This Seminar is based on discussions that took place during an Expert Conference sponsored by the International Psychogeriatric Association. Presenters were asked to review published work relevant to their assigned topics and to summarise the available evidence, areas of agreement, areas of uncertainty, and research priorities. This was not a consensus conference, but rather an opportunity to review available data and offer an expert opinion on where mild cognitive impairment stands as a
SeminarMild cognitive impairment
Section snippets
Background and conceptual development
Many attempts have been made to define the clinical entity of declining cognitive abilities associated with ageing. In the early part of the 19th century, Prichard1 identified the earliest stage of dementia as impairment of recent memories with intact remote memories. More than a century later, Kral2 espoused a contrasting viewpoint, with his description of benign senescent forgetfulness, in which fairly unimportant data and parts of an experience are not recalled and in which the forgotten
Pathophysiology
Much clinical evidence exists for the detrimental effects of anticholinergic drugs on cognition.19 A central cholinergic deficit is thought to be present in amnestic mild cognitive impairment, related to loss of neurons in the nucleus basalis of Meynert,20 although findings of a post-mortem study showed upregulation of choline acetyltransferase activity in the frontal cortex and hippocampus.21 This upregulation could be a compensatory mechanism, which is suggested by recruitment of memory and
Diagnosis
In terms of research diagnostic criteria, there is uncertainty about whether a lumping-together approach to mild cognitive impairment33 is preferable to a splitting approach, with various categories of the disorder.34 Prospective cohort studies are underway to establish whether amnestic and non-amnestic subtypes of mild cognitive impairment (figure)35 have different prognoses for progression to dementia and which type of dementia they predict35 and their effect on survival times.36 It is
Management
The first wave of clinical trials aimed at symptomatic drug treatment for amnestic mild cognitive impairment over 6 months to 3 years have been largely unsuccessful.76 Results from the Memory Impairment Study16 showed no significant differences in the probability of progression from amnestic mild cognitive impairment to Alzheimer's disease in patients allocated vitamin E or donepezil, compared with placebo, during the 3 years of treatment, although significant differences were recorded
Prevention
Although no specific disease-modifying treatment has yet been shown to be effective for any of the degenerative dementias, control of risk factors might prove useful. The best evidence available so far is in the control of isolated systolic hypertension.23 The idea of interventional epidemiology proposed by Ritchie13 for mild cognitive impairment will probably lead to international randomised controlled trials linking the consortia of investigators interested in the causes and treatment of mild
Conclusions
The syndrome of mild cognitive impairment as a transition state between normal ageing and dementia has increased awareness that memory complaints in elderly people, particularly when accompanied by subtle cognitive performance difficulties, should be assessed in a systematic way by clinicians. Prospective cohort studies with clinicopathological correlations will help to clarify whether some of the subtypes of mild cognitive impairment are prodromal stages of specific dementias, paving the way
Search strategy and selection criteria
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Participants of the International Psychogeriatric Association Expert Conference on mild cognitive impairment are listed at the end of this Seminar