Background: Cognitive reserve theory emphasizes that people process information in different ways depending on the tasks performed. Different environmental stimuli may provide varying degrees of protection against neurodegenerative diseases in the elderly. Objective: To analyze the association between self-direction of main lifetime occupation and cognitive performance in elderly population. Material and methods: 112 senescent that reside in Buenos Aires' city were assessed. A descriptive-correlational design of cross section was used. Results: The statistical processing applied indicates positive correlations between the level of overall complexity, lifetime occupation and cognitive performance: Analogies (r = .43 ,p b .05), Vocabulary (r = .54, p b .05), and Fonological fluency (r = .23, p b .01), Cubes (r = .34, p b .01), TMTB (r = .38, p b .01), Global IQ (r = .50, p b .01), Verbal IQ (r = .52, p b .01) and Executive IQ (r = .34, p b .01). Positive associations were observed between the degree of noveltyroutine of main lifetime job and cognitive performance: Analogies (r = .26 ,p b .05), Vocabulary (r = .39, p b .05), Cubes (r = .21, p b .05), TMTB (r = .31, p b .01), Global IQ (r = .34, p b .01) and Verbal IQ (r = .37, p b .01).Conclusion: It can be concluded that more complex and less routine activities could be associated with better performance in some cognitive areas that constitute the subject's cognitive reserve.Background: Rapidly progressive dementia (RPD) was considered rare and most of the studies have focused on prion diseases. However, advances in immune-mediated disorders have allowed the diagnosis of previously unrecognized treatable dementias. Objective: To describe the prevalence and causes of RPD in a neurology unit of a tertiary hospital and which are potentially reversible. Patients and methods: This study is a cross-sectional evaluation of all inpatients in a neurologic unit of a tertiary hospital in Brazil