Flavio Nobili

Neuropsychiatric syndromes in dementia - Results from the European Alzheimer Disease Consortium: Part I

Background/Aims: The aim of this study was to identify neuropsychiatric subsyndromes of the Neuropsychiatric Inventory in a large sample of outpatients with Alzheimer’s disease (AD). Methods: Cross-sectional data of 2,354 patients with AD from 12 centres from the European Alzheimer’s Disease Consortium were collected. Principal component analysis was used for factor analysis. Results: The results showed the presence of 4 neuropsychiatric subsyndromes: hyperactivity, psychosis, affective symptoms and apathy. The subsyndrome apathy was the most common, occurring in almost 65% of the patients. Conclusion: This large study has provided additional robust evidence for the existence of neuropsychiatric subsyndromes in AD.

Mapping distributed sources of cortical rhythms in mild Alzheimer's disease. A multicentric EEG study

The study aimed at mapping (i) the distributed electroencephalographic (EEG) sources specific for mild Alzheimers disease (AD) compared to vascular dementia (VaD) or normal elderly people (Nold) and (ii) the distributed EEG sources sensitive to the mild AD at different stages of severity. Resting EEG (10-20 electrode montage) was recorded from 48 mild AD, 20 VaD, and 38 Nold subjects. Both AD and VaD patients had 24-17 of mini mental state examination (MMSE). EEG rhythms were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). Cortical EEG sources were modeled by low resolution brain electromagnetic tomography (LORETA). Regarding issue i, there was a decline of central, parietal, temporal, and limbic alpha 1 (low alpha) sources specific for mild AD group with respect to Nold and VaD groups. Furthermore, occipital alpha 1 sources showed a strong decline in mild AD compared to VaD group. Finally, distributed theta sources were largely abnormal in VaD but not in mild AD group. Regarding issue ii, there was a lower power of occipital alpha 1 sources in mild AD subgroup having more severe disease. Compared to previous field studies, this was the first investigation that illustrated the power spectrum profiles at the level of cortical (macroregions) EEG sources in mild AD patients having different severity of the disease with respect to VaD and normal subjects. Future studies should evaluate the clinical usefulness of this approach in early differential diagnosis, disease staging, and therapy monitoring.

EANM procedure guidelines for PET brain imaging using [ 18 F]FDG, version 2

These guidelines summarize the current views of the European Association of Nuclear Medicine Neuroimaging Committee (ENC). The purpose of the guidelines is to assist nuclear medicine practitioners in making recommendations, performing, interpreting, and reporting the results of fluorine-18 fluoro-2-deoxyglucose ([18F]FDG) PET imaging of the brain. The aim is to help achieve a high standard of FDG imaging, which will increase the diagnostic impact of this technique in neurological and psychiatric practice. The present document replaces a former version of the guidelines that were published in 2002 [1] and includes an update in the light of advances in PET technology, the introduction of hybrid PET/CT systems and the broadening clinical indications for FDG brain imaging. These guidelines are intended to present information specifically adapted for European practice. The information provided should be taken in the context of local conditions and regulations.

EANM procedure guidelines for brain neurotransmission SPECT using 123 I-labelled dopamine transporter ligands, version 2

These guidelines summarize the current views of the European Association of Nuclear Medicine Neuroimaging Committee (ENC). The aim of the guidelines is to assist nuclear medicine practitioners when making recommendations, performing, interpreting, and reporting the results of clinical dopamine transporter (DAT) single photon emission computed tomography (SPECT) studies using 123I-labelled radiopharmaceuticals. The aim is to achieve a high-quality standard of DAT SPECT imaging, which will increase the diagnostic impact of this technique in neurological practice. The present document is an update of the 2002 guidelines [1] and has been guided by the views of various national societies: the Task Group Neuro-Nuclear-Medicine of the German Society of Nuclear Medicine [2], a consensus statement of the imaging centres included in the “Kompetenznetz-Parkinson” sponsored by the German Federal Ministry of Education, and the Task Group of Neuro-Nuclear-Medicine of the French Society of Nuclear Medicine [3]. The guidelines reflect the individual experience of experts in European countries. The guidelines are intended to present information specifically adapted to European practice. The information provided should be taken in the context of local conditions and regulations.

Sources of Cortical Rhythms in Adults During Physiological Aging: A Multicentric EEG Study

This electroencephalographic (EEG) study tested whether cortical EEG rhythms (especially delta and alpha) show a progressive increasing or decreasing trend across physiological aging. To this aim, we analyzed the type of correlation (linear and nonlinear) between cortical EEG rhythms and age. Resting eyes‐closed EEG data were recorded in 108 young (Nyoung; age range: 18–50 years, mean age 27.3 ± 7.3 SD) and 107 elderly (Nold; age range: 51–85 years, mean age 67.3 ± 9.2 SD) subjects. The EEG rhythms of interest were delta (2–4 Hz), theta (4–8 Hz), alpha 1 (8–10.5 Hz), alpha 2 (10.5–13 Hz), beta 1 (13–20 Hz), and beta 2 (20–30 Hz). EEG cortical sources were estimated by low‐resolution brain electromagnetic tomography (LORETA). Statistical results showed that delta sources in the occipital area had significantly less magnitude in Nold compared to Nyoung subjects. Similarly, alpha 1 and alpha 2 sources in the parietal, occipital, temporal, and limbic areas had significantly less magnitude in Nold compared to Nyoung subjects. These nine EEG sources were given as input for evaluating the type (linear, exponential, logarithmic, and power) of correlation with age. When subjects were considered as a single group there was a significant linear correlation of age with the magnitude of delta sources in the occipital area and of alpha 1 sources in occipital and limbic areas. The same was true for alpha 2 sources in the parietal, occipital, temporal, and limbic areas. In general, the EEG sources showing significant linear correlation with age also supported a nonlinear correlation with age. These results suggest that the occipital delta and posterior cortical alpha rhythms decrease in magnitude during physiological aging with both linear and nonlinear trends. In conclusion, this new methodological approach holds promise for the prediction of dementia in mild cognitive impairment by regional source rather than surface EEG data and by both linear and nonlinear predictors. Hum Brain Mapp, 2005.

Diagnostic criteria for apathy in clinical practice.

Apathy is an important and distressing behavioural symptom in Alzheimers disease and in various neuropsychiatric disorders. Recently, diagnostic criteria for apathy have been proposed.

Consistency of Neuropsychiatric Syndromes across Dementias: Results from the European Alzheimer Disease Consortium

Background/Aims: The aim of this study was to determine the consistency of neuropsychiatric subsyndromes of the Neuropsychiatric Inventory across several clinical and demographic subgroups (e.g. dementia subtypes, dementia severity, medication use, age and gender) in a large sample of outpatients with dementia. Methods: Cross-sectional data of 2,808 patients with dementia from 12 centres from the European Alzheimer’s Disease Consortium were collected. Principal component analysis was used for factor analysis. Subanalyses were performed for dementia subtypes, dementia severity, medication use, age and gender. Results: The results showed the relatively consistent presence of the 4 neuropsychiatric subsyndromes ‘hyperactivity’, ‘psychosis’, ‘affective symptoms’ and ‘apathy’ across the subanalyses. The factor structure was not dependent on dementia subtypes, age and gender but was dependent on dementia severity and cholinesterase use. The factors hyperactivity and affective symptoms were present in all subanalyses, but the presence of the factors apathy and psychosis was dependent on use of cholinesterase inhibitors and dementia severity, respectively. Conclusion: The present study provided evidence of the relative consistency of neuropsychiatric subsyndromes across dementia subtypes, age and gender, thereby stressing the importance of thinking about neuropsychiatric subsyndromes instead of separate symptoms. However, the subsyndromes apathy and psychosis were dependent on use of cholinesterase inhibitors and dementia severity.

Fronto-parietal coupling of brain rhythms in mild cognitive impairment: A multicentric EEG study

Electroencephalographic (EEG) data were recorded in 69 normal elderly (Nold), 88 mild cognitive impairment (MCI), and 109 mild Alzheimers disease (AD) subjects at rest condition, to test whether the fronto-parietal coupling of EEG rhythms is in line with the hypothesis that MCI can be considered as a pre-clinical stage of the disease at group level. Functional coupling was estimated by synchronization likelihood of Laplacian-transformed EEG data at electrode pairs, which accounts for linear and non-linear components of that coupling. Cortical rhythms of interest were delta (2-4Hz), theta (4-8Hz), alpha 1 (8-10.5Hz), alpha 2 (10.5-13Hz), beta 1 (13-20Hz), beta 2 (20-30Hz), and gamma (30-40Hz). Compared to the Nold subjects, the AD patients presented a marked reduction of the synchronization likelihood (delta to gamma) at both fronto-parietal and inter-hemispherical (delta to beta 2) electrodes. As a main result, alpha 1 synchronization likelihood progressively decreased across Nold, MCI, and mild AD subjects at midline (Fz-Pz) and right (F4-P4) fronto-parietal electrodes. The same was true for the delta synchronization likelihood at right fronto-parietal electrodes (F4-P4). For these EEG bands, the synchronization likelihood correlated with global cognitive status as measured by the Mini Mental State Evaluation. The present results suggest that at group level, fronto-parietal coupling of the delta and alpha rhythms progressively becomes abnormal though MCI and mild AD. Future longitudinal research should evaluate whether the present EEG approach is able to predict the cognitive decline in individual MCI subjects.

Regional cerebral blood flow in chronic hypertension. A correlative study.

BACKGROUND AND PURPOSE Cerebral hypoperfusion has occasionally been reported during essential hypertension. We explored regional cerebral blood flow in a large series of neurologically asymptomatic hypertensive patients to determine relations among cerebral blood flow, concomitant main vascular risk factors, and the most common signs of end-organ damage. METHODS Regional cerebral blood flow was measured by the 133Xe inhalation method in 101 hypertensive patients without clinically apparent central nervous system involvement, including 39 mild to moderate untreated and 62 mild to severe treated patients. RESULTS Compared with age- and sex-matched normal control subjects, cerebral blood flow was significantly reduced in untreated hypertensive patients (P < .01) and to a lesser extent in treated patients (P = .047). Both regional and global cerebral blood flow reductions were observed in approximately one third of patients in both groups. Analysis of variance failed to show significant correlations between cerebral blood flow and total cholesterol concentration, mean arterial blood pressure, duration of disease, or the presence of retinopathy or left ventricular hypertrophy. In the treated group, the quality of control of hypertension significantly influenced both global cerebral blood flow (P = .007) and cerebrovascular resistance (P < .0001). CONCLUSIONS Focal or diffuse cerebral hypoperfusion is present even in neurologically asymptomatic hypertensive patients, especially when untreated; good control of blood pressure may preserve cerebral perfusion and reduce cerebrovascular resistance. Regional cerebral blood flow examination represents a relatively simple and low-cost technique to explore the perfusional condition of the brain, one of the main target organs of hypertensive disease.

Abnormal fronto-parietal coupling of brain rhythms in mild Alzheimer's disease: a multicentric EEG study

Cholinergic deafferentation/recovery in rats mainly impinges on the fronto‐parietal coupling of brain rhythms [D. P. Holschneider et al. (1999) Exp. Brain Res., 126, 270–280]. Is this reflected by the functional coupling of fronto‐parietal cortical rhythms at an early stage of Alzheimers disease (mild AD)? Resting electroencephalographic (EEG) rhythms were studied in 82 patients with mild AD and in control subjects, such as 41 normal elderly (Nold) subjects and 25 patients with vascular dementia (VaD). Patients with AD and VaD had similar mini‐mental state evaluation scores of 17–24. The functional coupling was estimated by means of the synchronization likelihood (SL) of the EEG data at electrode pairs, accounting for linear and non‐linear components of that coupling. Cortical rhythms of interest were delta (2–4 Hz), theta (4–8 Hz), alpha (1 8–10.5 Hz), alpha 2 (10.5–13 Hz), beta 1 (13–20 Hz), beta 2 (20–30 Hz) and gamma (30–40 Hz). A preliminary data analysis (Nold) showed that surface Laplacian transformation of the EEG data reduced the values of SL, possibly because of the reduction of influences due to head volume conduction. Therefore, the final analysis was performed on Laplacian‐transformed EEG data. The SL was dominant at alpha 1 band in all groups. Compared with the Nold subjects, patients with VaD and mild AD presented a marked reduction of SL at both fronto‐parietal (delta–alpha) and inter‐hemispherical (delta–beta) electrode pairs. The feature distinguishing the patients with mild AD with respect to patients with VaD groups was a more prominent reduction of fronto‐parietal alpha 1 SL. These results suggest that mild AD is characterized by an abnormal fronto‐parietal coupling of the dominant human cortical rhythm at 8–10.5 Hz.