Presence of Anti-RACH Antibodies and Neurocognitive Disorder in Myasthenic or Alzheimers's Patients.

"Each patient will undergo a blood draw for the analysis of RACH antibodies in serum.~Also an aliquot of frozen spinal fluid of patient kept in biobank ( spinal fluid taken during a puncture as part of routine care) will be used for the analysis of RACH antibodies."

"Each patient will undergo a blood draw for the analysis of RACH antibodies in serum.~Also an aliquot of frozen spinal fluid of patient kept in biobank ( spinal fluid taken during a puncture as part of routine care) will be used for the analysis of RACH antibodies."

Frozen spinal fluid of 10 healthy controlled stored in a biobank in Munster, Germanywill be compared to the ones of Adults with Myasthenia and Adults with Alzheimer's disease