Dementia, Alzheimer’s, and Visual Perception

According to the National Institute on Aging (NIA), the most diagnosed form of dementia is Alzheimer’s disease (Alzheimer’s and dementia | National Institute on Aging (nih.gov)). NIA states lifestyle and environmental factors combine and impact the start and progression of Alzheimer’s. Five factors to consider are age, family history, lifestyle such as social isolation, diet and exercise, medical conditions such as heart disease and blood pressure, and biomarkers. Variants in the apolipoprotein E (APOE) gene are an example of biomarkers (Thinking About Your Risk for Alzheimer’s Disease? Five Questions To Consider | National Institute on Aging (nih.gov). Research into all of these factors is still underway. 

Ten Early Warning Signs of Dementia 

VisionAware Peer Advisor Sandra Burgess, MSW, whose mother had dementia, put together this helpful list of warning signs: 

• Forgetting new information (important dates, events)—This was very common with my mom, who would call to make a doctor’s appointment, repeat the information out loud, and not remember when she went to another room to write it down.  
• Performing familiar tasks takes longer or cannot be completed without mistakes (writing checks, following a recipe, remembering how to drive to a familiar place) 
• Difficulty with where they are in time or place—Mom did not know the correct year or where she was living when she moved to a nursing home. 
• Problems with spatial relationships and visual images—Reading and determining distances, color, or contrast may be hard. Mom thought she was positioned to sit on a chair and ended up on the floor. 
• Demonstrating problems with words when speaking or writing and participating in a conversation 
• Misplacing items and being unable to retrace their footsteps 
• Showing changes in judgment and making poor decisions when dealing with money 
• Paying less attention to personal cleanliness 
• Withdrawing from hobbies, work projects, and social activities 
• Changes in mood or personality, such as getting upset or angry in uncomfortable situations 

Understanding Vision and Perception Problems

by Audrey Demmitt, R.N. 

People with dementia can have difficulties with vision and perception — causing them to misinterpret the world. The process of seeing is complicated, and there are many points at which things can go wrong. Disturbances in vision and perception can cause behavioral challenges and even safety risks. Caregivers who understand this can better support their loved ones and modify their physical environment so they can remain home longer. 

The Eyes and Brain Work Together 

Alzheimer’s is a disease of the brain. First, information is transmitted from the eyes to the brain, where it is interpreted. Other senses, thoughts, and memories contribute information that influences the interpretation and perception. These visual perceptions can be inaccurate or faulty depending on the function of the eyes and the diseased brain area. 

Five Main Visual Deficits Occurring in Alzheimer’s 

• Reduced ability to detect motion—Some people perceive the world as a series of still photos rather than an ongoing video like most people see. As a result, they may get lost, even in familiar surroundings. Following a moving object can be difficult and impacts the ability to watch television or comfortably do any activity involving fast motion. 
• Loss of depth perception—Individuals may have difficulty judging distances and elevation changes or distinguishing between a three-dimensional object and a flat picture. 
• Reduced peripheral vision—The field of vision often narrows with age. However, Alzheimer’s may cause dramatic narrowing, resulting in the inability to see to either side when gazing forward, disorientation, and a tendency to bump into things. 
• Color perception—Though colors often diminish with age, persons with Alzheimer’s may have a more significant deficit and difficulty recognizing colors, especially in the blue-violet range. Coordinating clothing may be a problem. 
• Contrast sensitivity—Detecting gradients of color is also reduced in persons with Alzheimer’s. They will have trouble picking out objects surrounded by similar colors. For example, a person may have difficulty finding the toilet in a bathroom where the floor, walls, and toilet are all white. 

Problems with Object and Facial Recognition 

Alzheimer’s can cause problems with recognizing objects and faces, causing an inability to name what is seen. 

Common Visual Perception Mistakes 

• Illusions or a “distortion of reality”—The distortion may result from a characteristic of the object. A shiny floor may be perceived as wet, or a face may appear in a patterned curtain. 
• Misperceptions—What the person sees is a “best guess” at the inaccurate or distorted information the brain receives from the eyes. The misperception is usually the result of damage to the visual system from diseases like cataracts or glaucoma. For example, a shadow on the carpet could be mistaken for a hole in the floor. Likewise, reflections in a mirror can be mistaken for an intruder. 
• Misidentifications—Damage to specific parts of the brain can lead to problems identifying objects and people. For example, distinguishing between a son, husband, or brother may become difficult. A green pillow may be interpreted to be a cabbage. 
• Problems with daily activities—Perceptual mistakes can lead to problems reading and writing, watching TV, moving around the home, using the bathroom, or saying or doing strange things that make others think they are having delusions. What the person is experiencing is not a delusion; delusions are based on incorrect reasoning or “delusional thinking.” These mistakes result from damage to the visual process involving the eyes and brain. 

Hallucinations and Delusions 

People with Alzheimer’s can experience hallucinations and delusions that are different from visuoperceptual mistakes (a component of visual perception that enables recognition of objects based on their form, pattern, and color). A visual hallucination involves perceiving or seeing something that is not there in the real world. Visual hallucinations can be as simple as seeing flashing lights or as complex as seeing animals or people. Hallucinations are imagined sensory experiences and can involve a combination of the senses —  what a person sees, smells, hears, tastes, or feels. 

Another condition that can cause hallucinations in people who are blind or low vision is Charles Bonnet Syndrome. This type of hallucination is solely visual and explained as a mirage or “phantom vision” of sorts. It usually occurs in older adults who are mentally healthy. However, sometimes consultation with a neurologist or other specialist is necessary to rule out any serious disorders that may mimic Charles Bonnet syndrome [such as migraine, epilepsy, brain tumors, dementia, Parkinson’s disease, or mental illness, for example]. For most patients, however, just knowing that they aren’t developing a mental illness and that the symptoms will eventually subside is all the treatment they need.  

Unlike a hallucination, a delusion involves a set of false beliefs. An Alzheimer’s patient with delusions may become suspicious of the people around them, believing that caregivers are trying to trick them or steal from them. Delusions are based on incorrect reasoning or “delusional thinking.” Memory loss and cognitive changes create confusion and can contribute to irrational beliefs. 

Effect of Medications on Cognitive Faculties 

According to Alzheimer’s Science News Summer 2023, several medications can mimic dementia: 

• Anxiety and Insomnia medications such as Ativan, Xanax, and Restoril 
• Chemotherapy drugs which can cause “chemo” brain 
• Pain medications, especially opioids that can affect short-term memory, fortunately usually reversible when discontinued 
• Corticosteroids such as prednisone  
• Statins that lower cholesterol may affect memory, but the research is not clearcut 
• Anticholinergic drugs, whose purpose is blocking the neurotransmitter acetylcholine, can cause confusion, memory problems, and sometimes delirium, among other effects. 
• Taking multiple medications can result in drug interactions 

Overall, the aging of kidneys and the liver can lead to the body’s inability to manage the effects of drugs, possibly leading to cognitive issues. 

Learn More 

Tips for Living Alone With Early-Stage Dementia | National Institute on Aging (nih.gov) 

Preventing Alzheimer’s Disease: What Do We Know? | National Institute on Aging (nih.gov) 

Dementia Video: Changes in Vision