Early Deficits in Cortical Control of Swallowing in Alzheimer's Disease

Abstract

The goal of this study was to determine whether functional changes in cortical control of swallowing are evident in early Alzheimer's disease (AD), before dysphagia (swallowing impairment) is evident. Cortical function was compared between an early AD group and a group of age-matched controls during swallowing. Swallowing oropharyngeal biomechanics examined from videofluoroscopic recordings were also obtained to more comprehensively characterize changes in swallowing associated with early AD. Our neuroimaging results show that the AD group had significantly lower BOLD response in many cortical areas that are traditionally involved in normal swallowing (i.e. pre and postcentral gyri, Rolandic and frontal opercula). There were no regions where the AD group recruited more brain activity than the healthy controls during swallowing and only 13% of all active voxels were unique to the AD group, even at this early stage. This suggests that the AD group is not recruiting new regions, nor are they compensating within regions that are active during swallowing. In videofluoroscopic measures, the AD group had significantly reduced hyo-laryngeal elevation than the controls. Although, swallowing impairment is usually noted in the late stages of AD, changes in cortical control of swallowing may begin long before dysphagia becomes apparent.

Características de mastigação e deglutição na doença de Alzheimer

“…Foi detectada tendência a aspiração proporcional ao grau de demência 43 . Ao investigar as funções relacionadas a alimentação e deglutição de idosos entre 70 e 91 anos com demência, a maioria dos indivíduos pesquisados apresentou dificuldades relacionadas ao momento da alimentação, como: inabilidade no preparo do alimento, manuseio de utensílios, na higiene oral, além de dependência em relação ao cuidador 39 .…”

“…O envelhecimento e suas consequências, cirurgias de cabeça e pescoço, depressão, demência, uso de fármacos, particularmente em idosos, também favorecem a aspiração silenciosa 42 . Diversos trabalhos relatam que as alterações da deglutição estão associadas com ao grau da demência 1,10,39,43 . Na avaliação da deglutição realizada em estudo com idosos, os indivíduos conseguiam compensar algumas alterações encontradas nas fases oral e faríngea da deglutição, como deglutição lentificada, deglutindo repetidas vezes até a limpeza total 39 .…”

Ressonância magnética funcional e deglutição: revisão sistemática

“…A chronological analysis of the presented studies, observed that initially the concern was the confirmation of cortical activation mechanisms for swallowing Therefore, procedures such as saliva (1,3,5,7,(16)(17)(18)(19)(20)22,23,26,(29)(30)(31)(32) , water (5,11,12,17,(24)(25)(26)28,29,31) , barium (5,26,29,31) swallowing were performed, comparing swallow and not swallow (1,7,14,27) . Later on, studies began to analyze differences in the cortical areas, responsible for each motor phase, differentiating the role of the structures involved.…”

“…Even on population with dysphagia, they used swallowing of different types of food, such as water (5,(29)(30)(31) , barium (5,29,31) and saliva (5,(29)(30)(31)(32) . In the case of food introduction, they were generally administered by positioning a catheter in different portions of the oral treatment, varying in time and food volume administration.…”

“…There was a tendency to use healthy adults for comparison with elderly people (1,26,27) , except in two researches (5,28) . Studies involving dysphagia patients groups or patients with specific diseases were compared with those who evaluated healthy individuals, matched by chronological age and elderly patients (6,(29)(30)(31)(32) .…”