Cognitive and anatomical correlates of anosognosia in amnestic mild cognitive impairment and early-stage Alzheimer's disease.

BACKGROUND: Anosognosia is a common feature in Alzheimer's disease (AD). The brain substrates of anosognosia are not fully understood, and less is known about the cognitive substrates of anosognosia in prodromal and early stages of AD. METHODS: Fourty-seven patients with amnestic-type mild cognitive impairment (aMCI) (n = 26) and early-stage AD (n = 21) were included, and Clinical Insight Rating Scale and Anosognosia Questionnaire for Dementia (AQ-D) were used to assess anosognosia. A detailed neuropsychological battery was administered; each patient underwent a structural magnetic resonance imaging (MRI). Correlation between anosognosia and performance in individual cognitive domains as well as correlation between anosognosia and cortical thickness values in regions of interest were assessed. RESULTS: Performance of the anosognosic patients in Digit Ordering Test (DOT), Digit Span Backwards, and Clock Drawing Test (CDT) was significantly worse compared to non-anosognosic patients in the total study population and in the aMCI subgroup but not in AD group. AQ-D scores negatively correlated with Mini-Mental State Examination (MMSE), California Verbal Learning Test (CVLT), Digit Span Backwards and CDT scores in total group and MMSE, CVLT, DOT, and Digit Span Backwards scores in the aMCI group. No significant correlations were found between cortical thickness measurements and AQ-D scores in any of the patient populations. CONCLUSIONS: Anosognosia was associated with episodic memory, working memory, and executive functions in the total population and aMCI group, but no association was found in early-stage AD patients. Anosognosia in the early stages of AD may be related with non-structural changes such as hypoconnectivity rather than structural changes.

The Relationship of White Matter Hyperintensities with Depressive Symptoms and Daily Living Activities in Early-Stage Alzheimer's Disease Patients.

INTRODUCTION: Cerebral white matter hyperintensities (WMHs) detected on magnetic resonance imaging scans are frequently seen in both Alzheimer's disease (AD) and depression patients and believed to play an important role in cognition and mood. Depressive symptoms and depression may accompany AD in all stages of the disease. The aim of the study was to evaluate the relationship of regional WMHs with depressive symptoms, cognitive status, medial temporal lobe atrophy, and daily living activities in early-stage AD patients. METHOD: Forty-five patients with very mild or mild AD were examined. All subjects underwent MRI and were assessed by the Geriatric Depression Scale (GDS) and the Addenbrooke's Cognitive Examination-Revised (ACE-R) for the evaluation of depressive symptom severity and cognitive status, respectively. The patients were divided into two groups based on the selected cut-off point in the GDS. CDR sum of the boxes (CDR-sb) scores were calculated as a measure of activities of daily living (ADLs). MRI T2-FLAIR slices were used to rate the white-matter lesions according to the Age-Related White Matter Changes Rating Scale, assessing the WMHs in frontal, parietooccipital, temporal, infratentorial and basal ganglia areas individually. Medial temporal lobe atrophy was assessed with high-resolution T1 images using visual rating scale. RESULTS: In the depressive group, frontal WMH scores were found to be higher than in the non-depressive group (p=0.006). ACE-r, CDR-sb and medial temporal lobe atrophy scores did not differ among the groups. CDR-sb scores showed a significant correlation with frontal WMH scores (left frontal WMH r=0.439, p=0.003, right frontal AMH r=0.459, p=0.001). Linear regression models revealed the effect of WMHs on depressive symptoms among the other factors including age, functionality and atrophy in the medial temporal areas. DISCUSSION: Our findings underscore the potential role of regional, particularly frontal AMHs in depressive symptoms and functionality of the early AD patients.