Executive function subdomains are associated with post-stroke functional outcome and permanent institutionalization.

BACKGROUND AND PURPOSE: Impairment of executive functions (EFs) is a common cognitive symptom post-stroke and affects independence in daily activities. Previous studies have often relied on brief cognitive tests not fully considering the wide spectrum of EF subdomains. A detailed assessment of EFs was used to examine which of the subdomains and tests have the strongest predictive value on post-stroke functional outcome and institutionalization in long-term follow-up. METHODS: A subsample of 62 patients from the Helsinki Stroke Aging Memory Study was evaluated with a battery of seven neuropsychological EF tests 3 months post-stroke and compared to 39 healthy control subjects. Functional impairment was evaluated with the modified Rankin Scale (mRS) and Instrumental Activities of Daily Living (IADL) scale at 3 months, and with the mRS at 15 months post-stroke. Institutionalization was reviewed from the national registers of permanent hospital admissions in up to 21-year follow-up. RESULTS: The stroke group performed more poorly than the control group in multiple EF tests. Tests of inhibition, set shifting, initiation, strategy formation and processing speed were associated with the mRS and IADL scale in stroke patients. EF subdomain scores of inhibition, set shifting and processing speed were associated with functional outcome. In addition, inhibition was associated with the risk for earlier institutionalization. CONCLUSIONS: Executive function was strongly associated with post-stroke functional impairment. In follow-up, poor inhibition was related to earlier permanent institutionalization. The results suggest the prognostic value of EF subdomains after stroke.

Spatial phase sensitivity of complex cells in primary visual cortex depends on stimulus contrast.

Neurons in primary visual cortex are classified as simple, which are phase sensitive, or complex, which are significantly less phase sensitive. Previously, we have used drifting gratings to show that the phase sensitivity of complex cells increases at low contrast and after contrast adaptation while that of simple cells remains the same at all contrasts (Cloherty SL, Ibbotson MR. J Neurophysiol 113: 434-444, 2015; Crowder NA, van Kleef J, Dreher B, Ibbotson MR. J Neurophysiol 98: 1155-1166, 2007; van Kleef JP, Cloherty SL, Ibbotson MR. J Physiol 588: 3457-3470, 2010). However, drifting gratings confound the influence of spatial and temporal summation, so here we have stimulated complex cells with gratings that are spatially stationary but continuously reverse the polarity of the contrast over time (contrast-reversing gratings). By varying the spatial phase and contrast of the gratings we aimed to establish whether the contrast-dependent phase sensitivity of complex cells results from changes in spatial or temporal processing or both. We found that most of the increase in phase sensitivity at low contrasts could be attributed to changes in the spatial phase sensitivities of complex cells. However, at low contrasts the complex cells did not develop the spatiotemporal response characteristics of simple cells, in which paired response peaks occur 180° out of phase in time and space. Complex cells that increased their spatial phase sensitivity at low contrasts were significantly overrepresented in the supragranular layers of cortex. We conclude that complex cells in supragranular layers of cat cortex have dynamic spatial summation properties and that the mechanisms underlying complex cell receptive fields differ between cortical layers.

Post-stroke cognitive impairment is common even after successful clinical recovery.

BACKGROUND AND PURPOSE: Cognitive impairment is common after stroke, but the prevalence and long-term significance of the diverse neuropsychological deficits on functional outcome are still not well known. The frequency and prognostic value of domain-specific cognitive impairments were investigated in a large cohort of ischaemic stroke patients. METHODS: Consecutive patients (n = 409), aged 55-85 years, from the acute stroke unit of the Helsinki University Hospital, Finland, were evaluated with extensive clinical and neuropsychological assessments 3 months post-stroke. Impairments within nine cognitive domains were determined according to age-appropriate normative data from a random healthy population. Functional disability was evaluated with the modified Rankin scale (mRS) 3 and 15 months post-stroke. RESULTS: In all, 83% patients showed impairment in at least one cognitive domain, whereas 50% patients were impaired in multiple (≥3) domains. In cases with excellent clinical recovery at 3 months (mRS = 0-1, no disability), the occurrence of any cognitive impairment was 71%. Memory, visuoconstructional and executive functions were most commonly impaired. A substantially smaller proportion of patients scored below the conventional or more stringent cut-offs in the Mini-Mental State Examination (MMSE). Domain-specific cognitive impairments were associated with functional dependence at 15 months regardless of stroke severity and other confounders. CONCLUSIONS: Cognitive impairment as evaluated with a comprehensive neuropsychological assessment is prevalent in stroke survivors even with successful clinical recovery. Typically multiple domains and complex cognitive abilities are affected. MMSE is not sensitive in detecting these symptoms. Post-stroke cognitive impairment is strongly related to poor functional outcome.

The feasibility of existing JADAS10 cut-off values in clinical practice: a study of data from The Finnish Rheumatology Quality Register.

BACKGROUND: The ten-joint juvenile arthritis disease activity score (JADAS10) is designed to measure the level of disease activity in non-systemic juvenile idiopathic arthritis by providing a single numeric score. The clinical JADAS10 (cJADAS10) is a modification of the JADAS10 that excludes erythrocyte sedimentation rate (ESR). Three different sets of JADAS10/cJADAS10 cut-offs for disease activity states have been published, i.e., the Backström, Consolaro, and Trincianti cut-offs. The objective of this study was to investigate the performance of existing JADAS10 cut-offs in real-life settings using patient data from The Finnish Rheumatology Quality Register (FinRheuma). METHODS: Data were collected from the FinRheuma register. The proportion of patients with an active joint count (AJC) above zero when classified as being in clinically inactive disease (CID) or low disease activity (LDA) groups according to existing JADAS10/cJADAS10 cut-off levels were analyzed. RESULTS: A significantly larger proportion of the patients classified as being in CID had an AJC > 0 when using the JADAS10/cJADAS10 cut-offs by Trincianti et al. compared to those for the other cut-offs. In the LDA group, a significantly larger proportion of the polyarticular patients (35%/29%) had an AJC of two when Trincianti JADAS10/cJADAS10 cut-offs were used compared with when Backström (11%/10%) and Consolaro (7%/3%) JADAS10/cJADAS10 cut-offs were used. CONCLUSIONS: We found the cut-offs proposed by Consolaro et al. to be the most feasible, since these cut-off levels for CID do not result in the misclassification of active disease as remission, and the proportion of patients with AJC > 1 in the LDA group is lowest using these cut-offs.

Cognitive impairment predicts poststroke death in long-term follow-up.

BACKGROUND: Poststroke global cognitive decline and dementia have been related to poor long-term survival. Whether deficits in specific cognitive domains are associated with long-term survival in patients with ischaemic stroke is not known in detail. METHODS: Patients with acute stroke subjected to comprehensive neuropsychological evaluation were included in the study (n = 409) and followed up for up to 12 years. RESULTS: In Kaplan-Meier analysis, impairments in following cognitive domains predicted poor poststroke survival (estimated years): executive functions (48.2%) (5.8 vs 10.1 years, p<0.0001), memory (59.9%) (6.8 vs 9.3 years, p = 0.009), language (28.9%) (5.3 vs 8.6 years, p = 0.004) and visuospatial/constructional abilities (55.2%) (5.6 vs 10.1 years, p<0.0001). Low Mini Mental Status Examination (MMSE)

Dynamic contrast change produces rapid gain control in visual cortex.

During normal vision, objects moving in the environment, our own body movements and our eye movements ensure that the receptive fields of visual neurons are being presented with continually changing contrasts. Thus, the visual input during normal behaviour differs from the type of stimuli traditionally used to study contrast coding, which are presented in a step-like manner with abrupt changes in contrast followed by prolonged exposure to a constant stimulus. The abrupt changes in contrast typically elicit brief periods of intense firing with low variability called onset transients. Onset transients provide the visual system with a powerful and reliable cue that the visual input has changed. In this paper we investigate visual processing in the primary visual cortex of cats in response to stimuli that change contrast dynamically. We show that 1-4 s presentations of dynamic increases and decreases in contrast can generate stronger contrast gain control than several minutes exposure to a stimulus of constant contrast. Thus, transient mechanisms of contrast coding are not only less variable than sustained responses but are also more rapid and flexible. Finally, we propose a quantitative model of contrast coding which accounts for changes in spike rate over time in response to dynamically changing image contrast.

Occupational exposure to radiofrequency fields in antenna towers.

Exposure of workers to radiofrequency fields was assessed in two medium-sized antenna towers. Towers had transmitting antennas from different networks, e.g. mobile phone networks, radio and digital TV sub-stations and amateur radio. The levels of radiofrequency fields were measured close to the ladders of the towers. All measured values were below ICNIRP occupational reference levels.

How complex interactions of ischemic brain infarcts, white matter lesions, and atrophy relate to poststroke dementia.

BACKGROUND: Cerebrovascular disease is a major factor related to cognitive impairment. However, behavioral correlates of ischemic brain lesions are insufficiently characterized. OBJECTIVE: To examine magnetic resonance imaging correlates of dementia in a large, well-defined series of patients with ischemic stroke. METHODS: Detailed medical, neurological, and neuropsychological examinations were conducted 3 months after ischemic stroke for 337 of 486 consecutive patients aged 55 to 85 years. Infarcts (type, site, side, number, and volume), extent of white matter lesions (WMLs), and degree of atrophy were categorized according to magnetic resonance images of the head. The definition for dementia of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-III) was used. RESULTS: Dementia was diagnosed in 107 (31.8%) of the patients and stroke-related dementia in 87 (25.8%). Volumes, numbers, distinct sites of infarcts, extent of WMLs, and degree of atrophy were different for the demented and nondemented subjects. Particularly, volumes of infarcts in any (right- or left-sided) superior middle cerebral artery territory (27.3 vs 13.7 cm(3), P =. 002) and left thalamocortical connection (14.8 vs 4.0 cm(3), P =. 002) differentiated the 2 groups. Logistic regression analysis showed that the correlates of any dementia included the combination of infarct features (volume of infarcts in any superior middle cerebral artery: odds ratio [OR], 1.11; frequency of left-sided infarcts: OR, 1.21), extent of WMLs (OR, 1.3), medial temporal lobe atrophy (OR, 2.1), and host factors (education; OR, 0.91). In the patients with stroke-related dementia, the main correlate was volume of infarcts in the left anterior corona radiata (OR, 1.68). CONCLUSION: Correlates of poststroke dementia do not include merely 1 feature but a combination of infarct features, extent of WMLs, medial temporal lobe atrophy, and host features.

Initial treatment of parkinsonism with 8-alpha-amino-ergoline.

We treated 12 patients with Parkinson's disease with an 8-alpha-amino-ergoline derivative, CU 32-085. The daily dosage was increased slowly to 7 mg over 9 weeks, held constant for 8 weeks, then replaced by placebo for 4 weeks. We found statistically significant benefit over placebo or pretreatment disability. The effect was seen at daily dosages of 3 mg or more. Its magnitude was dose related. There was no further improvement on prolonged treatment with 7 mg daily. Side effects were mild and did not require interruption of treatment.

Preserved stimulus deviance detection in Alzheimer's disease.

Aging attenuates automatic auditory discrimination to duration change, whereas frequency change detection is relatively unimpaired in aging and in Alzheimer's disease (AD). Here we studied with a whole-head magnetometer whether cortical auditory discrimination to duration change as shown by magnetic mismatch negativity (MMNm) response is impaired in AD. Twenty AD patients with mild to moderate cognitive impairment and 18 age-matched healthy subjects were monaurally presented a sequence of frequent standard tones embedded with occasional deviants with shorter duration. MMNm was significantly delayed in the left hemisphere ipsilaterally to the ear stimulated in the patient group, whereas the MMNm amplitudes over both hemispheres were quite similar in both groups. This suggests that although MMNm is delayed in the left hemisphere, the automatic discrimination to duration change in the auditory cortex is not attenuated in the early stages of AD.

Impaired preconscious auditory processing and cognitive functions in Alzheimer's disease.

OBJECTIVE: To study whether preconscious auditory processing is deteriorated in patients with Alzheimer's disease (AD) having mild to moderate cognitive symptoms. To investigate whether auditory processing correlates with the impairment of the higher cortical functions. METHODS: P50m and N100m responses elicited by a sequence of repetitive tones were recorded with a whole-head magnetometer from 22 patients with probable AD and from 18 healthy age-matched controls. In addition, an extensive neuropsychological test battery assessing main cognitive domains was administered to all subjects. RESULTS: The patients with AD had significantly delayed N100m responses in the left hemisphere that correlated with the impairment of the language functions. CONCLUSIONS: N100m auditory responses measured with magnetoencephalography may be useful in evaluating the severity and progression of the cortical dysfunction in dementia.

Immunohistochemical evidence for the presence of protein kinase C beta-subtype in rat motoneurons and myoneural junctions.

The localization of protein kinase C beta-subtype-like immunoreactivity (PKC-beta-LI) was studied in the spinal cord and in different striated muscles of rat. In the spinal cord, large motoneurons in the ventral horn were PKC-beta-immunoreactive (IR). Strong immunoreactivity to PKC-beta was found in large nerve bundles between muscles, and in smaller nerves among muscle fibers. Myoneural junctions, which showed weaker immunoreactivity to PKC-beta, were also demonstrated in all muscles studied; the external ocular muscles, the diaphragma and the triceps surae muscle. Muscle cells were not labelled.

Global field power of auditory N1 correlates with impaired verbal-memory performance in human alcoholics.

First weeks after alcohol withdrawal, associated with profound changes in neural transmission, constitute the critical period for relapse prevention and pharmacological intervention in alcoholism. Here, 20 male alcoholics with 1-6 weeks of abstinence and 20 age-matched healthy controls were studied using auditory event-related potentials (ERP), measured with a 32-channel electroencephalogram, and neuropsychological tests of auditory-verbal memory. Global field power maximum of ERP during 80-150 ms period after presentation of unattended tones (binaural 700 Hz pure tones, inter-stimulus interval 2.5 s) was significantly (P<0.01) larger in the alcoholics than controls. This effect, reflecting augmented N1 generation, significantly correlated (r=0.5) with impaired memory performance in the alcoholics. The profound change in pre-attentive auditory processing, predicting impaired memory performance, might reflect impaired cerebral inhibitory transmission in alcoholics.

Post-withdrawal changes in middle-latency auditory evoked potentials in abstinent human alcoholics.

We investigated the effects of chronic alcoholism on middle-latency auditory evoked potentials (MAEP) in 14 male alcoholics with 1-6 weeks of abstinence (without other severe disorders) and 13 age-matched male social-drinker controls. The peak amplitude of a positive deflection (Pa) of the MAEP, peaking at about 30 ms post-stimulus, was significantly larger in the alcoholics than in the controls (P < 0.01), and notably, a significant negative correlation (r = -0.65) was observed between the Pa amplitude and duration of abstinence in the alcoholics. The present results suggest that the post-withdrawal brain hyperexcitability in the alcoholic brain, gradually recovering with abstinence, could be objectively and non-invasively studied with the MAEP.

MRI correlates of dementia after first clinical ischemic stroke.

BACKGROUND AND PURPOSE: Dementia after first clinical stroke frequently has been found, but the clinical and radiological correlates have not been fully detailed. We examined magnetic resonance imaging (MRI) correlates of dementia in a large well-defined series of patients with first clinical ischemic stroke. METHODS: Detailed medical, neurological and neuropsychological examination was conducted 3 months after ischemic stroke for 273 patients with first clinical stroke from a consecutive series of 486 patients aged 55-85 years. MRI of the head categorised infarcts (type, site, side, number, volume), extent of white matter lesions (WMLs) and degree of atrophy. The DSM-III definition for dementia was used. RESULTS: Dementia was diagnosed in 79 (28.9%) of the patients with first clinical stroke. Volumes, numbers, distinct sites of infarcts, extent of WMLs and degree of atrophy were different for the demented and nondemented subjects. Logistic regression analysis showed that the correlates of dementia included the combination of infarct features (volume of infarcts in left-sided anterior corona radiata; OR 1.86), extent of WMLs (OR 1. 37), medial temporal lobe atrophy (OR 3.4) and host factors (low education; OR 1.11). The additive effect of having more than one correlate was detected (OR 2.53). CONCLUSIONS: Dementia occurring after first clinical stroke is frequent and not solely due to a single stroke, but contain a combination of infarcts features, extent of WMLs, medial temporal lobe atrophy and host factors reflecting more than one underlying pathology.

Dementia in movement disorders.

Of all the movement disorders, Huntington's disease has been most consistently associated with dementia, while it is only over the last decade that intellectual cognitive decline have been recognized as common features of Parkinson's disease. It is now known that the pathology in these two conditions reflects differential involvement of the striatum. The Huntington lesion is primarily in the caudate, while the Parkinson lesion preferentially affects the putamen. Both conditions have more diffuse pathology, and dementia may also occur in a wide range of other extrapyramidal diseases, such as progressive supranuclear palsy, the parkinsonism-dementia complex of Guam, and certain spinocerebellar degenerations. Clinicopathological correlations will be reviewed in these disorders of primarily subcortical pathology, and comparisons will be made with Alzheimer's disease, a disorder of predominantly cortical pathology.

The age of onset of Parkinson's disease: etiological implications.

We have conducted a hospital-based survey of the age-specific prevalence of Parkinson's disease in 551 patients from Helsinki and Vancouver. We conclude that the disorder may be starting earlier than previously and we discuss the implications of this finding for the etiology of Parkinson's disease.

Magnetic fields of video display terminals and pregnancy outcome.

The magnetic fields emitted by video display terminals (VDTs) and their potential association with pregnancy outcome are discussed. The majority of the epidemiologic studies suggest that VDT work is not related to adverse pregnancy outcome. The exposure to magnetic fields from modern VDTs is usually even lower than that from other sources in the office environment, such as printers and photocopying machines. There are, however, some indications of an increased risk of adverse pregnancy outcome among women exposed to high levels of extremely low-frequency magnetic fields of VDTs or electric appliances at home. Because the present evidence is not sufficient to allow the drawing of final conclusions, it would be important to examine the effects of exposure to higher fields existing at industrial work places.

Ocular exposure to solar ultraviolet and visible radiation at high latitudes.

Exposure of the eyes to ultraviolet (UV) radiation and short wavelength light, blue light, from the sun was assessed under realistic geometric conditions. A spectroradiometer with a double monochromator was used to determine the spectral irradiance at 1-nm intervals within the wavelength range of 250-800 nm. Biological weighting functions were used to calculate the blue-light radiance and the weighted UV irradiance. In addition, a photometer with a 1 degree angle of view was used to measure the ambient luminance. The results indicate that sizable amounts of UV radiation and blue light can be reflected from different environmental surroundings. Hence various groups of outdoor workers seem to be at risk of chronic ocular overexposure to solar radiation. When occupational exposure limits for UV and visible radiation are revised, the risks of chronic exposure should receive more consideration than to date.

Human brain activity during exposure to radiofrequency fields emitted by cellular phones.

OBJECTIVES: The aim of this study was to explore the possible influence of radiofrequency (RF) radiation exposure on human brain function. METHODS: The electroencephalographic (EEG) activity of 19 volunteers was quantitatively analyzed. Ten of the subjects were men (28-48 years of age) and 9 were women (32-57 years of age). The sources of exposure were 5 different cellular phones (analogue and digital models) operating at a frequency of 900 MHz or 1800 MHz. The EEG activity was recorded in an awake, closed-eyes situation. Six 30-minute experiments, including 1 sham exposure, were made for each subject. The duration of a real exposure phase was 20 minutes. RESULTS: Exposure to one of the phones caused a statistically significant change in the absolute power at the delta band of the EEG recording. However, no difference was seen in the relative power of the same band, and no changes occurred during exposure to other phones at any frequency bands. CONCLUSIONS: The findings of this study suggest that exposure to radiofrequency fields emitted by cellular phones has no abnormal effects on human EEG activity. The observed difference in 1 parameter was probably caused by statistical chance.