Cognition will be evaluated using a standard neuropsychological assessment (investigating executive function, memory, attention, language and visuo-constructive abilities) and a 7 days experience sampling method which evaluates cognition in daily life. Brain anatomo-functional study will include a brain MRI and two Tc-99m-HMPAO SPECT performed respectively with and without intravenous injection of acetazolamide in order to measure cerebral blood-flow and cerebrovascular reserve capacity.