Clinical Symptoms of CJD

Symptoms of prion disease can vary widely and often mimic other illnesses.

Sporadic CJD presents itself in a variety of ways, though typically looks homogeneous towards the end of the disease duration^1,2. Clinical presentation can include a "classic CJD" phenotype, demonstrating cognitive impairment and cerebellar impairment such as gait ataxia or incoordination (MM1 & MV1). However, most cases of CJD do not present with a clinical syndrome that is immediately identifiable as sCJD. Many cases will present with cognitive impairment and may initially be misdiagnosed as a different type of dementia (e.g., Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies)(MV2).

Other cases may present with isolated visual symptoms (i.e., Heidenhain variant, MM1) or pure gait ataxia for a period of time before other symptoms emerge (i.e., Oppenheimer-Brownell variant, VV2). Nevertheless, some cases may present with a non-specific psychiatric syndrome, as a mood disorder or anxiety. It is not unusual for sCJD to be misdiagnosed as other illness because of symptoms that overlap with more common conditions^3,4. Oftentimes the illness has to progress and include more common symptoms, such as myoclonus, for clinicians to appropriately arrive at a clinical suspicion of the disease.

The average duration of sCJD is 4-6 months, from illness onset until the patient passes. The majority of patients with sCJD succumb to their illness within a year, but some cases can survive a year or two. However, because of the difficulty in diagnosing sCJD, it is not uncommon for there to be a very short time period between diagnosis and death (e.g., one month). sCJD is typically a disease of mid-to-late life, with an average age of onset in the mid-60's, but with cases as young as 14 and as old as 101.

Variably Protease-Sensitive Prionopathy (VPSPr) is a rare sporadic form of prion disease characterized by speech difficulties and psychiatric signs, followed by cognitive impairment and progressive motor impairment⁶. Many of these cases have a longer duration than sCJD and are initially misdiagnosed as a non-Alzheimer's type of dementia (e.g., dementia with Lewy bodies, frontotemporal dementia).