Over the last two decades, the importance of executive functions in successful adaptive living has been increasingly recognized. Hence, investigation of executive functioning has become a core component of neuropsychological assessment. At present, correct identification is seen as crucial to ensuring adequate treatment, compensation and support. It is argued here that, in the medico-legal arena especially, but also in clinical practice, neuropsychological assessment may rely too heavily on data derived from office-based tests of executive functioning both for the identification of deficits and also for the prediction of their real world consequences. This paper discusses the discriminant and ecological validity of such tests and implications for the future assessment of executive functioning. Additionally, the importance of reliable behavioural observations, made in more ecologically valid environments than purely the consulting room is stressed.

Both Parkinson's disease (PD) and dementia with Lewy bodies (DLB) share a common neuropathological marker, the presence of Lewy bodies in brain stem and basal forebrain nuclei. DLB, in addition, is associated with Lewy bodies in the neocortex, and, in it's more common form, with Alzheimer-type pathological markers, particularly amyloid plaques. Published neuropsychological studies have focused on the differential profiles of DLB and Alzheimer's disease (AD). However, it is presently unclear whether DLB should be classified as a variant of AD or PD. In the present study we compare a healthy age-matched control group with three groups of patients, one with DLB, and two with PD. One of the PD groups was early in the course (PD-E) and the second, more advanced group (PD-A), was matched on severity of cognitive impairment with the DLB group. The results show that DLB was associated with a different pattern of neuropsychological impairment than the PD-A group, particularly in tests believed to be mediated by prefrontal cortical regions.

The performance of a group of 12 amnesics of mixed aetiology was compared with that of two groups of normal subjects on a priming task in which subjects' spontaneous definitions of homonyms were biased in accordance with the sense of interactive context words which had earlier been shown with the homonyms. The amnesics showed significant and normal levels of interactive context priming even when the amount of attention paid to the interactive context words was minimized during training. Reducing the amount of attention paid to the context words during training did, however, decrease the amount of priming, shown by both groups of subjects, to the same degree. It also decreased recognition of trained homonym-context word pairs to a similar extent in amnesics and normal people. In an additional condition of the study, it was shown that normal subjects were aware of the meaningful relationship between homonyms and context words even when the amount of attention they paid to context words was minimized during training. Priming seemed to be stochastically independent of recognition and was also unrelated to signs of frontal lobe damage, intelligence or explicit memory. All three groups of subjects showed similar and significant levels of priming regardless of whether or not only definitions that made no direct reference to the context words were scored. It was concluded that amnesics have preserved priming for interactive context words that are encoded with low levels of attention even though there is evidence that they have a disproportionate recognition deficit for this kind of information under these conditions. The theoretical implications of the results are discussed.

No abstract