In 3 hypertensive patients, aged 57 to 66, profound behavioral and personality changes occurred rather abruptly, characterized by total loss of spontaneous activity and initiative, apathetic behavior, passivity, lack of drive and motivation, loss of interest for any of previous occupations and hobbies, and total flatness of affect. Neurological examination was normal or only showed mild extra-pyramidal signs. Neuropsychological evaluation was only remarkable for mild intellectual impairment suggestive of frontal lobe dysfunction. None of the 3 patients fulfilled criteria for dementia or severe depression. This neurobehavioral syndrome has been coined "athymhormic syndrome" (Habib & Poncet, 1988), a term emphasizing the specific defect in drive ("horme") and affect ("thumos"). Electrical and clinical heart examination was unremarkable. Blood pressure was always found within normal limits during hospitalization, including 24-hour monitoring in one case. However, all patients were known as hypertensive in the past, with repeated bouts of high blood pressure (up to 270 mmHg systolic in one case). X-ray CT-scan was usually normal or showed non-specific white matter changes (so-called "leukoaraiosis"). In all 3 cases, a brain MRI scan showed multiple small infarcts mainly involving deep subcortical structures (caudate nuclei and/or adjacent periventricular white matter) of both hemispheres, consistent with the definition of lacunes.(ABSTRACT TRUNCATED AT 250 WORDS)