Prion diseases share a handful of common symptoms, including fatigue and lethargy, cognitive decline (including confusion, short-term memory loss and dementia), hallucinations, rigidity (muscle stiffness), and changes in ability to walk and talk. But just as not all prion diseases are contracted in the same way, not all prion diseases have the same symptoms.
Insomnia is the early red flag, the hallmark of FFI, but sleep cycle disturbances aren't the only problem those afflicted with the disease experience. It moves through four distinct stages as it progresses. The first symptoms of FFI usually strike when a person is middle-aged, about 48 years old (although its onset has been seen as early as age 19 and as late as age 72), and the disease progresses rapidly. While some who develop FFI may live for two to three years, others may die within a year.
The first stage of the disease begins with insomnia, which typically gets worse over about a span of about four months. Some patients, however, only recognize it as a symptom something is wrong long after other problems of the disease begin to make themselves known. During these initial months FFI sufferers also begin to experience psychiatric complications, including panic attacks, paranoia and phobias (including, perhaps not surprisingly, insomnia phobia, which is the fear of not being able to sleep). During stage one, patients also report vivid dreaming when they are able to sleep.
During stage two, which for some lasts about five months, psychiatric symptoms persist and worsen; sufferers begin to hallucinate and become agitated, and the sympathetic nervous system begins to kick into overdrive. This is called sympathetic hyperactivity, and it causes a series of symptoms that include an increase in cortisol levels (that's the body's stress hormone), heart rate (tachycardia), blood pressure (hypertension), body core temperature (hyperthermia) and perspiration (hyperhydrosis) and breathing (tachypnea). It's in this stage when FFI begins to cause psychomotor problems such as short-term memory loss, personality and mood changes (including depression and anxiety), and motor disorders including movement and gait changes.
It's during third stage of FFI, which is a short stage of about 90 days, when the wake-sleep cycle becomes completely disrupted and total insomnia begins.
Stage four -- the end-stage of FFI -- is defined by rapid cognitive decline and dementia. This stage may last as long as six months. In the end, FFI causes the inability to voluntarily move or speak (called akinetic mutism), followed by coma, and ultimately death.