When most people think of dementia, a specific image comes to mind.
The condition, which affects 7 million Americans, is primarily defined by memory issues, forgetfulness and gradual changes in personality.
Alzheimer’s disease, the most common form of dementia, makes up 60 percent of cases.
Other forms that have gained attention in the past several years include frontotemporal dementia, suffered by actor Bruce Willis, Lewy Body dementia and vascular dementia.
However, dementia is an umbrella term referring to more than 100 subtypes, which do not always cause stereotypical memory loss and can be more difficult to diagnose.
Creutzfeldt-Jakob disease (CJD), for example, while extremely rare, has a 100 percent fatality rate and kills within just a few months. Though memory loss does gradually occur, patients first may notice balance issues and involuntary jerking movements.
And about 15 percent of people with frontotemporal dementia may also go on to develop the fatal brain disease ALS.
Below are four of the dementia subtypes that fly under the radar and the signs to watch out for.
Posterior cortical atrophy
Posterior cortical atrophy (PCA), also known as Benson’s syndrome, is a type of dementia characterized by the degeneration of the brain’s outermost, wrinkled layer of gray matter.
This layer, called the cerebral cortex, controls high-level functions like consciousness, thought, emotion, memory, language and sensory processing.
Damage to the cerebral cortex can lead to severe visual processing issues, such as reading difficulties and poor depth perception, rather than early memory lapses. Other symptoms include trouble recognizing familiar objects and faces, blurred vision, navigation troubles and problems finding items around the house.
As PCA progresses, patients may experience anxiety, trouble with basic math, hallucinations and memory issues.
Researchers are still unsure if PCA is its own form of dementia or a variant of Alzheimer’s disease, as the disease often causes plaques of toxic amyloid proteins, similar to Alzheimer’s, but in the cerebral cortex instead of the hippocampus.
While Alzheimer’s is most common after age 65, PCA usually strikes between ages 50 and 65.
Because there is no specific diagnostic criteria for PCA, it’s unclear how many people have the condition, according to the Alzheimer’s Association. Some studies have estimated that PCA affects five percent of people with Alzheimer’s, but because it is often unrecognized, the Alzheimer’s Association notes the true figure could be 15 percent.
The causes of PCA are unknown, and there are no known genetic mutations associated with it. There are no treatments designed for PCA.
Creutzfeldt-Jakob disease
In rare cases, Creutzfeldt-Jakob disease can be caused by eating contaminated meat from animals such as deer that have been infected with chronic wasting disease (CWD). Pictured is a deer showing signs of CWD
Creutzfeldt-Jakob disease (CJD) is a rare form of dementia affecting 350 to 500 Americans every year or one in 1 million people worldwide.
The disease is caused when proteins called prions, for unknown reasons, do not fold correctly. Instead, they morph into three-dimensional shapes and pile up in the brain, leading to the rapid development of dementia.
Symptoms include quickly worsening confusion, disorientation, memory loss and poor judgment, as well as balance issues, stiff movements, involuntary jerking and twitching.
Patients may also experience blurred vision, depression, anxiety, slurred speech and insomnia.
CJD is always fatal. While typical dementia usually takes years to kill a patient, CJD only takes a few months to a year.
Patients typically die of other issues associated with the disease such as trouble swallowing, heart and lung failure or pneumonia.
In extremely rare cases, CJD has been linked to eating meat from animals with chronic wasting disease, but about 85 percent of cases are random and have no known cause.
Because most cases are sporadic, it’s difficult for experts to determine specific risk factors, but being over 60, having a family history of CJD or being exposed to contaminated tissue, such as through a transplant, may be more likely to develop the condition.
FTD-MND
Bruce Willis (left) was diagnosed with frontotemporal dementia in 2023. Eric Dane (right) died of ALS earlier this year at age 53
FTD-MND is a form of frontotemporal dementia that occurs alongside motor neuron disease (MND), known as ALS or Lou Gehrig’s disease in the US.
Frontotemporal dementia (FTD) is a form of dementia that causes a gradual decline in the areas of the brain linked to personality and language abilities. Both actor Bruce Willis and talk show host Wendy Williams have been diagnosed with the disease.
FTD eats away at the parts of the brain that control language, behavior and personality. Unlike Alzheimer’s disease, patients don’t lose their memory immediately but instead undergo personality changes.
It also attacks areas of the brain responsible for judgment, impulse control and decision-making, leaving patients vulnerable to mismanaging their finances.
FTD accounts for about one in 20 dementia cases, adding up to roughly 50,000 to 60,000 Americans.
Experts estimate about 10 to 15 percent of people with FTD also develop ALS, which has been linked to a mutation in the C9orf72 gene, so FTD-MND can run in families. It’s unclear if FTD or ALS develops first.
ALS is not a form of dementia but is a rapidly progressing and terminal disease that attacks neurons in the brain and spinal cord responsible for motor functions.
ALS affects about 30,000 Americans and kills in just two to five years as the neuron damage attacks the body’s ability to move, eat and breathe. Symptoms include muscle weakness, twitching, cramping, stiffness, speech difficulties, trouble swallowing and gradual paralysis.
About 5,000 die every year. Actor Eric Dane died of the condition earlier this year at just 53 years old.
Progressive supranuclear palsy
Progressive supranuclear palsy (PSP) can cause difficulty with walking and balance (stock image)
Progressive supranuclear palsy (PSP) is a rare, progressive brain disease caused by the toxic tangles of tau proteins in the brain, similar to Alzheimer’s disease.
These tangles damage nerve cells responsible for eye movements, walking, balance and swallowing. It also causes dementia in about 70 percent of cases.
Damage primarily occurs in the brainstem and basal ganglia, which regulate voluntary motor control and habit learning.
Patients may experience a loss of balance while walking, stiffness, awkward movements, slow or slurred speech, trouble swallowing, sensitivity to bright light, trouble sleeping, impulsive behavior, a surprised or frightened facial expression and dizziness.
Also called Steele-Richardson-Olszewski syndrome, PSP is often misdiagnosed as Parkinson’s disease due to the loss of movement control.
The only proven risk factor for PSP is age, with the condition coming on between ages 60 and 70. In rare cases, it can be passed down in families.
About 30,000 Americans have PSP, according to Cure PSP.
There are no treatments for the condition, so doctors focus on managing symptoms.
