Lumbar puncture is a diagnostic procedure performed as part of the etiological assessment of cognitive disorders. Despite good tolerance and very rare complications, lumbar puncture is still perceived as being painful or anxiety-provoking by patients. Hypnosis could improve pain and anxiety when performing lumbar puncture.

Lumbar puncture is an invasive procedure potentially inducing pain and anxiety indicated in elderly patients for cognitive assessment. Indeed, the measure of amyloid biomarkers and tau in the cerebrospinal fluid is useful in the etiological diagnosis of cognitive disorders. With the ageing of the population and the increase incidence of cognitive disorders, this diagnostic procedure will be more and more frequent. Many studies have shown the efficiency of hypnosis during invasive procedure, especially in young children. The absence of side-effect is a major asset in elderly patients at high iatrogenic risk. It represents an interesting alternative to anxiolytic or sedative treatments. Nevertheless, its effectiveness in the elderly during lumbar puncture remains to be demonstrated. Investigators hypothesized that hypnosis may decrease pain and anxiety during lumbar puncture associated to setting comfort situation (relational care, music, transcutaneous anesthesia).

Inclusion Criteria:

• Age ≥ 70 years old
• Indication for a lumbar puncture for etiological diagnosis of cognitive impairment
• Understanding French Language
• Written and informed consent for this study signed by the patient
• Affiliated to Health Insurance

Exclusion Criteria:

• MMS< 17 or cognitive impairment not allowing informed consent
• Contraindication to lumbar puncture
• Refusal to sign the written and informed consent
• Patient deprived of freedom by court or administrative order

the investigator will blindly collect the subject's self-rated pain and anxiety scales.