Latchezar Traykov

OBJECTIVE: To investigate whether patients diagnosed with amnestic mild cognitive impairment (MCI) have also impairment in attention/executive functions, and therefore to clarify whether all subcomponents of executive control are equally affected in MCI. BACKGROUND: MCI refers to the transitional state between normal aging and dementia. Amnestic MCI is characterized by impaired episodic memory, although subtle impairment of executive functions has been noted on neuropsychologic tests. METHODS: We investigated 20 MCI patients and 20 normal controls using episodic memory, attention/executive functions, language, and praxis tests. RESULTS: MCI patients had significantly lower scores on all measures of the Free and Cued Selective Reminding Test (P<0.05 to 0.01) than controls. Furthermore, MCI had a greater number of perseverations (P<0.01) on Modified Card Sorting Test and the lowest performance on the Stroop Test (P<0.02). CONCLUSIONS: Our findings showed impairment in episodic memory performance in MCI as compared with that of controls. In addition, MCI patients had problems with response inhibition, switching, and cognitive flexibility, which encompass various aspects of executive functions. This suggests that MCI may be identified by using a more detailed procedure for the assessment of cognitive decline than the evaluation of memory alone.

Several studies have evaluated executive function in depressed patients, and the results vary from significant impairment relative to controls to virtually intact performances. To better comprehend executive impairment in elderly patients with major unipolar depression, the performance of 21 elderly depressed patients was compared with that of 19 elderly normal controls on executive tasks. The relationships between memory deficits and depression severity and between memory deficits and executive dysfunction were also examined. Depressed patients' performance was significantly worse than that of controls on almost all executive tasks. Their score for logical memory was significantly correlated with that for several executive tasks. Executive performance was also correlated with depression severity. Unipolar depressed patients present executive deficits. Memory failure in these patients may reflect impairment in retrieval processes, which in turn depends on executive function. Executive deficits are associated with depression severity. These results may be useful in the differential diagnosis between depression and early Alzheimer's disease.

To further clarify the cognitive syndrome in subcortical vascular dementia (VaD), we investigated 20 patients with early-stage VaD as compared with 30 patients with Alzheimer's disease (AD) and 22 normal controls using episodic memory, attention/executive function and language tests. The patient groups were closely matched in terms of age, education and severity of dementia. The VaD patients had a significantly better free recall, cued recall and recognition memory than AD patients, the recognition being within normal limits in VaD. In addition, VaD patients had a greater number of perseverative errors during the Modified Card Sorting test, while AD patients exhibited more perseverations of semantic fluency. The results of retrieval deficit syndrome and increased number of perseverations during tasks sensitive to frontal lobe function are in agreement with the studies emphasizing the importance of frontal dysfunction in subcortical VaD. These findings are relevant for the early diagnosis of VaD and might be useful in the differential diagnosis with AD.

OBJECTIVE: To investigate the relationships between cognitive impairment and apathy in patients with early Huntington's disease (HD) and to further explore the influence of depression on the outcome of cognitive changes associated with apathy. METHODS: We included 36 early HD patients, among them 20 were apathetic (HDA) and 16 were not (HDnA). The two groups were matched by age, education and severity of disease. Cognitive functions were evaluated by a comprehensive neuropsychological battery that measures memory, attention, executive function, language and visuospatial abilities. RESULTS: The HDA patients had significantly lower scores on memory, attention and executive function tests when compared with the HDnA patients (p values <0.05). We compared the performance of patients with (50%) and without depression on cognitive tasks and showed that depression per se did not influence performance. Finally, the results demonstrate that interactions between apathy and motor disturbance have a significant effect on cognitive impairment in HD. DISCUSSION: The presence of apathy is associated with more severe deficits of attention, executive function and episodic memory in early HD patients. Furthermore, the findings suggest that depression has little or no effect on cognitive deficits. Finally, apathy increased in parallel with both motor and cognitive dysfunction.