P3-013: Correlations between cognitive and behavioral measures of executive dysfunction in patients with mild Alzheimer’s disease

Abstract

In patients with moderate to severe Alzheimer's Disease the severity of executive cognitive dysfunction has been associated with the development of problem behavior and neuropsychiatric symptoms. Executive dysfunction has also been reported in patients with mild Alzheimer's disease but data is sparse and the correlation between executive cognitive impairment and dysexecutive behavior has to our knowledge not been investigated in this group. To investigate the prevalence of executive dysfunction in patients with mild Alzheimer's disease and to examine the relationships between two different approaches to measurement of executive dysfunction: Neuropsychological testing and behavioral evaluation. 52 patients fulfilling the NINCDS–ADRDA criteria for possible or probable Alzheimer's disease were included. All had mild AD (MMSE≥20) and were 60 years or above. Executive cognitive functions were assessed using: Modified Wisconsin Card Sorting, Trail Making Test Part B, Stroop Color/Word Interference, Verbal Fluency, Design Fluency and Verbal Abstraction. To obtain a global executive measure an index including all executive tests was constructed. Based on the performances of healthy controls cut off scores of 1.5 SD were defined for each test. Scores below were considered impaired. Behavioral changes associated with frontal dysfunction were assessed using the Frontal Behavioral Inventory (FBI), a 24–item structured interview with the patient's caregiver. The patients scored significantly lower than an aged matched control group on all executive cognitive tests. Mean score on the FBI was 10.1(SD: 6.7; range: 1–34 points). 50% of the patients scored 8 points or below. No significant correlations were found between the FBI–scores and the patients' performances on any of the executive tests. Patients with mild Alzheimer's Disease are significantly impaired on a wide number of executive cognitive tests when compared to healthy controls. The patients' caregivers report behavioral changes associated with executive dysfunction already at this stage. However, for most patients changes are very mild. At this early stage of the disease there is no significant correlation between impairment on executive cognitive measures and the presence of dysexecutive behavior.