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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to address basic mechanisms behind a reduced averaged P300 wave in schizophrenia and depression, 17 unmedicated schizophrenic and 11 unmedicated depressive subjects were tested in an 'oddball paradigm' against healthy controls matched for gender and age. The amplitude distributions of single trials' maximum positive deflections after stimulation (P300) for both target and nontarget stimuli were determined, which served as a basis for calculating the discrimination index d'. This index characterizes differences in the electrophysiological responses to target and nontarget stimuli of a subject being engaged in a discrimination task. As a main result d' was significantly lower for schizophrenics than for their controls. Directly compared to depressive subjects, schizophrenics also depicted a statistically significant decrease of the discrimination index, which could not be explained by differences in age. Although the averaged P300 signals did not show any significant differences between the two diagnostic groups, the approach of calculating d' on the basis of single trial analysis differentiated between schizophrenics and depressives. In conclusion, schizophrenic patients revealed different functional features when generating event-related potentials in an 'oddball paradigm' compared to healthy controls and depressives.
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PMID:Differential pathophysiological mechanisms of reduced P300 amplitude in schizophrenia and depression: a single trial analysis. 926 77

We examined event-related potentials in patients with senile depression and silent cerebral infarction (SCI) to clarify the features of the P300 component. P300 event-related potentials were recorded in drug-free depressed patients (N = 16) and normal controls (N = 17). All patients underwent magnetic resonance imaging and were classified as SCI-positive (N = 7) or SCI-negative (N = 9). In depressed patients, the P300 was reexamined after antidepressant treatment. Prior to treatment, P300 amplitudes in depressed patients were significantly smaller than those in normal controls (P < 0.01). P300 amplitudes increased significantly in SCI-negative patients following recovery (P < 0.05), but did not change in SCI-positive patients. SCI may interrupt the treatment-related P300 amplitude increase in depressed patients.
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PMID:Changes in auditory P300 in patients with major depression and silent cerebral infarction. 954 23

Event related Potentials, which seem to be an objective parameter reflecting cognitive functions, have been examined in depression. To evaluate the influence of visual and auditory stimuli on the P300 latency we studied 42 patients with major depression and 21 normal subjects. The experimental tasks applied were first a series of 300 auditory stimuli [255 (85%) were tones of 1000 Hz, and considered the frequent stimulus, whereas 45 (15%) were tones of 2000 Hz and referred to as the rare stimulus and second a series of 300 visual stimuli 255 (85%) were black circles on a white background, and considered the frequent stimulus, 9 cm diameter, 200 ms duration whereas 45 (15%) were back squares on a white background and referred to as the rare stimulus, 9 cm diameter, 200 ms duration] in the center of a computer screen. The results shown an increase of P300 latency in depressive patients during auditory and visual tasks. Non differences were found in reaction time to visual or auditory stimuli. These results are consistent with an impairment in brain function in depressive patients that is associated with cortical hypoactivity and deficits in perceptive, auditory or visual, functions.
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PMID:[Cortical processing of visual and auditory stimuli in depressive patients: a study with event related potentials]. 980 54

Although anxiety and stress were two distinguished concepts, they were used confusedly by medical and psychological talks. Whereas anxiety is currently a well-known psychopathological notion, stress remains blurred and unclear. The aim of the study was of course to exhibit the relationships between stress and anxiety, but also to show by which mechanisms anxiety would have a role in the stress-response modulation. Three groups of subjects, paired in age and sex, were compared: 28 paid controls (13 male) aged 37 +/- 12 years, 25 subjects (12 male) aged 38 +/- 8 who consulted in a framework of CITES Prevert (clinic of stress) but without mental disorders, and 28 subjects (13 male) aged 37 +/- 12, out-patients suffering from anxiety disorders (generalized anxiety disorders according to DSM IV). All of subjects were drug free when examined. They were submitted to auto-evaluation psychological tests: Amiel-Lebigre life events, Spielberger anxiety trait and state, Plutchik and Van Praag depression and finally Chapman anhedonia. After that, two ERPs were recorded, the P300 by using the classical "Oddball experimental paradigm" in auditive modality and the Contingent Negative Variation (CNV) by using a reaction time task with warning stimulus. A close relationships between stress and anxiety could be an evidence as showed by the positive correlations between life events and psychological data (anxiety and depression). In addition, the results displayed correlations between anxiety trait and CNV reaction time (positive correlation) and early P300 (P3a) component amplitude (negative correlation). This could support the hypothesis according to the anxiety would disturb the behavior (slow motor response) and the cognitive processes (attentional changes), and therefore would have a role in the stress-response modulation. Nevertheless, anxiety trait were not correlated to the late P300 component (P3b) amplitude, thus to controlled attention processes. Moreover P3b amplitude were reduced exclusively in subjects who suffered from anxiety disorders. This could mean that anxiety trait would not be solely involved in cognitive changes. Pathological states, as anxiety disorders, could involve another logic of the mental functioning. These results will be discussed according to the cognitive psychology and psychophysiology knowledges.
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PMID:[Stress and anxiety: what are they?]. 994 39

Many clinical neurophysiology laboratories have added average evoked potential studies to their routine procedures as evoked potential recording methods are non invasive, highly objective and informative. Indeed, short latency brainstem auditory evoked potentials as well as short and intermediate latency cortical evoked potentials, lately have proved to be valuable clinical tools for objectively testing afferent functions in patients with neurological and sensory disorders. The averaged evoked potential responses (EPR) have been widely used in clinical practice to record the changes in the electrical potentials that occur within the central nervous system (CNS) of the patient in response to an external stimulus. Two types of evoked potentials are usually recorded. 1-Stimulus related, short latency evoked potentials, which represent an obligate neuronal response to a given stimulus and both the amplitudes and latencies of these depend on the physical characteristics of the eliciting stimulus. In this category brainstem auditory evoked potentials (BAEPs), visual evoked potentials (VEPs) and somatosensory evoked potentials (SEPs), have normal values for latencies, amplitudes of waves and characteristic wave form. Any abnormality of these reflects excitation, conduction block in the specific pathways in the CNS. Certain abnormalities in EPR reflect subclinical involvement of CNS even before the disease clinically manifests. Abnormality in BAEPs can in addition, depict the exact site of lesion in the brainstem auditory pathways. Same is true for SEPs where abnormalities in far-field or near-field components, reflect lesions at the plexus, spinal cord, brainstem or thalamo-cortical regions respectively. 2- The event related potentials (ERPs) can be recorded in response to an external stimulus to which person is attentive or an event requiring cognition, discrimination, or reaction to the target stimulus. P300 is one such ERP, helpful in distinguishing between disorders such as dementia and depression. This first review gives a bird's eyeview of the essentials, methods, interpretation and clinical applications of stimulus evoked short latency (brainstem auditory, visual and somatosensory) responses in human beings.
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PMID:Average evoked potentials--clinical applications of short latency responses. 1022 45

The identification of the brain structures and neurotransmitters responsible for the generation and/or modulation of P300 could lead to important clinical implications. Since serotonin disturbances seem to play a critical role in depression, the aim of the study was to assess the possible relationships between the P300 event-related brain potential and serotonergic activity in depression. The study was conducted among 45 major depressive inpatients, and serotonergic activity was assessed by prolactin (PRL) response to flesinoxan (a 5-HT1A agonist). Results showed a significant negative correlation between P300 amplitude and PRL response to flesinoxan (r = -0.40, P = 0.007 at Cz; r = -0.47, P = 0.001 at Pz). In contrast, both P300 latency and reaction time were not related to endocrine response. This study supports a role for serotonin-1A in the neurobiological modulation of P300 amplitude.
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PMID:P300 event-related potential and serotonin-1A activity in depression. 1057 39

The authors asked whether impaired executive functioning and long P300 latency are related dysfunctions and whether they are associated with geriatric depression. A group of 25 elderly depressed patients without dementia and 20 control subjects were assessed on tasks of fluency, initiation and perseveration, the Stroop task, the Wisconsin Card Sorting Test (WCST) perseverative error score, and P300 latency. The groups' performance differed significantly on these tasks and in P300 latency. Longer latency was associated with poorer performance in both groups on all measures except WCST perseverative errors. Regardless of patients' depression status, increased P300 latency predicts poorer performance on executive function tasks requiring speeded performance.
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PMID:Executive functions and P300 latency in elderly depressed patients and control subjects. 1064 96

Endogenous evoked potentials of two types (CNV and P300 complexes) as well as their respective reaction times were recorded in 29 elderly, active subjects (15 men and 14 women) between 60 and 84 years of age. Our subjects also passed anxiety, depression and cognitive scales. The different results were then analyzed in relation with each other and in relation with age and sex. No age-related differences were found in the principal elements measured in the P300 complex, but several elements of the CNV complex were clearly shown to be age-sensitive. Sex-related differences were found in the N2 and P3a potentials. CNV morphology (Tecce type A) and cognitive scores were found to be related to Spielberger's anxiety-trait sub-scale. Several results also highlighted the heterogeneity of this age group. The need for complementary studies in this age group is then discussed with the hope that neurophysiology can become a useful tool in psychogeriatrics.
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PMID:[A study of endogenous evoked potentials (P300 and CNV) in retired patients]. 1066 95

Many studies involving various electrophysiological parameters have been conducted in psychiatric disorders like schizophrenia and dementia to assess their cognitive dysfunctions. Not much reports are available in major depression. The present study was conducted in 20 patients of major depression to evaluate their cognitive functions in terms of P300. P300 or P3 wave of auditory event related evoked potentials (ERPs) is usually seen around 300 msec of presenting of target stimulus, if the subject is responding to it. Auditory ERPs were recorded using the standard 'odd ball' paradigm. The latencies of various components of ERPs N1, N2, P1, P2, and P3 were recorded and compared with those of 20 normal age and sex matched controls. The latency of P300 was found to be significantly delayed in cases of major depression as compared to that of controls. Other waves were also delayed in cases of depression but the difference was not statistically significant. Our results suggest that P300 latency is longer in the patients of major depression disorders which could be due to constitutive altered 'cognitive neuronal pool' or a neurotransmitter/neuropeptide imbalance. Further studies involving larger populations are required to elucidate the diagnostic and predictive role of latency of P300 in the cases of depression.
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PMID:A study of P300-event related evoked potential in the patients of major depression. 1077 86

P300 is an event-related brain potential (ERP) particularly interesting to the study of cognitive processes in normal subjects and in psychopathology. P300 has been applied in depression with controversial results. A major source for these controversial results could result from the diversity of depressed patients included in the different studies. Supporting this assumption, impulsivity, blunted affect, suicidal behavior and psychotic features significantly influence P300 amplitude. However, no data are available on the possible influences of the personality of depressed patients on P300. Since personality is related to P300 in normal subjects, the aim of the present study is to investigate the relationship between ERPs (P200, N200, and P300) and the Temperament and Character Inventory (TCI) in 54 depressed patients. The main results of the study concern the absence of major correlations between personality dimensions as assessed by the TCI and ERP parameters among depressed patients. Only weak partial positive correlations relate N200 latency with harm avoidance, and P300 amplitude (Pz) with the self-directedness dimension. N200 amplitude is also negatively correlated to persistence. However, the preliminary nature of the presented results with respect to the weak statistical significance should be underlined.
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PMID:P300 event-related brain potential and personality in depression. 1100 32


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