Which Sense is Most Affected by Alzheimer’s Disease
Which Sense is Most Affected by Alzheimer’s Disease
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Alzheimer’s disease is a progressive neurological disorder that gradually destroys memory and cognitive functions.
As the disease progresses, it affects multiple areas of the brain that control not only thinking and memory but also basic bodily functions and senses.
The five traditional senses – sight, smell, taste, touch, and hearing – play an important role in how we perceive and interact with the world.
For Alzheimer’s patients, impairment or loss of senses adds another layer of difficulty as they navigate daily life.
Some senses seem to be more susceptible to deterioration than others. Research has provided clues as to which sensory systems may be attacked most severely by the pathological changes of Alzheimer’s disease.
This article examines current evidence on how Alzheimer’s impacts each of the five senses, and which sense seems to be affected the most.
Understanding how the different senses are impacted can help caregivers provide better support to patients as the disease advances.
But first, let’s understand some basics about Alzheimer’s disease.
What is Alzheimer’s Disease?
Alzheimer’s disease, a progressive neurodegenerative disorder, is the most common cause of dementia among older adults. It gradually erodes cognitive function, impacting memory, thinking, and behavior.
Named after Dr. Alois Alzheimer, who first described the condition in 1906, the disease primarily affects individuals aged 65 and older.
However, early-onset Alzheimer’s can manifest in individuals in their 40s or 50s.
The disease involves an accumulation of abnormal deposits of beta-amyloid protein forming plaques and twisted strands of tau protein forming tangles inside brain cells.
Over time, these deposits damage surrounding neurons and synapses in areas involved with learning, memory, and cognition, leading to the death of brain cells and the loss of brain tissue.
Loss of brain volume and neuronal death eventually lead to an inability to communicate and complete basic activities of daily living.
As Alzheimer’s progresses, symptoms will significantly worsen.
In the final stages, individuals may be unaware of family/friends and need round-the-clock assistance with basic tasks.
While Alzheimer’s is widely believed to stem from a complex interplay of genetic, lifestyle, and environmental factors, the exact mechanisms through which it develops are still under research.
Common Signs and Symptoms of Alzheimer’s Disease
Memory loss that affects daily life
Challenges in planning or solving problems
Difficulty completing familiar tasks
Confusion with time or place
Trouble understanding visual images and spatial relationships
New problems with words in speaking or writing
Misplacing things and losing the ability to retrace steps
In Alzheimer’s patients, changes in hearing can manifest in two main ways.
Some individuals may start experiencing a clinical decline in their ability to hear certain sounds and volume levels.
However, others may retain excellent hearing ability while still struggling to process and interpret sounds accurately.
This reveals a key aspect of how Alzheimer’s impacts the sense of hearing – it is not just about the reception of sound inputs, but the brain’s capacity for sound processing and comprehension.
Even in the early stages, individuals may have difficulties following conversations, especially in noisy environments.
As the disease progresses further, patients often lose the ability to recognize speech patterns, identify familiar voices, or discriminate between tones and pitches.
This can significantly hinder communication and reduce quality of life if hearing aids or other assistive strategies are not provided.
Additionally, Alzheimer’s patients tend to get overstimulated easily by loud or numerous sounds.
As author Mirian Green notes about her mother’s experience with dementia in her book, even normal background noises like passing vehicles or voices that others filter out easily could completely overwhelm her mother and cause her to withdraw.
How to help:
Create a calm living environment and reduce background noise to minimize auditory overstimulation.
Speak slowly and calmly when communicating. Encourage clear communication from friends and family to facilitate better understanding and reduce confusion.
Avoid concurrent exposure to multiple sources of noise, such as having the television and radio on simultaneously.
Prioritize regular hearing checkups to promptly address emerging hearing issues. Early detection and intervention contribute to the effective management of hearing challenges.
4. Alzheimer’s and Sense of Sight
While the eyes themselves typically remain intact in Alzheimer’s disease, changes in the brain can disrupt how visual information is processed and perceived.
Patients’ depth perception and sense of spatial relationships may become altered due to neurodegeneration.
For example, rather than comprehending a set of black and white tiles as a patterned floor, it could incorrectly appear as dangerous holes.
This impaired visual processing raises safety concerns as individuals may misjudge distances, levels, or sense of movement.
Other common sight-related difficulties include an inability to recognize familiar faces or objects.
As the disease advances, a loved one may struggle to identify what or who is directly in front of them.
Simple visual tasks like finding an object within their field of view or navigating spaces can become challenging without cues.
These visual cognitive deficits have meaningful implications for day-to-day activities and quality of life.
Impairments in orientation and judging physical relationships in the environment increase risks for accidents, wandering, or other issues.
How to help:
Contrasting colors on doors, drawers, and fixtures like cabinets can aid navigation and identification of important rooms and items.
Solid, differentiated wall and floor colors limit visual confusion compared to patterned designs.
Picture cues on bathroom and bedroom doors also help orientation.
Color-contrast safety strips running edge-to-edge on level changes are also a direct solution to issues with depth perception placing the person at risk for falls.
5. Alzheimer’s and Sense of Touch
As Alzheimer’s pathology progresses throughout the body, the ability to perceive touch sensations typically deteriorates.
Patients may lose sensitivity to heat, cold, discomfort, or pain – a profound change that impacts everyday experiences and safety.
Touch plays a key role in forming feelings of security, connectedness, and well-being.
So declining tactile sensation can contribute to a sense of detachment and isolation for someone with advanced dementia.
How to help?:
Clearly label hot and cold on sinks to avoid accidental scalds. Use visual cues near appliances like ovens once hot.
Check food temperatures yourself as the person may not feel if something is too hot/cold.
Provide soft, textured comfort items that can still be appreciated through touch like blankets and stuffed toys.
Gentle physical contact like holding hands, hugs, or shoulder rubs can be a meaningful way to communicate caring through the language of touch that is still relatable.
Which Sense Does Alzheimer’s Affect the Most?
While sensory changes vary between individuals, the sense of smell (olfaction) may be most significantly impacted by Alzheimer’s disease pathology.
Individuals with normal cognition but low odor ID scores were more likely to later develop mild cognitive impairment compared to those with better smell function.
Among those with amnestic mild cognitive impairment, impaired olfaction predicted future conversion to full Alzheimer’s dementia.
Odor identification has also correlated strongly with other objective biomarkers of Alzheimer’s disease.
Hearing loss is another sensory deficit common in Alzheimer’s. Previous research demonstrates associations between the degree of hearing impairment and the incidence of cognitive decline.
Hearing problems independently increase the risk for all-cause dementia.
More research continues to enhance understanding of how specific sensory abilities deteriorate at different disease stages and which may serve as the most useful diagnostic and prognostic markers.
Why is the Treatment of Sensory Problems Important?
Sensory impairments are important to treat in Alzheimer’s patients as they can accelerate cognitive decline if left unaddressed.
Problems with vision, hearing, and other senses have been identified as risk factors for dementia according to research.
For example, one study estimated that nearly 100,000 dementia cases in the US could have been prevented if existing vision treatments were used, highlighting the role of visual impairment as a risk factor.
When older adults experience untreated vision loss, they often stop driving, going out in the community, reading, and engaging in physical exercise due to fear of falling.
This reduces social interaction, and emotional well-being, and leads to physical inactivity – factors that are themselves linked to a greater risk of cognitive decline.
Similarly, untreated hearing loss prompts social withdrawal as older adults try to avoid uncomfortable interactions where they struggle to engage in conversations during their daily activities.
Sensory stimulation is important for maintaining functions like sound processing over time, and this social isolation and lack of stimulation may lead to shrinkage of sound processing areas of the brain.
This five-year clinical trial is tracking nearly 1,000 older adults with hearing loss to compare cognitive outcomes between those treating their hearing loss and control groups who are not.
In essence, regardless of the specific sensory impairment one may be facing, prompt treatment is highly important.
Not treating impairments removes opportunities for sensory enrichment that may help preserve brain plasticity and function even in the face of disorders like Alzheimer’s.
In summary, Alzheimer’s disease impacts all senses in one way or another, however, the degree to which each is compromised varies significantly between individuals.
While vision, taste, and touch may also deteriorate to varying extents, olfactory dysfunction currently shows the greatest potential as a sensitive early biomarker for emerging Alzheimer’s pathology.
Nonetheless, all sensory changes can reduce the quality of life for patients and increase safety risks if not addressed, which is why treatment is very important to slow cognitive changes and preserve brain functions.
Maximizing sensory enrichment through low-cost adaptations to the environment can also help optimize the independence of Alzheimer’s patients.
1. Can sensory problems be an early sign of Alzheimer’s disease?
Yes, sensory problems, particularly changes in vision, hearing, and smell, can serve as early indicators of Alzheimer’s disease. These alterations may precede more overt cognitive symptoms and warrant attention for early detection and intervention.
2. How does sensory impairment impact the daily life of individuals with Alzheimer’s?
Sensory impairment in Alzheimer’s can lead to challenges in communication, safety concerns, and reduced engagement in daily activities. For example, vision changes may affect navigation, while hearing loss can contribute to social isolation.
3. How can caregivers help individuals with Alzheimer’s cope with sensory challenges?
Caregivers can create a supportive environment by minimizing unnecessary stimuli, using visual cues, and encouraging the use of aids like hearing devices. Additionally, understanding the individual’s specific sensory needs and preferences is vital for providing personalized care.