published_or_final_version / Medicine / Master / Master of Medical Sciences

This study investigated the utility of the cognitive measures of the Dean-Woodcock Neuropsychological Assessment System (D-WNAS) in the differential diagnosis of Alzheimer dementia (AD) from depression. Past research has found an overlap of symptoms in the early stages of AD and those found in geriatric depression. In both instances, patients are likely to report memory loss, attention deficits, and mood disturbances. As a result of this similarity, differentially diagnosing one from another is a vexing problem for the clinical practitioner. Although a number of screening measures have been offered, none have proven to be clinically useful. Some have proposed this is the result of reliance upon use of single-factor measures. Indeed, many have proposed a multiple factor assessment model would be of more utility in diagnosing AD and depression. Considering the importance of an accurate diagnosis in treatment, this study utilized a multiple factor cognitive model offered by the Dean-Woodcock Neuropsychological Assessment System to differentiate AD from depression.Specifically, subtest scores of the Woodcock-Johnson III - Tests of Cognitive Ability (WJ-III; cognitive measure of the Dean-Woodcock Neuropsychological Assessment System) were compared. Participants (n = 172) fell into one of three groups (i.e. Depressed, Demented, or Normal) based on the diagnoses of a board certified neurologist and neuropsychologist. Results showed clinical groups performed more poorly than normal participants on tests of the WJ-III. In addition, AD participants differed significantly from depressed participants on the Visual Matching and Spatial Relations tests of the WJ-III. However, in all, the WJ-III demonstrated a classification hit rate of less than 70%. Although groups were found to differ in specific ways, the classification hit rate of the WJ-III suggested it could not differentially diagnose AD from depression alone. / Department of Educational Psychology

The purpose of the current study was to explore the relationship between cognitive status and depression in a sample of geriatric patients. Participants included 282 geriatric patients ranging in age from 65 to 96 years who were classified according to diagnosis as: DAT, VaD, MCI, and Norm. All were referred for neurocognitive testing from the Geriatric Assessment Program (GAP) at the University of North Texas Health Science Center (UNTHSC) in Fort Worth, Texas. This study sought to identify factor structures for two versions of the GDS using a geriatric sample of cognitively impaired and intact patients. It then compared these factors to each other to determine whether the GDS-15 is truly a shorter version of the GDS-30. These were then compared to a previously determined factor structure. This study explored whether the four-factors of the GDS-30 are able to differentiate cognitive diagnostic groups. Further, this study sought to identify whether the severity of cognitive decline impacted GDS factor score for each of the cognitively impaired groups. Results revealed a two-factor model of the GDS - 15 and a four-factor model with the GDS - 30. The GDS-15 factors did not differ from the first two factors of the GDS-30. Comparison between the GDS-30 factor structure and that reported by Hall and Davis (in press) revealed no significant differences despite the inclusion of a normal, non-demented group in the current study. Comparisons of subscale scores revealed that DAT patients tended to score lower than the other groups on all but the cognitive impairment subscale. Severity level analyses indicated that as severity of deficits increases, awareness of deficits decreases. This study found that although the GDS-30 is a good screening tool for depression in geriatric patients, it is not particularly useful in differentiating cognitive status group. Also, the GDS-15 was not found to be a good substitute for the GDS-30.

Early detection of Alzheimer's disease (AD) and related dementias in the elderly is critical for improving treatment methods and is a necessary component for improving public health interventions. One of the earliest and most common behavioral syndromes of AD is apathy and is associated with executive dysfunction. Apathy in AD is often misdiagnosed as depression due to an overlap in symptoms. Studies that have found depression to be associated with executive dysfunction have not always controlled for the presence of apathy. The Geriatric Depression Scale (GDS) is a widely used instrument designed to assess depression in the elderly. This study utilized the GDS and a set of standard neuropsychological instruments to investigate the relationship between apathy, depression, and executive functions in individuals with AD and related dementias. The first objective of this study was to determine if apathy has a greater impact on executive functions compared to depression in AD and related dementias. The second objective was to determine the effectiveness of the GDS as a screen for apathy. The results of the analyses did not support the hypotheses. However, exploratory analyses suggested a possible non-linear relationship with apathy and various levels of dementia severity. Exploratory analysis also suggested mean levels of endorsement for apathy varied by diagnosis. Further research is warranted to investigate this relationship and the GDS endorsement patterns for caregivers regarding their impression of the demented individual.