Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that primarily causes memory loss and cognitive decline due to the accumulation of misfolded proteins in the brain. This deterioration eventually impacts the ability to perform basic daily activities. A common fear among families is whether the disease can advance so far that a person simply “forgets” the automatic act of breathing. This article addresses that concern by examining the distinct neurological control systems for respiration and identifying the true respiratory danger in the later stages of the disease.
How the Brain Controls Automatic Breathing
The human brain uses two separate systems to manage respiration: one for voluntary control and one for involuntary control. Voluntary breathing, such as holding your breath or taking a deep sigh, is managed by the cerebral cortex. This area of the brain is most heavily damaged by the plaques and tangles of Alzheimer’s disease. As AD progresses, the patient loses the ability to consciously control many actions, including intentional manipulation of their breath.
The automatic, life-sustaining rhythm of breathing, however, is regulated by a more primitive structure known as the brainstem, which includes the pons and the medulla oblongata. This region contains the central pattern generator for breathing, which fires rhythmically without requiring any conscious input. These brainstem nuclei also contain chemoreceptors that constantly monitor the blood’s carbon dioxide levels, automatically adjusting the breathing rate to maintain stable body chemistry.
The pathology of Alzheimer’s disease typically affects the cerebral cortex and hippocampus long before it severely impacts the brainstem nuclei responsible for the respiratory drive. For this reason, the autonomic function of breathing remains a remarkably preserved, almost fail-safe mechanism, well into the late stages of the disease.
Why Aspiration Pneumonia Is the Real Danger
While the neurological failure to initiate breathing is rare, a different, mechanical failure related to the respiratory system becomes the most significant risk in advanced Alzheimer’s disease. The cognitive and motor decline associated with the disease eventually leads to dysphagia, which is the medical term for difficulty swallowing.
This impaired coordination means that food, liquid, or even saliva may not be correctly routed into the esophagus, instead entering the trachea, or windpipe. This event is known as aspiration. Aspiration is frequently compounded by a reduced or absent cough and gag reflex, which are the body’s last lines of defense against foreign material entering the lungs.
Aspiration pneumonia occurs when this foreign material, often carrying bacteria from the mouth, causes an infection in the lungs. This infection is cited as the most common immediate cause of death in people with end-stage Alzheimer’s disease. The risk is further increased by poor oral hygiene, as a higher load of bacteria in the mouth means more pathogens are introduced into the lungs during an aspiration event.
Supporting Respiratory Health in Late-Stage Alzheimer’s
Caregiver efforts in late-stage Alzheimer’s must focus on mitigating the risk of aspiration pneumonia, since the automatic breathing function remains intact. One of the most important preventative steps involves monitoring for signs of dysphagia, such as persistent coughing during meals, a gurgly voice after swallowing, or food “pocketing” in the cheeks. Adapting the consistency of foods and liquids, often by using commercial thickeners, can make swallowing safer by slowing the flow of liquids.
Proper positioning is also a simple yet effective physical intervention. This requires the individual to be seated upright at a 90-degree angle during all feeding times and remaining upright for at least 30 minutes afterward. This posture uses gravity to encourage the correct passage of food down the esophagus.
Another protective measure is maintaining meticulous oral hygiene, which reduces the bacterial load in the mouth and therefore minimizes the number of pathogens that could be aspirated into the lungs. Regular vaccination against influenza and pneumococcal pneumonia is a foundational step in reducing the risk of respiratory infection. Ultimately, as the disease progresses and swallowing difficulties become more pronounced, the focus shifts to comfort and dignity, often involving the guidance of palliative or hospice care teams.