Objective:
Alzheimer's disease (AD) is a neurodegenerative dementia subtype characterized by widespread and continuing cognitive deficits encompassing abilities in memory, language and executive function that exceed the decline observed in normal aging. Such decline has significant consequences for the social functioning of the individual. The objective of this study was to identify the cognitive markers that best differentiate AD from healthy controls and to determine whether affective deficits make an important additional combination to definition of AD.
Method:
Nineteen patients with probable AD and 38 matched healthy control subjects were tested as part of the Brain Resource International Database. Testing included a detailed medical history, a battery ofcognitive tests, for which sound psychometric properties have been established, and psychophysiological recording using EEG and event-related potential (ERP) measures in response to cognitive- and emotion-related tasks.
Results:
Between-subjects ANOVAs showed that the AD group showed marked and pervasive deficits relative to controls, on tests spanning verbal and visual memory, working memory capacity, attention function and vigilance. In addition, the relationship between cognitive decline and general mood (depression) was also examined. Significantly, measures of working and verbal memory abilities showed an inverse relationship with markers of depression and general mood at the time of testing, whereas the opposite or no relationship between such measures was observed in the control group. These findings will be discussed in relation to the psychophysiological measures of brain function during emotion perception and working memory tasks.
Conclusions:
These preliminary findings provide support for the added benefit of the concurrent examination of affective markers with markers of cognitive decline, for the potential determination of an AD diagnosis. Indeed, premorbid depression has been found to act as a risk factor for the development of AD (Ownby et al. Archives of General Psychiatry 2006, 63 530-538). The significance of an integrative neuroscience approach to the assessment of AD and other forms of dementia is supported by these findings.