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Biomedical subjects

M Hietanen

Publications and source records attributed to M Hietanen.

At least 19 recordsLinked to original sources
PubMed2002

Post-stroke depression, executive dysfunction and functional outcome.

The early diagnosis of vascular cognitive impairment has been challenged and executive control function has been suggested to be a rational basis for the diagnosis of vascular dementia. We sought to examine the correlates of executive dysfunction in a well-defined stroke cohort. A group of 256 patients from a consecutive cohort of 486 patients with ischaemic stroke, aged 55-85 years, was subjected to a comprehensive neuropsychological examination 3-4 months after ischaemic stroke and 188 of them in addition to detailed psychiatric examination. Basic and complex activities of daily living (ADLs) (bADLs and cADLs) post-stroke were assessed. The DSM-III-R criteria were used for the diagnosis of the depressive disorders. Altogether 40.6% (n=104) of the patients had executive dysfunction. The patients with executive dysfunction were older, had lower level of education, were more often dependent, did worse in bADLs and cADLs, had more often DSM-III dementia, had worse cognition as measured by Mini Mental State Examination (MMSE) and were more depressed as measured by the BECK depression scale, but not with the more detailed psychiatric evaluation. They had more often stroke in the anterior circulation and less often in the posterior circulation. The independent correlates of executive dysfunction were cADLs (OR 1.1, 95% CI 1.03-1.16), each point of worsening in cognition by MMSE (OR 1.7, 95% CI 1.42-1.97) and stroke in the posterior circulation area (OR 0.4, 95% CI 0.18-0.84). Clinically significant executive dysfunction is frequent after ischaemic stroke and is closely connected with cADLs and to overall cognitive status but could be distinguished from depression by detailed neuropsychological examination. Executive measures may detect patients at risk of dementia and disability post-stroke.

Activities of Daily Living↗
PubMed2001

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.

Acoustic Stimulation↗
PubMed2000

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.

Aged↗
PubMed2000

The inheritance of neuropsychological dysfunction in twins discordant for schizophrenia.

While genetic influences in schizophrenia are substantial, the disorder's molecular genetic basis remains elusive. Progress has been hindered by lack of means to detect nonpenetrant carriers of the predisposing genes and by uncertainties concerning the extent of locus heterogeneity. One approach to solving this complexity is to examine the inheritance of pathophysiological processes mediating between genotype and disease phenotype. Here we evaluate whether deficits in neurocognitive functioning covary with degree of genetic relationship with a proband in the unaffected MZ and DZ co-twins of patients with schizophrenia. Twin pairs discordant for schizophrenia were recruited from a total population cohort and were compared with a demographically balanced sample of control twin pairs, on a comprehensive neuropsychological test battery. The following four neuropsychological functions contributed uniquely to the discrimination of degree of genetic loading for schizophrenia and, when combined, were more highly correlated within MZ pairs than within DZ pairs, in both discordant and control twins: spatial working memory (i.e., remembering a sequence of spatial locations over a brief delay), divided attention (i.e., simultaneous performance of a counting and visual-search task), intrusions during recall of a word list (i.e., "remembering" nonlist items), and choice reaction time to visual targets. Together with evidence from human and animal studies of mediation of these functions by partially distinct brain systems, our findings suggest that there are multiple independently inherited dimensions of neural deficit in schizophrenia and encourage a search for genes contributing to quantitative variation in discrete aspects of disease liability. On tests of verbal and visual episodic memory, but not on the liability-related measures, patients were more impaired than their own MZ co-twins, suggesting a preferential impact of nongenetic influences on long-term memory systems.

Adult↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Aged↗
PubMed2000

Safe use of mobile phones in hospitals.

This research evaluated possibilities to use different types of mobile telephones in the hospital environment by testing the disturbances in medical equipment caused by radiofrequency fields emitted by the phones. The research was carried out by the Finnish Institute of Occupational Health (FIOH) in cooperation with the Technical Research Centre of Finland (VTT), and focused mainly on equipment situated within the Maria Hospital of the City of Helsinki. The Helsinki Hospital District and tile Medical Engineering Centre of the Helsinki University Central Hospital (HUCH) also participated in this project.

Equipment and Supplies, Hospital↗
PubMed2000

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.

Adult↗
PubMed2000

Increased distractibility by task-irrelevant sound changes in abstinent alcoholics.

BACKGROUND: Chronic alcoholism is accompanied by "frontal" neuropsychological deficits that include an inability to maintain focus of attention. This might be associated with pronounced involuntary attention shifting to task-irrelevant stimulus changes and, thereafter, an impaired reorienting to the relevant task. The neural abnormalities that underlie such deficits in alcoholics were explored with event-related potential (ERP) components that disclosed different phases of detection and orienting to stimulus changes. METHODS: Twenty consecutive abstinent male alcoholics (DSM-IV) and 20 age-matched male controls (healthy social drinkers) were instructed to discriminate equiprobable 100 and 200 msec tones in a reaction-time task (RT) and to ignore occasional, either slight (7%) or wide (70%), frequency changes (hypothesized to increase RT) during an ERP measurement. RESULTS: In the alcoholics, we found pronounced distractibility, evidenced by a RT lag (p < 0.01) caused by deviants, that correlated (Spearman p = 0.5) with a significantly enhanced (p < 0.01) amplitude of mismatch negativity (MMN) to deviants. Significantly increased RT lag for trials subsequent to deviants (slight p < 0.001, wide p < 0.05) in the alcoholics suggested impaired reorienting to the relevant task. The MMN enhancement also predicted poorer hit rates in the alcoholics (Spearman p = 0.6-0.7). Both the MMN enhancement and pronounced distractibility correlated (Spearman p = 0.4) with an early onset of alcoholism. CONCLUSIONS: Attentional deficits in the abstinent alcoholics were indicated by the increased distractibility by irrelevant sound changes. The MMN enhancement suggested that this reflects impaired neural inhibition of involuntary attention shifting, being most pronounced in early-onset alcoholics.

Adult↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Aged↗
PubMed1999

Executive functions and speed of mental processing in elderly patients with frontal or nonfrontal ischemic stroke.

Impairments in executive functions have been related to aging and frontal lobe lesions. Aging also causes slowing of mental processing. We examined whether ischemic stroke in the frontal brain area results in dysexecutive syndrome, or whether the frontal stroke causes increased slowing of mental processing. Neurological, radiological and neuropsychological examinations were carried out 3 months post-stroke on 250 ischemic stroke patients (55-85 years) and on 39 healthy control subjects. Of the patients, 62 had frontal and 188 had nonfrontal lesions. The neuropsychological examination comprised several cognitive domains, including tests considered to measure executive functions. The frontal group was slower than the nonfrontal group in tasks measuring speed of mental processing which were time-limited (Trail Making A, Stroop dots and fluency). They were also inferior in the Digit Span backwards task. There were no differences between the groups in other cognitive domains, nor in some tests which are considered to be measures of executive functions (e.g. WCST). Impairments in executive functions were evident in both the frontal and the nonfrontal groups compared with the controls, but no dysexecutive syndrome specifically related to frontal lesions was found. Frontal stroke related mainly to the slowing of mental processing.

Age Factors↗
PubMed1999

Modified activation of somatosensory cortical network in patients with right-hemisphere stroke.

To study the effects of parietal lesions on activation of the human somatosensory cortical network, we measured somatosensory evoked fields to electric median nerve stimuli, using a whole-scalp 122-channel neuromagnetometer, from six patients with cortical right-hemisphere stroke and from seven healthy control subjects. In the control subjects, unilateral stimuli elicited responses which were satisfactorily accounted for by modelled sources in the contralateral primary (SI) and bilateral secondary (SII) somatosensory cortices. In all patients, stimulation of the right median nerve also activated the SI and SII cortices of the healthy left hemisphere. However, the activation pattern was altered, suggesting diminished interhemispheric inhibition via callosal connections after right-sided stroke. Responses to left median nerve stimuli showed large interindividual variability due to the different extents of the lesions. The strength of the 20-ms response, originating in the SI cortex, roughly reflected the severity of the tactile impairment. Right SII responses were absent in patients with abnormal right SI responses, whereas the left SII was active in all patients, regardless of the responsiveness of the right SI and/or SII. Our results suggest that the human SI and SII cortices may be sequentially activated within one hemisphere, whereas SII ipsilateral to the stimulation may receive direct input from the periphery, at least when normal input from SI is interrupted.

Adult↗
PubMed1999

Suppression of mismatch negativity by backward masking predicts impaired working-memory performance in alcoholics.

BACKGROUND: Pronounced disruption of memory traces by subsequent distractors may result in impaired behavioral memory performance in alcoholics. METHODS: This hypothesis was investigated with an electrophysiological index of auditory sensory-memory traces, mismatch negativity, a preattentive event-related potential component elicited by a "deviant" tone within a train of "standard" tones. RESULTS: Inserting a masking stimulus after these tones abolished mismatch negativity in alcoholics (DSM-IV) but not in social-drinker controls. This effect predicted working-memory impairment in alcoholics, and correlated significantly with self-reported alcohol consumption of the subjects. Furthermore, the backward-masking mismatch negativity paradigm detected sensory-memory impairment in 9 of 20 alcoholics (sensitivity 45%), whereas all 20 social drinkers were unimpaired (specificity 100%). CONCLUSIONS: Vulnerability to memory trace disruption by shortly following sounds may be one of the factors contributing to behavioral memory dysfunction in alcoholics. The present result may provide an objective neurophysiological tool for investigation of alcohol-induced and other degenerative brain disorders.

Adult↗
PubMed1998

Clinical determinants of poststroke dementia.

BACKGROUND AND PURPOSE: Frequency of poststroke dementia is high, and stroke considerably increases the risk of dementia. The risk factors for dementia related to stroke are still incompletely understood. We sought to examine clinical determinants of poststroke dementia in a large well-defined stroke cohort. METHODS: The study group comprised 337 of 486 consecutive patients aged 55 to 85 years who 3 months after ischemic stroke completed a comprehensive neuropsychological test battery and MRI, including structured medical, neurological, and laboratory evaluations; clinical mental status examination; interview of a knowledgeable informant; detailed history of risk factors; and evaluation of stroke type, localization, and syndrome. The DSM-III definition for dementia was used. RESULTS: Frequency of any poststroke dementia was 31.8% (107/337), that of stroke-related dementia (mixed Alzheimer's disease plus vascular dementia excluded) was 28.4% (87/306), and that of dementia after first-ever stroke was 28.9% (79/273). The patients with poststroke dementia were older and more often had a low level of education, history of prior cerebrovascular disease and stroke, left hemispheric stroke (reflecting laterality), major dominant stroke syndrome (reflecting laterality and size), dysphasia, gait impairment, and urinary incontinence. The demented patients were also more frequently current smokers, had lower arterial blood pressure values, and more frequently had an orthostatic reaction compared with the nondemented stroke patients. The correlates of dementia in logistic regression analysis were dysphasia (odds ratio [OR], 5.6), major dominant stroke syndrome (OR, 5.0), history of prior cerebrovascular disease (OR, 2.0), and low educational level (OR, 1.1). When we excluded those with cerebrovascular disease plus Alzheimer's disease or those with recurrent stroke, the order of correlates remained the same. When the patients with dysphasia (n=30) were excluded, the correlates were major dominant syndrome (OR, 4.6) and low educational level (OR, 1.1). CONCLUSIONS: Our data suggest that a single explanation for poststroke dementia is not adequate; rather, multiple factors including stroke features (dysphasia, major dominant stroke syndrome), host characteristics (educational level), and prior cerebrovascular disease each independently contribute to the risk.

Age Factors↗
PubMed1995

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.

Computer Terminals↗
PubMed1994

Psychomotor capacity and occurrence of wrist tenosynovitis.

A case-referent study was carried out among meatcutters, sausage markers, and packers in a large meat-processing plant to investigate the association between psychomotor capacity and occurrence of tenosynovitis. Reaction time, movement time, manual dexterity, visual attention and visuospatial ability were measured in 26 cases with a history of two or more episodes of tenosynovitis and 26 referents of similar gender, occupation, age, and job seniority with no episodes of the disease. No differences were found between the cases and the referents in any of the tests of psychomotor capacity. The results suggest that psychomotor capacity, as measured with the tests of this study, is a poor predictor of wrist tenosynovitis.

Adult↗