Seven French university hospitals will participate in this multicentric prospective, blinded and randomized study. The investigators designed 3 study groups: Lorazepam 2.5mg, Placebo (microcrystalline celluloses) and no premedication at all. The third group (no premedication) is necessary in order to evaluate a placebo response, which may be significant on anxiety level and patients perceptions of care. It was calculated that 969 patients had to be included in order to obtain a 5 point difference between groups on the EVAN score with 80 % statistical power, leading to the inclusion of 1200 patients with an estimated maximum dropout rate of 15 %. All adults below 70 years and scheduled for elective surgery under general anesthesia can be included after information by an anesthesiologist in charge of the study and written informed consent. Non inclusion criterions are: a weight below 45 Kg, a counter indication to benzodiazepine, surgeries that could impair cognitive functions (cardiac or neurologic surgery), usual use of neuroleptics or lithium, drug addiction or former cognitive disease. The technique of anesthesia will be decided by the attending anesthesiologist, who will be unaware of the premedication technique, independently of the study protocol.

Inclusion Criteria:

• male or female aged 18 to 70 years or more;

• About a weight greater than 45 kg;

• Subject to benefit from a scheduled surgery under general anesthesia;

• Topic respecting the ambivalence clause defined below:

  1. Having no cons-indication to the use of benzodiazepines;
  2. Having no known allergy to benzodiazepines;
  3. May be a candidate for the prescription of premedication;

• Topic able to complete a self-administered questionnaire;

• Subject has signed a written informed consent and agreeing to abide by the instructions of the Protocol

Exclusion Criteria:

• - Topic of over 70 years;
• Topic 45 kg or less;
• Topic demanding to receive anxiolytic premedication;
• Subject severe respiratory insufficiency;
• Topic minor, pregnant or breastfeeding, about not being affiliated to the social security system;
• Topic for which surgery is performed under local anesthesia;
• Subject unable to perform only a self-administered questionnaire (inability to read French, severe cognitive impairment);
• Subject to which the scheduled surgery may cause postoperative cognitive dysfunction (intracranial surgery, extracorporeal circulation);
• Topic scheduled for obstetrical surgery or outpatient;
• Subject treated with antipsychotic (neuroleptic or lithium);
• Subject with cognitive impairment already documented (Alzheimer, dementia, neurological sequelae);
• Subject active consumer of narcotics;
• Subject has not signed informed consent.