Reviewed by the Help Dementia Editorial Team — our editors review every article for accuracy against guidance from the National Institute on Aging, the Alzheimer’s Association, and peer-reviewed sources.
When someone mentions dementia, most people think of Alzheimer’s disease. It accounts for 60-70% of all dementia cases, making it the dominant narrative in popular understanding of cognitive decline. But here’s what often gets overlooked: nearly 40% of all dementia cases are caused by something else entirely. Four types of dementia—frontotemporal dementia, Lewy body dementia, vascular dementia, and the rarer progressive supranuclear palsy and corticobasal degeneration—collectively account for between 20-39% of all dementia diagnoses, yet they remain largely unknown outside medical circles.
Together with mixed dementia, which affects 23% of all diagnoses, these lesser-known types represent a significant portion of people struggling with cognitive decline and their families searching for answers. Why does this matter? Because each type of dementia progresses differently, responds to different treatments, and requires entirely different care approaches. A person showing the early signs of Lewy body dementia might be misdiagnosed with Alzheimer’s, meaning they’ll miss out on the specific interventions that could help them. Similarly, someone with vascular dementia might receive treatment for Alzheimer’s that won’t address their underlying condition. This article explores four dementia types that deserve far more attention than they receive, explains how they differ from Alzheimer’s, and examines why getting an accurate diagnosis matters so much.
Table of Contents
- What Are Frontotemporal Dementia and Why Do Personality Changes Come First?
- Lewy Body Dementia: When Hallucinations and Movement Problems Accompany Cognitive Decline
- Vascular Dementia: When Blood Flow Problems Damage the Brain
- Rarer Dementia Types and Why They Demand Recognition
- Why Correct Diagnosis Changes Everything About Treatment and Care
- The Genetic Component: Family History as a Warning Sign
- Getting Accurate Diagnosis and Finding Specialized Care
- Conclusion
What Are Frontotemporal Dementia and Why Do Personality Changes Come First?
Frontotemporal dementia is a type of cognitive decline that defies the Alzheimer’s pattern most people expect. While Alzheimer’s typically starts with memory loss, FTD hits the brain’s frontal and temporal lobes—the regions responsible for personality, judgment, and language. The result: behavioral and personality changes occur before memory loss takes hold. A person with FTD might become socially inappropriate in ways that seem completely out of character, make impulsive decisions they would never have made before, or lose the ability to empathize with people they love. Memory itself often remains relatively intact in the early stages, which can make FTD especially confusing for families who don’t understand why their loved one is acting like a different person while still remembering details from their life. FTD accounts for 1-8% of all dementia cases, with a prevalence of 15-22 people per 100,000.
The disease progresses relatively quickly, often appearing in people younger than typical Alzheimer’s patients. This matters because a 52-year-old showing sudden personality changes and poor judgment might be told they have depression or a mental health crisis, when in fact their brain is physically degenerating. Almost 40% of FTD cases are familial—meaning they run in families—linked to mutations in genes like MAPT, GRN, and C9orf72. If someone in your family has been diagnosed with FTD, you’re far more likely to develop it than if you had a family member with Alzheimer’s. The disease presents in three clinical subtypes: behavioral variant FTD (bvFTD), where personality changes dominate; semantic dementia, where language meaning gradually disappears; and progressive nonfluent aphasia, where speech becomes halting and difficult. Knowing which subtype someone has becomes crucial for predicting how the disease will progress and what kind of support they’ll need.
Lewy Body Dementia: When Hallucinations and Movement Problems Accompany Cognitive Decline
Lewy body dementia is the third most common dementia type after Alzheimer’s and vascular dementia, yet it remains deeply underrecognized. The disease is caused by abnormal deposits of a protein called alpha-synuclein—known as Lewy bodies—accumulating in the brain. These deposits attack multiple brain regions, which is why Lewy body dementia creates such a distinctive and confusing symptom profile that often leads to misdiagnosis. Incidence rates show that dementia with Lewy bodies (DLB) occurs in about 7.10 per 100,000 person-years, and when you include Parkinson’s disease dementia (PDD), which is essentially the same underlying pathology, LBD accounts for 3-11% of all dementia cases. The hallmark characteristics of Lewy body dementia are hallucinations, fluctuating alertness that can change hour to hour, sleep problems (including REM sleep behavior disorder, where people act out their dreams), and Parkinson-like movement symptoms including tremor, rigidity, and slow movement.
Here’s where it gets tricky: if someone with LBD sees vivid hallucinations—perhaps people or animals that aren’t there—they might be given antipsychotic medications that help with Alzheimer’s psychosis. But antipsychotics can be dangerous for people with Lewy body dementia, sometimes causing severe reactions. A person might fluctuate between appearing alert and engaged one moment and confused or drowsy the next, which can be misinterpreted as depression or medication side effects rather than the disease itself. The combination of visual hallucinations, movement difficulties, and cognitive changes creates a perfect storm for misdiagnosis. Many people with Lewy body dementia initially receive a Parkinson’s diagnosis because the movement problems appear first, then get reclassified later when dementia becomes apparent. Others are labeled with Alzheimer’s until their family reports the hallucinations and sleep acting-out behaviors that should have pointed toward Lewy bodies from the start.
Vascular Dementia: When Blood Flow Problems Damage the Brain
Vascular dementia is the second most common type of dementia after Alzheimer’s, accounting for 15-20% of all cases. Unlike Alzheimer’s, which is rooted in protein accumulation, vascular dementia occurs when the brain’s blood supply is disrupted—through strokes, mini-strokes, or chronic reduction in blood flow from narrowed vessels. This distinction matters enormously because it means vascular dementia is potentially preventable or slowed through aggressive management of cardiovascular risk factors like blood pressure, cholesterol, diabetes, and smoking. The progression of vascular dementia often differs notably from Alzheimer’s. Rather than a steady, gradual decline, vascular dementia frequently progresses in a step-wise pattern—the person remains relatively stable, then a stroke occurs and suddenly their cognitive abilities drop noticeably, then they plateau again until the next vascular event.
This pattern can actually make diagnosis easier if doctors are looking for it, but it’s often missed because people focus on the overall decline rather than the pattern underneath. Someone might be doing reasonably well cognitively but have poor executive function—difficulty planning, organizing, and problem-solving—because of damage to specific brain regions affected by vascular events. The relationship between vascular events and Alzheimer’s further complicates the picture. Many people diagnosed with Alzheimer’s disease actually have underlying vascular pathology contributing to their symptoms. In fact, 23% of all dementia diagnoses involve mixed-type dementia—a combination of multiple pathologies. Someone might have both Alzheimer’s plaques and tangles plus evidence of prior strokes, meaning they need treatment approaches that address both conditions.
Rarer Dementia Types and Why They Demand Recognition
Beyond the more common types lies a group of rare dementias that, while individually uncommon, collectively affect thousands of people and their families. Progressive supranuclear palsy (PSP) is particularly important to understand because it’s the second most common tauopathy—a disease caused by tau protein buildup—after Alzheimer’s disease itself. PSP is characterized by vision difficulties, loss of balance, and a distinctive pattern of backward falls that can be so severe patients sometimes fracture their skulls. The disease progresses rapidly, and people often report that the cognitive decline matters less to them than the movement and vision problems that increasingly isolate them. Corticobasal syndrome (corticobasal degeneration) represents another rare but devastating dementia type.
It causes both cognitive decline and movement difficulties, but with a striking asymmetry—symptoms appear worse on one side of the body than the other. Some patients report an especially disturbing symptom called “alien limb phenomenon,” where one arm seems to act independently of their will. These rarer types might account for only 1-2% of all dementia cases individually, but they represent real people whose symptoms often baffle their doctors because they’re unfamiliar with the diagnosis. Why these rarer types matter is that genetic research has revealed shared mechanisms between FTD, PSP, and corticobasal degeneration, suggesting they may be different manifestations of overlapping pathologies. Genetic mutations that increase risk for one sometimes increase risk for others. This research is building toward better understanding of what goes wrong when tau and other proteins misfold in the brain, which could eventually lead to treatments for all these conditions.
Why Correct Diagnosis Changes Everything About Treatment and Care
The fundamental reason all these lesser-known dementia types matter is that they respond differently to treatments. Someone with Lewy body dementia taking certain antipsychotics might suffer serious adverse effects that wouldn’t occur in someone with Alzheimer’s. A person with vascular dementia benefits enormously from aggressive management of their cardiovascular health in ways someone with Alzheimer’s might not. Someone with FTD might need completely different behavioral management strategies than someone with Alzheimer’s experiencing similar-looking behavioral symptoms. Getting the diagnosis right isn’t about satisfying medical curiosity—it’s about accessing treatments and strategies that actually work. Early and accurate diagnosis is critical because different dementias progress at different rates and respond to different interventions. Some drugs that slow Alzheimer’s progression don’t help with other dementia types.
Cognitive rehabilitation approaches that work for one type might not help another. Even non-pharmacological interventions—things like exercise programs, cognitive stimulation, or social engagement—sometimes need to be tailored to the specific type of dementia someone has. A person with vascular dementia and uncontrolled blood pressure needs different medical management than someone with Alzheimer’s and well-controlled cardiovascular health. The challenge is that many primary care doctors haven’t been trained extensively in recognizing these less common types. Someone with Lewy body dementia might visit their doctor three times before the hallucinations, movement symptoms, and cognitive changes are properly connected to a Lewy body diagnosis. Someone with FTD might be referred to psychiatry for behavioral issues when they need a neurologist investigating brain degeneration. Getting to a specialist who recognizes these rarer types can take years, during which time a person’s condition progresses without the right kind of support.
The Genetic Component: Family History as a Warning Sign
Nearly 40% of frontotemporal dementia cases are familial, running through families and linked to specific gene mutations. This makes FTD distinctive—while Alzheimer’s can be genetic, the familial form is less common. If you have a parent or sibling with FTD, particularly if they developed symptoms before age 65, your risk of developing FTD is substantially elevated. The genes implicated—MAPT, GRN, and C9orf72—are now testable, meaning genetic counseling and testing can clarify risks for family members. For other dementia types, the genetic picture is murkier but still important.
Some cases of Lewy body dementia have genetic components, though most are sporadic. Vascular dementia typically isn’t inherited directly, but cardiovascular risk factors often run in families—high blood pressure, diabetes, and arterial disease tend to cluster in families. If your parent had a stroke at 55, your own cardiovascular health becomes especially important. The practical implication: if dementia runs in your family, particularly if it appeared early or in an unusual pattern, getting a clear diagnosis in your relative becomes even more important. A genetic diagnosis can open doors to clinical trials, predictive testing for family members, and potentially preventive interventions. Some families discover through genetic testing that what they thought was Alzheimer’s in a parent was actually FTD, which entirely changes how they understand their own future health risks.
Getting Accurate Diagnosis and Finding Specialized Care
Navigating toward an accurate diagnosis for lesser-known dementia types requires persistence. Many people see their primary care doctor first, who might order basic cognitive testing and an MRI, then refer to neurology if something seems unusual. However, not all neurologists have extensive experience diagnosing rarer dementias. Memory clinics, often affiliated with Alzheimer’s disease research centers, increasingly include specialists trained in differentiating between dementia types using specialized imaging, cerebrospinal fluid biomarkers, or PET scans that can show distinctive patterns for different diseases.
Finding the right specialist sometimes means reaching out to dementia research organizations, university medical centers, or calling major hospitals to ask who specializes in non-Alzheimer’s dementias. Some specialized centers have developed expertise in specific rare types through research programs. If you suspect your loved one might have something other than Alzheimer’s—particularly if you’re seeing unusual behavioral changes, movement problems, hallucinations, or a step-wise progression pattern—mentioning these specifics to your doctor is important. These details are the clues that point toward correct diagnosis.
Conclusion
Alzheimer’s disease dominates the dementia conversation, but it doesn’t dominate the disease itself. Frontotemporal dementia, Lewy body dementia, vascular dementia, and rarer conditions like progressive supranuclear palsy and corticobasal degeneration collectively account for a substantial portion of dementia cases. These aren’t rare curiosities that only specialists need to know about—they affect hundreds of thousands of people and their families who deserve accurate diagnosis and appropriate treatment.
The gap between what these people have and what they’re told they have can mean years of receiving the wrong interventions while their condition progresses unaddressed. If something about a dementia diagnosis doesn’t feel right—if symptoms don’t match what you’ve read about Alzheimer’s, if progression seems different than expected, if hallucinations or movement problems appear—that intuition is worth pursuing. Seeking a second opinion from a specialist experienced in multiple dementia types isn’t overreach; it’s advocating for the accurate diagnosis that changes everything about how someone receives care. Understanding that dementia isn’t one disease but many is the first step toward getting it right.
