"Stiff Person Syndrome" (SPS) is a rare neurological disease with a silly name but serious symptoms.
Not in fact a disorder caused by an overdose of Viagra, the defining feature of SPS is uncontrollable muscle rigidity, which comes and goes in bouts, but generally gets worse over time. However, other symptoms are seen including depression, anxiety, and other neurological features such as cerebellar ataxia.
What causes SPS? Well, it's been known for over 20 years that most SPS patients have antibodies against the enzyme GAD65, which is required for the production of GABA, the main inhibitory neurotransmitter in the brain. The body shouldn't be producing antibodies against its own proteins, but unfortunately this does happen quite often, for various reasons, and the result is autoimmune diseases.
So this all seems to make sense. We know that GABA causes muscle relaxation by reducing the brain's input to the muscles. This is ...
