Dementia is more than memory loss, and rare types can affect vision, movement, and behavior. Recognizing these symptoms early can improve diagnosis and support.
When most people hear the word “dementia,” they think of memory loss and forgetfulness. But dementia can affect far more than memory, causing changes in speech, behavior, sleep, movement, and other functions.
Dementia is not a single disease but a broad term that includes more than 100 different conditions. Alzheimer’s disease is the most common form, accounting for about 60% of cases, and memory problems are among its best-known symptoms.
The remaining 40% of dementia cases involve rarer forms that are often harder to diagnose and may require more specialized care. While many people are familiar with conditions such as Lewy body dementia, Parkinson’s disease dementia, and frontotemporal dementia, awareness of other uncommon forms remains limited.
Recognizing the warning signs of these lesser-known dementias early may help people receive the care and support they need sooner.
Posterior cortical atrophy
Posterior cortical atrophy (PCA) affects mostly visual and spatial functioning. Memory is not as badly affected early on as it is in Alzheimer’s disease.
People with PCA can struggle with visual hallucinations and spatial navigation. This can become apparent when reading or judging depth and space on a staircase, making it difficult to judge where the next step is, for example. Symptoms commonly start appearing between the ages of 55 and 65.
There’s still much we don’t know about PCA because of how rare it is. Researchers are still trying to figure out whether PCA is a distinct subtype of dementia or whether it’s an atypical form of Alzheimer’s disease. This is because the brain changes that occur in people with PCA closely resemble those that occur in people with Alzheimer’s disease, although the symptoms are different. It’s also estimated that between 5% to 15% of people with Alzheimer’s have PCA.
Creutzfeldt-Jakob disease
Creutzfelt-Jakob disease is a particularly rare form of dementia, affecting about one in 1 million people worldwide.
Creutzfeldt-Jakob disease is a prion disease. These diseases involve prion proteins, which, for unknown reasons, suddenly change into a three-dimensional shape. The function of healthy prions remains unknown, but they appear to play some role in protecting nerves and brain cells and keeping the body’s circadian rhythm functioning (the natural, 24-hour cycle our body follows that controls everything from sleep, digestion, and immunity).
The misfolding of prion proteins in Creutzfeldt-Jakob disease causes a very rapid and severe form of dementia, progressing much more quickly than Alzheimer’s disease or Lewy body dementia, for example. Besides the notably quick nature of progression, people with Creutzfeldt-Jakob disease struggle with memory and movement, including sudden jerky movements.
Risk factors for this subtype of dementia include old age and genetics (occurring in 10-15% of cases). In very rare cases, it can also develop as a result of contamination–such as from eating beef from cattle infected with mad cow disease.
FTD-MND
FTD-MND is a form of frontotemporal dementia that occurs alongside motor neuron disease.
Frontotemporal dementia refers to subtypes of the disease that cause gradual brain tissue loss in the frontal and temporal lobes of the brain.
Motor neuron disease, on the other hand, is a rapidly progressing neurological condition which can lead to difficulties breathing, movement, and paralysis. Although it affects the brain and nerves, it is not itself a form of dementia.
Approximately 10-15% of people with frontotemporal dementia also develop motor neuron disease. This co-occurrence seems to be linked to a mutation in the C9orf72 gene. Because of this genetic link, FTD-MND can run in families.
People with FTD-MND experience several muscle-related issues, including muscle wasting, stiffness, and problems with swallowing. These are things you would not normally associate with dementia and memory problems.
It’s currently not clear whether frontotemporal dementia develops first and then motor neuron disease or if it’s the other way around.
Progressive supranuclear palsy
Progressive supranuclear palsy (PSP) is a rare neurological condition that causes both dementia and problems with movement.
It’s estimated to affect approximately 4,000 people in the UK. PSP is difficult to diagnose as it overlaps with many other conditions, including Parkinson’s disease.
PSP primarily leads to damage in subcortical brain regions, specifically the brainstem and basal ganglia. These areas are linked to vision and movement.
As such, people with PSP struggle using their eyes and can thus often fall and experience difficulties moving around. People with PSP can also struggle with concentrating and problem-solving.
Dementia support
As with all dementia subtypes, there is no cure yet. While there are medications that can delay symptoms, these only work in cases of Alzheimer’s disease.
As such, we still need to find ways to support people with other subtypes of dementia as best as possible.
One way of doing this is by properly understanding their condition and their subtype. Knowing that someone might particularly struggle with walking and movement as opposed to memory is important to put the right care in place in advance.
It is just as important to be able to spot the signs early on. Dementia doesn’t just affect memory. Changes in behavior, problems seeing or falling more frequently, walking or moving differently, or difficulty speaking can all be early signs of dementia.
Better understanding dementia’s many forms will hopefully lead to better ways of managing and treating this complex disease.
Adapted from an article originally published in The Conversation.
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