoscopic signs of OD. This association favoured an increased risk of aspiration too [11].

Interestingly, the patients who are suffering from Mild Cognitive Impairment (MCI) with seemingly good swallowing or chewing ability, as perceived by their own caregivers [12], also had impairment of oral diadokokinesis and spilling of food. This is caused mainly by impaired oral motor skills such as poor lip function and has been well described for this class of patients [13]. In addition, Delwel reported that MCI patients evaluated in his study showed a limited active maximum mouth opening (<40 mm) [12] and this fact can play a pathological role in swallowing or chewing.

The purpose of our study was to evaluate whether OD is already present in elderly patients suffering from mild or very slight cognitive decline and if this was related to further risk, even fatal, for the patient.