Could It Be VCP Disease? Understanding the Overlap with Dementia, Parkinson's, ALS, and Movement Disorders

VCP disease — also known as multisystem proteinopathy — is a rare, inherited genetic condition caused by mutations in the VCP gene. It's often misdiagnosed, because the symptoms it causes overlap heavily with several more commonly known conditions. If you or a loved one has been evaluated for one of the conditions below, it's worth knowing how VCP disease fits into the picture.

VCP Disease and Frontotemporal Dementia (FTD)

Frontotemporal dementia is one of the most common misdiagnoses in VCP disease. In fact, VCP disease was first clinically described as "IBMPFD" — inclusion body myopathy with Paget's disease of bone and frontotemporal dementia — because the cognitive and behavioral changes of FTD are a core feature for many patients. What distinguishes VCP disease is that the dementia typically appears alongside progressive muscle weakness and, in many patients, bone disease. Memory clinics that only screen for cognitive symptoms can miss the muscular and skeletal clues entirely.

VCP Disease and Alzheimer's Disease

Because both conditions can involve memory and cognitive decline, VCP disease is sometimes initially explored as Alzheimer's, especially in older patients. The key difference: Alzheimer's does not typically cause the progressive limb-girdle muscle weakness, difficulty climbing stairs, or bone pain that VCP patients experience. When cognitive decline is paired with unexplained muscle weakness, VCP disease should be on the differential.

VCP Disease and Parkinson's Disease

Parkinsonism — tremor, rigidity, slowed movement — appears in a subset of VCP disease patients, which can lead to an initial Parkinson's diagnosis. Unlike typical Parkinson's, VCP-related Parkinsonism often responds poorly to standard Parkinson's medications and is accompanied by muscle weakness patterns that aren't typical of Parkinson's disease alone.

VCP Disease and Dyskinesias / Movement Disorders

Involuntary movements and other movement disorder symptoms can show up in VCP disease, particularly as the disease progresses or in combination with other neurological involvement. When a movement disorder doesn't fit neatly into a standard diagnosis, especially alongside muscle weakness, genetic testing for VCP mutations is worth discussing with a neurologist.

VCP Disease and ALS (Amyotrophic Lateral Sclerosis)

VCP mutations are a recognized genetic cause within the ALS-FTD spectrum. Some VCP disease patients are initially diagnosed with ALS due to progressive muscle weakness and motor neuron involvement. Research consortiums, including the CReATe Consortium, study VCP disease specifically within this ALS-FTD spectrum. Patients with a family history of ALS, FTD, myopathy, or Paget's disease of bone in combination are especially encouraged to ask about VCP genetic testing.

What Makes VCP Disease Different

VCP disease is a multisystem condition — it doesn't stay in one lane. The combination that should raise suspicion for VCP disease, rather than one of the conditions above in isolation, includes:

• Progressive muscle weakness (especially proximal/limb-girdle pattern)

• Cognitive or behavioral changes consistent with FTD

• Parkinsonism that responds poorly to typical treatment

• Paget's disease of bone

• A family history that includes ALS, FTD, myopathy, or bone disease across generations

Get Evaluated

If any of this sounds familiar, genetic testing for VCP mutations can provide clarity. Cure VCP Disease maintains a global patient registry and can connect you with clinicians and researchers who understand this disease.