Electroencephalography and computerised tomography in vascular and non-vascular dementia in old age

Protocol for the Prognosticating Delirium Recovery Outcomes Using Wakefulness and Sleep Electroencephalography (P-DROWS-E) study: a prospective observational study of delirium in elderly cardiac surgical patients

INTRODUCTION

Delirium is a potentially preventable disorder characterised by acute disturbances in attention and cognition with fluctuating severity. Postoperative delirium is associated with prolonged intensive care unit and hospital stay, cognitive decline and mortality. The development of biomarkers for tracking delirium could potentially aid in the early detection, mitigation and assessment of response to interventions. Because sleep disruption has been posited as a contributor to the development of this syndrome, expression of abnormal electroencephalography (EEG) patterns during sleep and wakefulness may be informative. Here we hypothesise that abnormal EEG patterns of sleep and wakefulness may serve as predictive and diagnostic markers for postoperative delirium. Such abnormal EEG patterns would mechanistically link disrupted thalamocortical connectivity to this important clinical syndrome.

METHODS AND ANALYSIS

P-DROWS-E (Prognosticating Delirium Recovery Outcomes Using Wakefulness and Sleep Electroencephalography) is a 220-patient prospective observational study. Patient eligibility criteria include those who are English-speaking, age 60 years or older and undergoing elective cardiac surgery requiring cardiopulmonary bypass. EEG acquisition will occur 1-2 nights preoperatively, intraoperatively, and up to 7 days postoperatively. Concurrent with EEG recordings, two times per day postoperative Confusion Assessment Method (CAM) evaluations will quantify the presence and severity of delirium. EEG slow wave activity, sleep spindle density and peak frequency of the posterior dominant rhythm will be quantified. Linear mixed-effects models will be used to evaluate the relationships between delirium severity/duration and EEG measures as a function of time.

ETHICS AND DISSEMINATION

P-DROWS-E is approved by the ethics board at Washington University in St. Louis. Recruitment began in October 2018. Dissemination plans include presentations at scientific conferences, scientific publications and mass media.

TRIAL REGISTRATION NUMBER

NCT03291626.

Neuroimaging markers of global cognition in early Alzheimer's disease: A magnetic resonance imaging-electroencephalography study

INTRODUCTION

Magnetic resonance imaging (MRI) and electroencephalography (EEG) are a promising means to an objectified assessment of cognitive impairment in Alzheimer's disease (AD). Individually, however, these modalities tend to lack precision in both AD diagnosis and AD staging. A joint MRI-EEG approach that combines structural with functional information has the potential to overcome these limitations.

MATERIALS AND METHODS

This cross-sectional study systematically investigated the link between MRI and EEG markers and the global cognitive status in early AD. We hypothesized that the joint modalities would identify cognitive deficits with higher accuracy than the individual modalities. In a cohort of 111 AD patients, we combined MRI measures of cortical thickness and regional brain volume with EEG measures of rhythmic activity, information processing and functional coupling in a generalized multiple regression model. Machine learning classification was used to evaluate the markers' utility in accurately separating the subjects according to their cognitive score.

RESULTS

We found that joint measures of temporal volume, cortical thickness, and EEG slowing were well associated with the cognitive status and explained 38.2% of ifs variation. The inclusion of the covariates age, sex, and education considerably improved the model. The joint markers separated the subjects with an accuracy of 84.7%, which was considerably higher than by using individual modalities.

CONCLUSIONS

These results suggest that including joint MRI-EEG markers may be beneficial in the diagnostic workup, thus allowing for adequate treatment. Further studies in larger populations, with a longitudinal design and validated against functional-metabolic imaging are warranted to confirm the results.

Multi-Infarct Dementia: A Historical Perspective

Background

Multi-infarct dementia (MID), a prominent subtype of vascular dementia (VaD), has only achieved recognition in the last 4 decades. Since its original description, the characterization, etiological understanding, and therapeutic direction of MID and other VaD subtypes has progressed at an astounding rate.

Summary

This paper divides the landmark discoveries and emergence of new research strategies for MID into decade-defining patterns so that a condensed picture of the total history of MID and its eventual inclusion as a VaD subtype emerges. This paper follows the first descriptive decade, a shift to a preventative focus, a renewed interest coinciding with timely advances in research technology, and a hopeful return to treatment possibilities for VaD.

Key Message

Concisely tracing the historical lineage of the modern understanding of MID, both as a singular entity and as part of the VaD con­stellation of disorders, provides a novel perspective on the foundation upon which future advances in combating vascular contributions to dementia will be based.

Does EEG (visual and quantitative) reflect mental impairment in subcortical vascular dementia?

The aim of this study was to determine if the results of visual and quantitative EEG (QEEG) parameters reveal a correlation with mental impairment in subcortical vascular dementia (SVD), one of the most frequent causes of cognitive impairment in the elderly. In SVD, like in Alzheimer's disease disturbances were found in cholinergic transmission. The cholinergic deficit as manifested in changes of synaptic potentials is reflected in EEG signals.

MATERIAL

31 patients with probable SVD (according to NINCDS-AIREN and T. Erkinjuntii's criteria) and mean age 72.3 yrs;(M--43%, F--57%) and 14 healthy control subjects with mean age of 72.3 yrs (M-57%, F-43%). According to the Mini Mental Scale Examination (MMSE) the SVD group was divided into two subgroups with mild and moderate dementia, their EEGs being recorded with a Medelec and Neuroscan 4.2 system. Visual EEG findings were classified with the use of eight-degree scale of pathological changes by the presence of slow waves. Then QEEGs were made. The following parameters were calculated: alpha/slow wave power ratios, the mean wave frequency in all and in some selected derivations.

RESULTS

A significant difference was found between QEEGs in SVD subgroups with mild and moderate dementia (p<0.05), but there was no significant difference between visual EEGs. A significant correlation between QEEG parameters such as alpha/slow wave ratio or mean wave frequency and mental impairment (according to MMSE results) was found (p<0.001), but there was no significant correlation between degree of EEG abnormalities in visual analysis and MMSE results.

CONCLUSION

Only QEEGs are correlated with mental impairment in SVD. Visual EEG technique as a less precise tool does not reflect the mental impairment in SVD due to cholinergic deficit.

Electroencephalogram in the dementia workup

Dementia is affecting an increasing proportion of the population in the developed world. It is important to reach a correct diagnosis of dementia, because this has implications on the treatment. The electroencephalogram (EEG) is, in general, not a sensitive test for detecting dementia and is not recommended in the standard workup of dementia. In spite of this, however, EEG is useful in patients with deteriorating mental status in whom dementia is suspected mainly to rule out delirium, depression, atypical complex partial seizures, and prion disease. An EEG also provides insight into the physiology of different dementia types. The EEG is most useful when interpreted within a well-defined clinical context, such as knowing the patient's degree of cognitive impairment. It is a noninvasive and inexpensive test, and the threshold should be low for ordering it. This article summarizes EEG findings with aging, different dementia types, and conditions masked as dementia.

EEG dynamics in patients with Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by cognitive and intellectual deficits and behavior disturbance. The electroencephalogram (EEG) has been used as a tool for diagnosing AD for several decades. The hallmark of EEG abnormalities in AD patients is a shift of the power spectrum to lower frequencies and a decrease in coherence of fast rhythms. These abnormalities are thought to be associated with functional disconnections among cortical areas resulting from death of cortical neurons, axonal pathology, cholinergic deficits, etc. This article reviews main findings of EEG abnormalities in AD patients obtained from conventional spectral analysis and nonlinear dynamical methods. In particular, nonlinear alterations in the EEG of AD patients, i.e. a decreased complexity of EEG patterns and reduced information transmission among cortical areas, and their clinical implications are discussed. For future studies, improvement of the accuracy of differential diagnosis and early detection of AD based on multimodal approaches, longitudinal studies on nonlinear dynamics of the EEG, drug effects on the EEG dynamics, and linear and nonlinear functional connectivity among cortical regions in AD are proposed to be investigated. EEG abnormalities of AD patients are characterized by slowed mean frequency, less complex activity, and reduced coherences among cortical regions. These abnormalities suggest that the EEG has utility as a valuable tool for differential and early diagnosis of AD.

Cognitive impairment after stroke: clinical determinants and its associations with long-term stroke outcomes

OBJECTIVES

To identify factors that were associated with cognitive impairment 3 months after stroke, and to examine the associations of cognitive impairment with stroke outcomes up to 4 years after stroke.

DESIGN

Observational study.

SETTING

Population-based stroke register.

PARTICIPANTS

Six hundred forty-five subjects with first-ever stroke, identified from the register.

MEASUREMENTS

Subjects were assessed for cognition using the Mini-Mental State Examination (MMSE) 3 months after stroke. Cognitively impaired subjects (MMSE <24, n = 248 (38%)) were compared with cognitively intact subjects (MMSE 24-30, n = 397) in terms of demographic details, stroke risk factors, laterality of stroke, and initial poststroke impairments. Outcome data collected at 1, 3, and 4 years poststroke included disability assessed by the Barthel Index (BI) and the Frenchay Activity Index, case fatality, and institutionalization.

RESULTS

Two hundred forty-eight (38%) of 645 subjects were cognitively impaired 3 months after stroke. Using multivariate analyses, cognitive impairment was associated with age of 75 and older (odds ratio (OR) = 2.5, 95% confidence interval (CI) = 1.5-4.2), ethnicity (Caribbean/African (OR = 1.9, 95% CI = 1.2-3.2) and Asian (OR = 3.4, 95% CI = 1.1-10.2), lower socioeconomic class (OR = 2.1, 95% CI = 1.3-3.3), left hemispheric lesion (OR = 1.6, 95% CI = 1.01-2.4), visual field defect (OR = 2.0, 95% CI = 1.2-3.2), and urinary incontinence (OR = 4.8, 95% CI = 3.1-7.3). Using multivariate analyses, cognitive impairment was associated with death or disability (BI <15) at 4 years after stroke (OR = 2.2, 95% CI = 1.1-4.5). In univariate analyses, it was also associated with higher institutionalization 4 years after stroke (P =.001).

CONCLUSIONS

Cognitive impairment is common 3 months after stroke and is independently associated with older age, ethnicity, lower social class, left hemispheric stroke, visual field defect, and urinary incontinence. It is associated with poor long-term outcomes, including survival and disability, up to 4 years after stroke. Because physical and cognitive impairments after stroke have independent prognostic implications, measures that evaluate both functions should be used in future studies of stroke outcome and in care of stroke patients.

Clinical neurophysiology using electroencephalography in geriatric psychiatry: neurobiologic implications and clinical utility

Electroencephalography (EEG) offers a unique contribution to the armamentarium of imaging technologies used in the evaluation of brain function. The primary clinical application of EEG is in the diagnosis of delirium, dementia, and epilepsy, which are frequently encountered in the practice of geropsychiatry. This review summarizes the principles behind generation of the EEG signal, its strengths and limitations as a technology, clinical indications for performing an EEG, the principles underlying quantitative EEG (QEEG), and how QEEG is allowing us to probe brain function and connectivity in new ways.

Electroencephalography and single photon emission computed tomography in dementia: a comparative study

A series of elderly patients with dementia of Alzheimer type (AD), multi-infarct dementia (MID) and functional (non-organic) psychiatric illness (major depressive disorder) were selected according to DSM-III-R criteria and received: a battery of cognitive tests, EEG and Single Photon Emission Computed Tomography (SPECT) using 99mTc HMPAO. The EEG and SPECT scans were examined independently of the clinical data. The former were divided into two abnormal categories, those showing AD type change and vascular change respectively, and a normal group. The SPECT scans were classified as follows: a SPECT rCBF pattern showing bilateral temporoparietal perfusion deficits (AD type); those showing single focal perfusion deficits or multiple areas of low perfusion in the cerebral cortex suggestive of ischaemic change (vascular type SPECT picture); a mixed AD/MID pattern; and those with normal scan findings. There were significant associations between clinical diagnosis, EEG rating and SPECT rCBF pattern, approximately three-quarters of AD and MID patients having the predicted EEG and scan changes. Normal EEG recordings were more common in the MID patients. The two tests agreed in about two-thirds of cases, with no consistent pattern apparent in the cases with divergent findings. Each test misclassified a minority of dementia patients, but in only one patient were both investigations normal. Almost half of the so called 'functionally ill' patients had abnormal rCBF changes, showing mainly vascular changes while one-fifth had abnormal EEGs.

Quantitative topographical EEG compared to FDG PET for classification of vascular and degenerative dementia

Quantitative topographical EEG was compared with regional glucose metabolism measured by PET with respect to the sensitivity in the classification of mild to moderate dementia. In 24 patients with probable Alzheimer's disease (DAT), 19 patients with vascular dementia (VD) and 15 age-matched healthy controls, global and regional EEG and PET data were analyzed. The metabolic ratio between typically affected and non-affected regions differentiated between DAT and VD (P < 0.001) as well as between DAT and normal controls (P < 0.001) even for the subgroup of mild dementia. In contrast to PET, global EEG changes were more sensitive than regional alterations for the classification into the respective groups. Relative theta power was most sensitive for the differentiation of demented patients irrespective of type of normal controls (P < 0.01), whereas OCC/FR alpha ratio (occipital divided by frontal power) separated between dementia types (P < 0.01) as well as between DAT and normals (P < 0.05). Additionally, EEG may help to grade severity especially in DAT. Combined use of EEG and PET was more discriminative and reached higher diagnostic specificity than each test individually. These results suggest that EEG and PET are complementary diagnostic procedures for the differentiation and classification of dementias.

Quantitative EEG analysis in early onset Alzheimer's disease: correlations with severity, clinical characteristics, visual EEG and CCT

We report EEG findings in 15 presenile Alzheimer patients (probable Alzheimer's disease according to NINCDS-ADRDA criteria) in relation to clinical characteristics. The quantitative EEG was analysed in terms of absolute band power while accounting for EOG and EMG artifacts, respectively. The degree of dementia is strongly reflected by an increase of power in the delta frequency band, accentuated on the left hemisphere, as well as decrease of alpha activity. Longer duration of disease is associated with a decrease of power in the alpha frequency band, earlier age at onset with an additional increase of power in the theta frequency band. Visual EEG evaluation correlates highly with the degree of dementia, in contrast to visually assessed CCT.

Quantitative EEG correlates of cognitive deterioration in the elderly

We report on the quantitative analysis of the EEG (QEEG), using the Neurometric method, in large samples of normal elderly; normal subjectively impaired elderly; patients with mild cognitive impairment; patients presenting with a continuum of primary cognitive deterioration from mild to moderately severe as measured by the Global Deterioration Scale (GDS), compatible with dementia of the Alzheimer's type (DAT). Neurometric QEEG measures were found to be a sensitive index of degree of cognitive impairment, especially reflected in increased absolute and relative power in the theta band, with delta increasing in later stages of deterioration. While these abnormalities were widespread, neither localized or lateralized, MANOVA's for GDS and relative power in theta reached highest significance in a bilateral temporo-parietal arc. A possible relationship between hippocampal dysfunction, cognitive deterioration, and theta abnormalities is discussed in relation to these findings. The results suggest that Neurometric QEEG features are sensitive to the earliest presence of subjective cognitive dysfunction and might be useful in the initial evaluation of patients with suspected dementia, as well as in estimating the degree of cognitive deterioration in DAT patients.

Clinical determinants of dementia related to stroke

Among 251 patients examined 3 months after the onset of acute ischemic stroke, we diagnosed dementia in 66 (26.3%) by using modified DSM-III-R criteria based on neuropsychological, neurological, functional, and psychiatric examinations. We used a logistic regression model to derive odds ratios (ORs) for clinical factors independently related to dementia in this cross-sectional sample. Dementia was significantly associated with age, education, and race. A history of prior stroke (OR = 2.7) and diabetes mellitus (OR = 2.6) was also independently related to dementia, but hypertension and cardiac disease were not. Stroke features associated with dementia included lacunar infarction compared with all other subtypes combined (OR = 2.7) and hemispheric laterality in relation to brainstem or cerebellar location. There was a predominance of dementia in patients with left-sided lesions (OR = 4.7), an effect not explained by aphasia. Dementia was especially common with infarctions in the left posterior cerebral and anterior cerebral artery territories. A major dominant hemispheral syndrome (reflecting size and laterality) was also independently associated with dementia (OR = 3.9). We suggest that dementia after ischemic stroke is a result of multiple independent factors, including both small subcortical and large cortical infarcts especially involving the left medial frontal and temporal regions, with additional contributions by demographic and vascular risk factors.

Clinical evaluation of the ICD-10 criteria for vascular dementia

The clinical feasibility of the ICD-10 criteria for subtypes of vascular dementia were examined in an investigation of 61 demented patients (74.4, SD 8.2 years) showing CT appearances of vascular lesions. Only 15 cases (24.6%) fulfilled the ICD-10 criteria of vascular dementia. Of these cases, 66.6% could adequately be classified in subtypes. The most frequent types of vascular dementia were multi-infarct dementia and subcortical vascular dementia. Our findings suggest that the ICD-10 criteria of vascular dementia are more selective than the classical 'ischaemic scales'.

Review of 18 years' experience of a diagnostic geriatric neurology referral service

From 1971 to 1989, 1446 cases were referred from Glasgow and the West of Scotland to the University Department of Geriatric Medicine for neurological diagnosis. In that time, the number increased from one per week to more than two per week, and the proportion from outside Glasgow from 2% to 24%. Eighty-seven per cent had CT scans and 8% electrophysiological studies. One third of patients stayed three days or less, and one third over a week. Cerebrovascular disease was diagnosed in 637 cases (44%), subdural haematoma or hygroma in 59 (4%), and intracranial tumour in 228 (16%), of which 26 (11%) were benign. In 104 cases (7%) no definite diagnosis was made. Management was changed in 402 of the 1446 cases (28%). In the 635 (44%) in whom a referring diagnosis was documented, this was not confirmed in 63%; diagnosis and/or management was changed in 80%. The proportions of referring diagnoses of subdural haematoma and intracranial tumour that were confirmed rose with time. The value of the service lay in the speed and ease of access to it, and the opportunities for teaching and learning it provided. The problems it posed were those of the transfer of ill patients, the distances sometimes necessary, and the need for high standards of communication.

Quantitative measurement of delta activity in Alzheimer's disease

Quantitative measurements of delta activity were made in 10 healthy elderly controls and 31 subjects with Alzheimer's disease. Delta activity did not discriminate between the healthy elderly controls and the early mild Alzheimer's disease subjects. However, delta activity was a significantly greater percentage of total EEG power in the moderate-to-advanced Alzheimer's subjects when compared to either the healthy controls or mild Alzheimer subjects. In the T3 and T4 electrodes, delta activity in the moderate-to-advanced Alzheimer subjects was 78.3% and 47.6% higher, respectively, than in control subjects. Furthermore, delta activity was an excellent predictor of dementia severity within the 31 subjects with Alzheimer's disease.

Topographic maps of brain electrical activity in primary degenerative dementia of the Alzheimer type and multiinfarct dementia

The topography of the electroencephalographic (EEG) pattern of ten patients with primary degenerative dementia of the Alzheimer type, ten multiinfarct dementia patients, and ten age-matched controls was compared during three different behavioral conditions: resting condition with eyes open (EO), memorizing a list of words (M), and recalling the same list of words (R). Results indicate that the alpha frequency band does not show significant changes. On the other hand, the theta band could be considered an important factor in the differential diagnosis of the primary degenerative dementia of the Alzheimer type, showing a higher power over right posterior regions in this group of patients compared with the multiinfarct dementia patients under different behavioral conditions.

Reliability, validity and follow-up of the EEG in senile dementia: sequelae of sequential measurement

In a longitudinal study, slowing of the EEG in SDAT patients and elderly controls is investigated using both visual and power spectral analyses. For this a reliability study in 20 SDAT patients is performed and results for intra-rater, inter-rater and test-retest reliability (in 24 h) are used in the selection of parameters. Next, the diagnostic efficacy of the chosen parameters for SDAT is confirmed in a validity study in 43 SDAT patients, 41 elderly non-organic psychiatric patients and 51 elderly normals. In the longitudinal study 78 of these subjects could be retested after 20 months. The parameter for visual analysis appeared to be superior in actually showing a progress of slowing of the EEG in 20/21 SDAT patients over time. The parameter for power spectral analysis was superior in measuring the more subtle processes in the normal elderly. Results of these studies are used to discuss some problems in the measurement of EEG in SDAT over time.

Brainstem auditory evoked potentials in patients with multi-infarct dementia and dementia of the Alzheimer type

Brainstem auditory evoked potentials (BAEPs) were recorded in 25 patients with multi-infarct dementia (MID) (mean age 71.2 years), 16 patients with dementia of the Alzheimer type (DAT) (mean age 70.6 years), and 34 normal subjects (mean age 69.1 years). Both MID and DAT patients showed significant prolonged interpeak latencies between waves I and V (I-V IPLs) compared to normal subjects (p less than .001 and p less than .01, respectively). In patients with MID, both I-III IPLs and III-V IPLs were significantly longer than those of normal subjects (p less than .01 and p less than .01 respectively). On the other hand, only III-V IPLs were significantly prolonged in patients with DAT (p less than .01). There were no significant differences between MID and DAT with regard to any of the IPLs. Present results suggest that the brainstem lesions are located in the auditory pathways in patients with MID and DAT. However, with BAEP measurements, we were not able to discriminate between patients with MID and DAT.

Multi-infarct dementia: a computed tomographic study

CT Scan of 30 patients with multi-infarct dementia (MID) were compared with age- and sex-matched controls. Infarcts were seen in 93% of MID cases and 10% of controls. A marked difference in the occurrence of white matter low attenuation was seen between the groups. All the parameters of cerebral atrophy studied showed a statistically significant correlation with the presence of dementia.

Computerized electroencephalography in the evaluation of early dementia

In elderly patients presenting to an ambulatory practice with complaints of cognitive disturbance, early dementia must be differentiated from depression. The present paper describes the application of standard electroencephalography and evoked potential testing (EEG/EP) and computerized electroencephalography with evoked potential mapping (CEEG/EPM) in the analysis of 64 elderly patients complaining of cognitive disturbance. Although previous reports have claimed a sensitivity level of up to 80% for EEG in demented patients, it appears that a lower sensitivity (37% for EEG alone and 61% for EEG/EP) may be expected at the time of early presentation according to the present study. No EEG/EP abnormalities were detected in patients with depression. In demented patients, CEEG/EPM was abnormal in 85% (46 of 54) of cases compared to 10% (1 of 10) of cases with depression. Specific information was obtained from EEG/EP studies that helped differentiate the various causes of dementia in three cases. In CEEG/EPM studies, a pattern of relative suppression of alpha activity or suppressed auditory P300 amplitude in the posterior parietal regions was observed in 11 or 23 (48%) patients with Alzheimer's disease and 2 of 31 (6%) patients with other forms of dementia. None of the depressed patients demonstrated such changes. Based on the present study, it appears that computerized techniques may hold promise as an adjunct to standard EEG evaluation of patients with mild cognitive change in whom diagnosis of dementia or depression is in doubt. Although standard EEG rarely demonstrates characteristic changes that may help differentiate causes of dementia, CEEG/EPM appears to demonstrate, on occasion, abnormalities in the posterior temporal and parietal regions in patients with a diagnosis of probable Alzheimer's disease and rarely in other forms of dementia or depression.

Progressive aphasia with right-sided extrapyramidal signs: another manifestation of localised cerebral atrophy

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Diagnostic efficacy of computerized spectral versus visual EEG analysis in elderly normal, demented and depressed subjects

Computerized spectral and visual EEG analyses were performed in 35 patients with Alzheimer's disease (AD) and compared to 23 patients with major depression and to 61 healthy elderly controls. In particular, we were interested in the diagnostic efficacy of these two techniques in the identification of cases of AD with only mild cognitive impairment (as measured by the Folstein Mini-Mental State score). For the computer analyzed data, in differentiating AD patients from controls, the spectral pooled parasagittal mean frequency was used. In comparing AD patients to depressed subjects, a combined parasagittal delta and theta spectral score was employed. Visual analysis criteria were based on the severity of generalized EEG abnormalities (with or without focal features). We found that spectral analysis afforded only modest advantages over visual EEG analysis in differentiating AD patients from elderly controls as well as from those with major depression. Since the degree of spectral and visual EEG abnormalities correlated with the severity of dementia, both tests more often correctly classified those AD patients with lower Folstein scores. Also, both tests identified primarily the same patients. We did not find the computer to be more sensitive than the eye in the identification of AD patients with mild impairment. However, computerized spectral data was derived from only 4 channels, while 16 channels and a longer recording time were used for visual analysis. In addition, some areas which have been reported to show EEG abnormalities in AD were not included in the computerized data.

EEG in the differential diagnosis between Alzheimer's disease and vascular dementia

Demented patients with Alzheimer's disease (AD) (n = 67), multi-infarct dementia (MID) (n = 77) and probable vascular dementia (PVD) (n = 45) were studied with electroencephalography (EEG). All patients underwent a routine EEG examination and quantitative EEG was recorded from 14 patients with AD, 20 with MID, and 12 with PVD. The patient groups did not differ in regard to sex, age, education, or degree of dementia. Diffuse abnormality of EEG increased in AD, while driving response to photic stimulation and the mean frequency of background activity decreased in all groups with increasing degree of dementia. In quantitative EEG, the percentage of alpha power decreased and those of theta and delta power increased relative to the degree of dementia. Focal abnormalities, and irritative (spikes and/or sharp waves) and slow wave paroxysms were more common in MID than in AD. Patients with different types of dementia did not differ significantly in regard to diffuse abnormality, occurrence of driving response, mean background frequency, or parameters of quantitative EEG. The mean frequency of background activity and the degree of diffuse abnormality correlated with central and cortical atrophy, white matter low attenuation seen on computed tomography, and with neuropsychological findings.

Differential diagnosis between Alzheimer's disease and vascular dementia: evaluation of common clinical methods

A prospective series of consecutively admitted demented patients were examined in order to evaluate the role of common clinical methods in the differential diagnosis between Alzheimer's disease (AD) and vascular dementia. Patients fulfilling the DSM-III criteria for vascular dementia were divided into multi-infarct dementia (MID) and probable vascular dementia (PVD), the latter including also cases with combined vascular and degenerative dementia. The series consisted of 68 patients with AD, 79 with MID and 46 with PVD. These groups did not differ in regard to sex, age or degree of dementia. Absence of cardio- and cerebrovascular diseases differentiated AD from MID and PVD. Also absence of corticospinal tract signs and gait disorders differentiated AD from MID and PVD and that of bulbar signs AD from MID. Infarcts and white matter low attenuation on CT differentiated MID and PVD from AD. Altogether 88.6% of the MID patients and 41.3% with PVD had brain infarct on CT, but only one with AD. Ischemic scores seemed also to be useful in the differential diagnosis between AD and vascular dementia. Quantitative neuropsychology, EEG, routine cerebrospinal fluid and other laboratory investigations, including serum glucose and plasma lipids, seem to be less valuable.

EEG dysfunction in geropsychiatry

Electro-clinical correlations are reported in 200 elderly patients admitted to a psychiatric ward of a general hospital. Normal EEG characteristics were generally associated with functional psychiatric disorder. Abnormal EEG features correlated with organic brain syndromes (O.B.S.). The diagnostic and pathogenetic considerations and restrictions of EEG foci, intermittent rhythmic delta activity (Irda) and diffuse EEG slowing are discussed. The informative value of EEG dysfunction in geropsychiatry is emphasised.

CT in the differential diagnosis between Alzheimer's disease and vascular dementia

A prospective series of consecutively admitted patients with Alzheimer's disease (AD) (n = 68), multi-infarct dementia (MID) (n = 79) and probable vascular dementia (PVD) (n = 46) were studied by CT of the head. In MID 88.6% and in PVD 41.3% of the patients had at least one brain infarct on CT, but only one patient (1.5%) with AD. White matter low attenuation (WMLA) also differentiated MID and PVD from AD, especially among patients aged 75 years or less, and with mild or moderate dementia. In all types, brain atrophy on CT had a positive correlation with the degree of dementia. Infarcts and WMLA on CT, but not brain atrophy seem to be of differential diagnostic value between vascular and degenerative dementia.

The EEG in the normal elderly: a contribution to the interpretation of aging and dementia

Forty-seven normal elderly, 16 normal subjects ranging from 40 to 60 years of age and 14 patients affected by primary dementia are studied. The EEG is recorded from different brain areas and analysed by FFT algorithm. Main results are: There is persistence of the regional distribution of the alpha frequency which is higher in occipital than in frontal leads in the normal elderly. Spectral composition in the same group keeps its typical profile with age. Alpha-dominant tracings form 68%. Values collected from the two hemispheres are similar. Therefore, no evidence is detected for a selective age effect on one side, either right or left. In the elderly group, a sex-linked difference is found. Women have less delta and more beta frequency. The opposite holds true in men. EEG slowing is typical of old age. However, in occipital leads the alpha frequency has an average of 9.46 Hz. Statistical comparison between the normal groups (middle aged vs. elderly) gives no significant results. Significant differences are seen when the normal elderly are compared with demented subjects. The data do not support the hypothesis of a continuum from aging to mental deterioration.

A longitudinal EEG study of mild senile dementia of Alzheimer type: changes at 1 year and at 2.5 years

This longitudinal study of resting EEGs compared patients with senile dementia of Alzheimer type (SDAT) and healthy controls at 3 times of testing over a 2.5 year period. Measures included the mean EEG frequency as well as the percentage of power in alpha, beta, theta, and delta frequency bands obtained from power spectral analysis. The values from occipital to vertex derivations were averaged for the left and right hemispheres. In healthy older adults delta increased, and both beta and mean frequency decreased over the study period; there was no significant change in theta or alpha. In the SDAT group, all 5 EEG measures changed significantly; there were increases in delta and theta, and decreases in beta, alpha and mean frequency. Theta percentage power distinguished between all 4 stages of dementia (control, mild, moderate and severe). Other EEG measures discriminated only at certain stages. In the mild stage of SDAT theta, beta and mean frequency were already different from control values. In the moderate stage, these differences persisted, and alpha became different. Delta was the last to change, and in the present small sample of those with severe SDAT the difference had not yet reached significance.

Examining the relationship between computed tomography and neuropsychological measures in normal and demented elderly

Correlational analysis of CT and neuropsychological measures in patients with dementia revealed more predictive relationships in degenerative and vascular subgroups that in a multi-aetiology group. Normal and dementia patients were then matched for age, sex and educational background, and analysed together. The ventricular/brain ratios of the bodies of the lateral ventricles and of the third ventricle correlated most highly with neuropsychologic performance. Canonical analysis revealed a correlation coefficient of 0.725 between the sets of CT and neuropsychological measures, which increased to 0.78 when a degenerative subgroup only was considered. Discriminant function analysis indicated that the combination of CT and neuropsychological measures was more powerful in discriminating normals from dementia patients than CT or neuropsychological measures alone.

Dementia of the Alzheimer type and multi-infarct dementia: a clinical description and diagnostic problems

Patients who had Alzheimer's disease-senile dementia of the Alzheimer type (AD/SDAT) or multi-infarct dementia (MID) were compared with a group of controls. Demented patients had approximately the same degree of dementia and the same duration of illness. The MID group had a significantly higher mean age than the AD/SDAT group. Sixty-three per cent of the AD/SDAT patients were free of other diseases, while 65 per cent of the MID patients had cardiovascular disease. Thirty per cent of the MID patients had a history of previous depression, while only 5 per cent of the AD/SDAT patients had had depression. At the time of the investigation, however, AD/SDAT patients showed significantly more signs of depression than the MID patients. Focal neurologic signs were found in 70 per cent of the MID patients and only 6 per cent of the AD/SDAT patients. The electrocardiogram was normal for every AD/SDAT patient, while 75 per cent of the MID patients had abnormal ECGs. Electroencephalography showed generalized slow frequencies in 79 per cent of the AD/SDAT patients and localized slow frequencies and abnormalities in 65 per cent of the MID patients. Computed tomography of the brain showed that MID patients had significantly greater dilation of the ventricular system, while cortical atrophy did not differ significantly among the three groups. Homovanillic acid in the cerebrospinal fluid was significantly lower in the AD/SDAT group as compared with controls.

Senile dementia of the Alzheimer type

The prevalence of severe dementia in the United States is about 1.3 million cases, of which at least 50 to 60% are of the Alzheimer type. Severe dementia of the Alzheimer type is found rarely in a clearly dominant pattern, although often one or more relatives are affected. Down's syndrome in adults is often associated with Alzheimer changes. The diagnosis is a clinicopathological one; there is a considerable error rate in the clinical diagnosis early in the course of the disease, especially in regard to dementia in depression. The differential diagnosis involves a great many disorders, including multi-infarct dementia, tumors, subdural hematomas, and others. Physiological aspects of Alzheimer's disease include a diffusely slow electroencephalogram, reduced cerebral blood flow, and particular patterns noted on positron emission tomographic scanning. The latter technique has also demonstrated that oxygen extraction is normal in Alzheimer's disease, thus excluding ischemia from possible pathogenetic factors. Morphological changes, that is, the presence of plaques and tangles, are widely distributed in neocortex, paleocortex, and many deep gray areas down through the pontine tegmentum, but largely exclude the basal ganglia, thalamus, and substantia nigra. Numerous plaques without neocortical tangles are found in many demented persons older than 75 years. A severe loss of large neocortical neurons is characteristic of the disease. The chemical nature of the paired helical filaments that make up the neurofibrillary tangle has not yet been ascertained. Neurons are markedly deficient in the basal forebrain nuclei, and this deficiency may account for the severe diminution of choline acetyltransferase and acetylcholine in the neocortex and paleocortex. Muscarinic cholinergic receptors are present in normal amounts. Norepinephrine is reduced in some cases, and somatostatin in most. Substance P is low in severe cases. The etiology of the disorder is unknown and the role of aluminum is disputed. Management of patients with Alzheimer's disease is difficult, and neuroleptics are to be used with great caution because of their side effects. Substrate therapy has not been effective; physostigmine improves memory but is not suitable for general use. Trophic factors, gangliosides, and aluminum chelation are being investigated for use in pharmacological intervention.

EEG and computed tomography in the investigation of patients with senile dementia

Fifty-six patients with senile dementia of Alzheimer type and 84 normal elderly people were examined by EEG and computed tomography. In discriminant function analysis of the computed tomography indexes the highest discriminant function coefficient was for width of the third ventricle. Using computed tomography, the groups were correctly classified for 84% of the subjects. In discriminant function analysis of the EEG variables the highest discriminant function coefficient was for dominant occipital rhythm; the groups were correctly classified for 86% of the subjects. In discriminant function analysis of the width of the third ventricle, an index of cortical atrophy, the dominant occipital rhythm, age and sex, the width of the third ventricle had the highest discriminant function coefficient; the groups were correctly classified for 90% of the subjects.

Computed tomography findings in senile dementia and normal aging

Computed tomography (CT) findings in 57 patients with senile dementia of Alzheimer type (SDAT), 19 patients with multi-infarct dementia and 85 controls of similar age and sex were studied. The SDAT patients differed from the controls of ventricular dilatation, frontal horn index, cella media index and the width of the third ventricle, and also in the index of cortical atrophy. Even the least severely demented SDAT patients differed from the controls. In the SDAT group with the increasing degree of intellectual impairment the ventricular dilatation increased, but cortical atrophy did not correlate with the psychological test score. The multi-infarct dementia patients differed from the controls in all CT variables including local changes. The SDAT patients had a more marked ventricular dilatation than the multi-infarct dementia patients. The multi-infarct dementia patients had more frequently local changes in SDAT patients. In the control group age correlated with ventricular dilatation, and the lower test scores correlated with cortical atrophy in the left temporal region.

Relation between central cerebral atrophy, memory defects and prolactin secretion

Concentrations of prolactin in cerebrospinal fluid (CSF) and in serum were determined from 26 neurological patients with or without minor central cerebral atrophy. Neuropsychological memory tests also were performed on these patients. Twenty-eight neurological patients with peripheral nervous lesions and without endocrine dysfunctions served as controls for prolactin levels. Patients with central cerebral atrophy had significant loss of recall capacity, though they did not differ significantly from the normal population in their intellectual performances. CSF and serum prolactin levels in the patients with central cerebral atrophy and/or memory defects did not differ from the values obtained in the patients without cerebral atrophy. Thus, prolactin levels do not appear to reflect either central cerebral atrophy or memory dysfunctions, most likely due to the minor degree of neuronal atrophy around the third ventricle that occurs in patients with these findings.

EEG findings in senile dementia and normal aging

EEG findings in 62 patients with senile dementia of alzheimer type (SDA), 22 patients with multi-infarct dementia (MID) and 90 controls of same age and sex were studied. The SDA patients differed significantly from the controls in EEG normality, over-all disturbance, dominant occipital, rhythm, accentuation of theta and delta, fluctuations in alertness, paroxysmal activity and H-reaction. Even the least severely affected SDA patients differed significantly from the controls in all EEG variables except paroxysmal activity. With increasing degree intellectual impairment in the SDA group the dominant occipital rhythm became slower. The MID group differed from the controls in all EEG parameters including asymmetric findings. The EEG findings of the SDA patients differed significantly from those of the MID patients only in asymmetric findings which were more common in the MID patients. 29% of the normal elderly people had EEG alterations, Abnormalities were mild. Asymmetric findings, mainly theta activity in left temporal region were common. H-reaction (occipital driving response greater than or equal to 18 c/s) was well preserved in the controls. EEG is valuable in differentiation of dementia patients from normal elderly people, but differentiation between MID and SDA is not reliable by using EEG, only.

Computerized axial tomography in chronic partial epilepsies

EEG and CAT studies were performed in 187 adult chronic epileptics. Acute convulsions, known tumor epilepsies, and seizures due to a rapidly advancing neurologic disease were excluded. Partial seizures of elementary and complex symptoms were nearly equally frequent. In 48 patients the etiology of the seizure disorder remained unknown. Among the verified etiologies residual brain damage were the most significant. In 10 cases the chronic seizure disorder was due to slowly growing brain tumors. CAT findings were normal in 86 patients (46%) and abnormal in 101 (54%). Localizing signs could be demonstrated by neuroradiologic and/or radionuclide tests in 15.7%, by CAT in 28.9%, by neurologic examination in 58.3%, and by EEG in 78.1%. Localized CAT-pathology showed no correlation to the types of partial seizures, whereas a significant correlation could be established with residual brain scars and tumors and with localized neurologic or EEG findings. Epilepsy starting after the age of 15 is more likely to be linked with CAT-pathology than with seizure disorders starting in childhood.