When Insomnia Becomes Deadly

[ intro ] We’ve all been there — tossing and turning all night for absolutely
no reason. But for the vast majority of people, insomnia
can’t actually kill you. In one very rare, very specific case, however, not only is insomnia deadly — it’s lurking in your genes from the time
you’re born. Familial fatal insomnia, or FFI, is an incredibly rare condition where patients
experience lack of sleep and other psychiatric symptoms, and eventually
die. And though we know what causes it, there’s a lot about that cause we don’t
fully understand. Familial fatal insomnia usually affects adults
as early as their 30s, though there have been a very small number
of cases in teenagers. And yes — it is fatal. Unfortunately, there’s no cure, and patients usually die within a year or
two of showing symptoms. It usually starts when people report having
a hard time falling or staying asleep. When they do sleep, they have a harder time
achieving deep, restful sleep. And their brain activity actually changes. The typical sleep cycles most people experience
are altered for these patients. Sometimes their perceptions while awake during
the day can become dream-like, either hallucinating, seeing double, or reacting to things in the dream. As the disease progresses, patients develop
problems with balancing and walking, and experience actual dreams throughout the
day. But FFI is so rare that these symptoms can
be really misleading. If a patient comes in complaining of hallucinations,
for example, doctors might be more likely to think of something
like schizophrenia. Because FFI is incredibly rare. Only a few dozen cases have been described
in the medical literature, though it might be slightly more common than
that. So where does this disease come from? Well, autopsies of patients with this disease
show something in common — deterioration of tissue in the thalamus. This region is often called a relay center,
connecting different parts of the brain to each other. But it plays a specific role in regulating
your sleep cycles. It’s involved in monitoring sensory information
like vision, and seems to serve as a gate that chooses
when to let that information pass to other parts of your brain. Meaning it may help you become less aware
of your surroundings as you drift off. So why do some people get this thalamus deterioration? That brings us to the “familial” part of the
name — it’s genetic, and we know just which gene
is to blame. FFI is a prion disease — specifically, an inherited one. These are a handful of rare diseases that
cause neural degeneration, all associated with a specific protein called
the prion protein. That protein is coded for by a gene called
PRNP. Variants of this gene can make the protein
mutate, which causes all kinds of problems for your
brain tissue. Quite a few variants in this gene have been
documented, but only one results in the specific deterioration
in the thalamus associated with FFI. And in patients with FFI, you can find this mutated protein in the deteriorated
parts of the thalamus. Another prion disorder, Creutzfeldt-Jakob
disease, also follows a similar pattern — but targets different brain regions that affect
memory, coordination, and vision. We’re not exactly sure how this misshapen
protein causes neural degradation, but some researchers think it involves the
body’s natural process of programmed cell death. Damaged brain regions like the thalamus look
like they died from apoptosis — but the protein can be detected outside of
where the damage is. Which gets to the big mystery about this disease: we don’t really know why we have this protein
in the first place. We really only tend to notice it when it goes
wrong — deteriorating neural tissue and ultimately
leading to death. If it’s not doing anything terribly important
when everything’s ok, but does horrible things when it mutates,
you’d think evolution would get rid of it. But it’s found in other mammals and birds
as well as humans, suggesting there could be a good reason to
keep it around. We just don’t know what that is. Some studies in mice have found that when
they have less of the regular, unmutated prion protein, they have less long-term
potentiation in the hippocampus — though those results haven’t been consistent. Long-term potentiation is the idea that when
a neuron fires repeatedly, it forges stronger synaptic connections, which is theorized to be an important part
of how memory works. Furthermore, when mice have more of this protein
than usual, they have even more synaptic transmission. So, possibly stronger memories. Messing with the amounts of a protein to see
what changes is scientists’ favorite method for figuring
out what that protein does normally. These experiments tell us the prion protein
could be critical for keeping your memory functioning, but not all studies actually agree. Another idea is that the common prion protein is just doing the opposite of what the misshapen
one does — instead of killing our neural tissue, it’s
protecting it. In those same kinds of more-or-less-protein
experiments, mice bred to not have the prion protein would
suffer larger lesions when researchers induced a stroke compared
to normal mice. And having more of that protein seemed to
protect against neural damage. So it’s possible that having a better understanding
of this protei n might unlock some ideas about why brains
deteriorate as they age. While research is ongoing about what makes
this protein work, it could help us understand how memory works and how to prevent some of the neural changes
associated with aging. Which could help us treat more common diseases
like Alzheimer’s and MS, but also help those few people who develop
fatal insomnia. Thanks for watching this episode of SciShow
Psych, which was brought to you with the help of
our community of amazing patrons. We couldn’t make SciShow without your help,
so thanks! If you want to get involved, check out patreon.com/scishow. [ outro ]

19 thoughts on “When Insomnia Becomes Deadly

  1. But: do these patients actually die from the insomnia itself, or do they die from the brain damage that also causes insomnia? There's a big difference.

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