The quality of reproduction of the haptic stimuli and the theta-power changes indicate a cortical dysfunction and deficits in somatosensory integration processing of the right parietal cortex in AN patients even after weight gain.

Cognitive decline is known to be associated with both increased theta power over frontal regions and hippocampal atrophy. The aim of this study was to reveal the relation between these parameters in groups with mild dementia, mild cognitive impairment, and healthy control subjects. The authors examined a preliminary randomly selected sample of 39 right-handed subjects joining the Leipzig Longitudinal Study of the Aged, consisting of 17 normal elderly subjects, 12 patients with mild cognitive impairment, and 10 patients with mild dementia assessed by Clinical Dementia Rating. All subjects were between 75 and 85 years old (mean age, 78 years; standard deviation, 2.78 years) and underwent EEG and brain MRI. Mean spectral power densities were calculated, and hippocampal body volume was measured. Significant negative linear correlations between theta power over frontal regions and hippocampal volumes were found. The results support the assumption about a relationship between hippocampal atrophy and theta power, and may be helpful for a better understanding of the course of Alzheimer's disease.

The aim of this study was to investigate spectral EEG theta-power during perceptive-cognitive demands in age-homogeneous groups of subjects with mild cognitive impairment (MCI), mild dementia (MDE), and a healthy control (CO) group. The present study includes 51 subjects (23 males, 28 females). We used the scales of the CDR (clinical dementia rating) to assign the subjects to the different groups. EEG data were collected during 10 minutes rest condition with eyes closed and during haptic perception test. The quality of the haptic reproductions differed significantly between CO and MCI, as well as between CO and MDE. The statistical comparison between EEG theta-power under rest condition and theta-power during haptic tasks revealed a significant decrease in theta-power during haptic tasks in all three groups over parieto-occipital regions. During haptic tasks, the theta-power was significantly different between CO and MDE over occipital regions and over parieto-temporal regions. A significant difference between CO and MCI was only revealed over right occipital regions (O2). Spectral theta-power during haptic tasks is a suitable measure to distinguish healthy subjects (CO) from patients with MCI respectively MDE. The results show that haptic tasks are sensitive to early perceptive-cognitive and functional deficits in patients with MCI.

The capacitive strain of the right PC is substantially stronger in right side tasks with the consequence that the functionally disturbed right PC of AN patients cannot provide enough processing resources.