Assessment of cognitive impairment and dementia using informant reports

When assessing cognitive impairment and dementia, clinicians often seek information from informants to complement the findings from cognitive tests. In recent years, a number of standardized methods have been developed for collecting informant data, but these are not widely known. There are several advantages of using these methods including: everyday relevance, acceptability, useability with nontestable subjects, administration by telephone or mail, potential longitudinal perspective, and greater cross-cultural portability. This review identified 12 scales measuring cognitive impairment as a continuum, and four instruments for diagnosing dementia on the basis of informant data. Research on the psychometric properties of these instruments is reviewed. It is concluded that informant-based measures tap a global factor of cognitive impairment, are highly reliable, correlate with cognitive tests, and discriminate demented from nondemented subjects. Non-cognitive factors and informant characteristics are also likely to influence informantsʹ ratings, but less is known about these influences. Although informant-based methods are a comparatively recent development, existing findings support their use as a complement to cognitive testing, particularly in assessment of dementia.