ABSTRACT
OBJECTIVE: The aim of this study was to investigate whether different types of visuoconstructional abilities are useful to distinguish individuals with mild cognitive impairment (MCI) and Alzheimer's disease (AD) from healthy controls (HCs). METHOD: We selected 20 patients with MCI and 14 with AD diagnosis based on standard criteria. The neuropsychological performance of MCI and AD groups were compared with that of a group of 11 HCs using a standard neuropsychological battery and visuoconstructional tasks that differed difficulty and type of implicated skills (graphomotor vs. non-graphomotor): two-dimensional (Clock Drawing Test, CDT; Block Design, BD; and Visual Puzzles, VP) and three-dimensional Block Construction (TBC). RESULTS: AD group scored significantly lower than HCs in BD, VP and TBC tasks, but no significant differences were found between HCs and MCI. CDT (copy condition) scores did not differ significantly among the groups. The receiver operating characteristic analysis showed that BD [sensitivity (se) = .85, specificity (sp) = .90, Youden index (J) = .76], VP (se = .78 and sp = .72, J = .51) and TBC (se = .71, sp = 100, J = .71) were accurate tasks to discriminate between AD and HCs. Moreover, BD tasks (se = .85, sp = .70, J = .55) and TBC (se = .71, sp = .80, J = .51) showed fair accuracy to differentiate between MCI and AD groups. CONCLUSIONS: These findings indicate that non-graphomotor visuoconstructional tasks are already impaired in the early stages of AD, but are preserved in MCI individuals when compared with HCs.
Subject(s)
Alzheimer Disease , Cognitive Dysfunction , Alzheimer Disease/complications , Alzheimer Disease/diagnosis , Cognitive Dysfunction/diagnosis , Humans , Neuropsychological Tests , ROC Curve , Sensitivity and SpecificityABSTRACT
Recent studies have demonstrated that nondemented patients with Parkinson's disease with visual hallucinations had lower scores on frontal-executive tasks than parkinsonian patients without hallucinations, most likely due to defective cholinergic circuitry. The aim of the present study is to investigate whether development of visual hallucinations in patients with Alzheimer's disease may also be related to more severe frontal dysfunctions. In the present study, 36 patients were included who were affected by probable Alzheimer's disease (18 with visual hallucinations and 18 without) and 38 patients affected by idiopathic Parkinson's disease (19 with visual hallucinations and 19 without). Patients completed a neuropsychological test battery and a short questionnaire to collect information about hallucination types and features. Multivariate analysis showed that patients with Alzheimer's disease scored significantly lower than patients with Parkinson's disease and that patients with hallucinations scored significantly lower than patients without hallucinations. Within both the Alzheimer's disease group and the Parkinson's disease group, patients with visual hallucinations scored significantly lower than patients without visual hallucinations, particularly on tests evaluating frontal-executive functions. These results demonstrate that patients with visual hallucinations show a significant impairment on tests tapping frontal-executive functions in Alzheimer's disease, as previously demonstrated (and verified here) in Parkinson's disease. On this basis it seems likely that analogous cognitive mechanisms underlie development of visual hallucinations in both degenerative diseases. Moreover, we may speculate that a defective circuitry of the prefrontal cortex is crucial for the genesis of hallucinations.
Subject(s)
Humans , Alzheimer Disease , Hallucinations , Parkinson Disease , Prefrontal Cortex , Neuropsychological Tests , Surveys and QuestionnairesABSTRACT
Recent studies have demonstrated that nondemented patients with Parkinson's disease with visual hallucinations had lower scores on frontal-executive tasks than parkinsonian patients without hallucinations, most likely due to defective cholinergic circuitry. The aim of the present study is to investigate whether development of visual hallucinations in patients with Alzheimer's disease may also be related to more severe frontal dysfunctions. In the present study, 36 patients were included who were affected by probable Alzheimer's disease (18 with visual hallucinations and 18 without) and 38 patients affected by idiopathic Parkinson's disease (19 with visual hallucinations and 19 without). Patients completed a neuropsychological test battery and a short questionnaire to collect information about hallucination types and features. Multivariate analysis showed that patients with Alzheimer's disease scored significantly lower than patients with Parkinson's disease and that patients with hallucinations scored significantly lower than patients without hallucinations. Within both the Alzheimer's disease group and the Parkinson's disease group, patients with visual hallucinations scored significantly lower than patients without visual hallucinations, particularly on tests evaluating frontal-executive functions. These results demonstrate that patients with visual hallucinations show a significant impairment on tests tapping frontal-executive functions in Alzheimer's disease, as previously demonstrated (and verified here) in Parkinson's disease. On this basis it seems likely that analogous cognitive mechanisms underlie development of visual hallucinations in both degenerative diseases. Moreover, we may speculate that a defective circuitry of the prefrontal cortex is crucial for the genesis of hallucinations.(AU)