How prion disease progresses: more detail

What durations should be quoted?

By form, from the sources on this page. Sporadic CJD runs about 4 to 5 months. Variant CJD averages 13 to 14 months. The inherited CJD phenotypes are usually slower, around 2 years. Fatal familial insomnia is described in review literature as typically longer than a year. Gerstmann-Straussler-Scheinker syndrome has a mean duration of about 5 years, varying by variant.

Within each form, duration varies substantially between individuals, and the codon 129 genotype is one of the modifiers; in fatal familial insomnia, homozygotes have a shorter mean duration than heterozygotes. Published guidance advises communicating both the typical course and the individual uncertainty rather than a single number. There is also a geographical observation in the literature that duration is longer in Japan than elsewhere, which is relevant when reading survival figures from different countries.

How does the illness stage?

Onset is heterogeneous and frequently mistaken for something commoner. The NHS description for sporadic CJD lists early gait difficulty, dysarthria, paraesthesiae, dizziness, diplopia and hallucinations, worsening over a few months. Variant CJD characteristically opens with a psychiatric prodrome, with depression, withdrawal, anxiety, irritability and insomnia, and neurological features following around four months later. In iatrogenic cases the pattern depends on the route of exposure.

The established phase brings ataxia, myoclonus and spasms, progressive cognitive impairment with confusion and poor concentration, neuropsychiatric features including agitation, aggression, paranoia and emotional lability, cortical visual impairment, dysphagia, loss of speech, weight loss and incontinence.

The advanced phase is akinetic mutism, which the 2026 recommendations name as the marker of the advanced stage while noting that survival within it varies. Patients are bedbound, often unaware of surroundings and need continuous care. Death usually follows intercurrent infection, commonly pneumonia, or respiratory failure.

What does current guidance recommend at each stage?

The 2026 multidisciplinary recommendations, published in Age and Ageing with authors from the UK, US, Germany and Japan, are the most specific source available.

Myoclonus: levetiracetam first line in ambulatory patients. Clonazepam reserved for more advanced stages, once walking has been lost, because of benzodiazepine effects on cognition and falls. At end of life, midazolam or levetiracetam by continuous subcutaneous infusion.

Agitation and behaviour: challenging behaviour framed as communication of an unmet need, with non-pharmacological approaches first. The panel suggests a watch-and-wait approach to symptoms such as delusional ideas, which can emerge and resolve quickly, reserving medication for severe distress or risk.

Pain: treat the reversible causes, particularly constipation and pressure injury, with regular paracetamol as first line in a stepped approach, opioids used cautiously, and neuropathic agents for dysaesthesia.

Sleep: environmental and non-drug strategies first, then melatonin, trazodone or low-dose benzodiazepines if those fail, weighed against falls and daytime sedation.

Swallowing and nutrition: oral intake valued while it is safe, with decisions on clinically assisted nutrition and hydration made case by case through a best-interests process with regular reassessment, and speech and language therapy input where oral feeding continues. The panel’s reference list includes evidence that enteral feeding is associated with longer survival in the advanced stages, which is a reason the discussion needs to be explicit about goals rather than defaulted either way.

Symptoms: more detail covers the individual symptoms at greater length.

Why does planning have to start at diagnosis?

Because capacity is frequently lost during the diagnostic process itself. The recommendations advise beginning future care planning as soon as possible, ideally at diagnosis, and note that where no family is available an advocate such as an Independent Mental Capacity Advocate may be appointed. In the UK the SR1 form can accelerate access to benefits.

Palliative care involvement should be early rather than terminal. The recommendations note that in the US palliative care is often underused and referred late. Early involvement is what makes symptom control, preferred place of care and carer support achievable rather than reactive. Palliative and hospice care sets out what those services provide.

What do carers need, and what should be said about risk?

The panel describes family carers as facing high physical, mental and financial strain, and recommends disease-specific information, skills training, practical and personal care support, respite and financial help, alongside peer networks such as the CJD Support Network. In a disease measured in months, respite that arrives after three months of waiting has not been provided.

On transmission, the recommendations state there is no evidence that CJD is transmitted from person to person through regular social and clinical contact, and that routine care requires no infection control beyond standard practice. Additional precautions apply to higher-risk procedures involving brain, spinal cord or posterior eye tissue. People with prion disease, or at increased risk through family or medical history, are not eligible as blood or organ donors and should tell their healthcare team before any procedure. Consented post-mortem tissue donation for prion research is a separate option, and one that some families want to be offered rather than to have to raise.

Where next?

How prion disease progresses is the plain version for families. What to expect covers the practical arrangements, and rapidly progressive dementia and CJD: more detail the diagnostic phase that precedes all of this.

This page summarises published guidance and literature and is not clinical advice. Management of an individual patient, including every medication choice named here, belongs with the treating team.