Differential effects of age on prospective and retrospective memory tasks in young, young-old, and old-old adults.

Remembering to do something in the future (termed prospective memory) is distinguished from remembering information from the past (retrospective memory). Because prospective memory requires strong self-initiation, Craik (1986) predicted that age decrements should be larger in prospective than retrospective memory tasks. The aim of the present study was to assess Craik's prediction by examining the onset of age decline in two retrospective and three prospective memory tasks in the samples of young (18-30 years), young-old (61-70 years), and old-old (71-80 years) participants recruited from the local community. Results showed that although the magnitude of age effects varied across the laboratory prospective memory tasks, they were smaller than age effects in a simple three-item free recall task. Moreover, while reliable age decrements in both retrospective memory tasks of recognition and free recall were already present in the young-old group, in laboratory tasks of prospective memory they were mostly present in the old-old group only. In addition, older participants were more likely to report a retrospective than prospective memory failure as their most recent memory lapse, while the opposite pattern was present in young participants. Taken together, these findings highlight the theoretical importance of distinguishing effects of ageing on prospective and retrospective memory, and support and extend the results of a recent meta-analysis by Henry, MacLeod, Phillips, and Crawford (2004).

Dimensional phenotypic analysis and functional categorisation of mutations reveal novel genotype-phenotype associations in Rett syndrome.

We aimed to improve the understanding of genotype-phenotype correlations in Rett syndrome (RS) by adopting a novel approach to categorising phenotypic dimensions - separating typicality of presentation, outcome severity and age of onset - and by classifying MECP2 mutations strictly by predicted functional attributes. MECP2 mutation screening results were available on 190 patients with a clinical diagnosis of RS (140 cases with classic RS, 50 with atypical RS). 135 cases had identified mutations. Of the 140 patients, 116 with classic RS (82.9%) had an identified mutation compared with 19 of 50 patients (38%) with an atypical presentation. Cases with early onset of regression and seizures, and those with clinical features that might indicate alternative aetiologies, were less likely to have mutations. Individuals with late truncating mutations had a less typical presentation than cases with missense and early truncating mutations, presumably reflecting greater residual function of MECP2 protein. Individuals with early truncating mutations had a more severe outcome than cases with missense and late truncating mutations. These findings held when restricting the analysis to cases over 15 years of age and classic cases only. Previous findings of variation in severity among the common mutations were confirmed. The approach to phenotypic and genotypic classification adopted here allowed us to identify genotype-phenotype associations in RS that may aid our understanding of pathogenesis and also contribute to clinical knowledge on the impact of different types of mutations.