Magnetic resonance imaging measurement of the caudate nucleus in adolescents with attention-deficit hyperactivity disorder and its relationship with neuropsychological and behavioral measures.

OBJECTIVE: To investigate structural basal ganglia abnormalities in attention-deficit hyperactivity disorder (ADHD) and their relationship with the neuropsychological deficits and behavioral problems found in ADHD. DESIGN: Case-control study. SETTING: Adolescents were recruited from a local polytechnic institute of secondary education. SUBJECTS: Eleven adolescents with ADHD and 19 healthy control subjects. Subjects with ADHD were diagnosed by the school psychologist from a total population of 450 students according to the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Diagnosis was confirmed by the Conners Teachers Rating Scale and a structured family interview. MAIN OUTCOME MEASURES: Magnetic resonance imaging single-slice transversal measurements of the head of the caudate nucleus and a comprehensive neuropsychological evaluation, which was specially designed to assess frontal-striatal functioning. RESULTS: The ADHD group had a larger right caudate nucleus area than the control group. In control adolescents, larger caudate nucleus areas were associated with poorer performance on tests of attention and higher ratings on the Conners Teachers Rating Scale. CONCLUSIONS: These findings provide further evidence of the involvement of the caudate nucleus in the neuropsychological deficits and behavioral problems found in ADHD. The larger caudate nucleus found in the ADHD group could be related to a failure of the maturational processes that normally result in volume reduction.

Effects of repetitive transcranial magnetic stimulation on memory subtypes: a controlled study.

Repetitive transcranial magnetic stimulation (rTMS) of human cortex may disrupt or facilitate cortical activity. The aim of the present study was to investigate the consequences of rTMS applied over different cortical areas during various memory tasks, measuring immediate, working and episodic verbal memory. The study was performed in 16 right-handed healthy men. A double-blind, cross-over, within-subject repeated measures design was used. There were five rTMS conditions: baseline without stimulation, high frequency (HF) rTMS over right and left dorsolateral prefrontal cortex (DLPFC) and over right cerebellum, and low frequency (LF) parameters over left DLPFC. Digits forwards and backwards and letter-number sequencing of the Wechsler Adults Intelligence Scale (WAIS) were used to assess immediate and working verbal memory, and logical memory of the Rivermead Behavioural Memory Test was used to assess episodic memory encoding. An analysis of variance (ANOVA) for repeated measures in the scores of each memory task according to rTMS conditions was used. Significantly lower scores in the number of memory units of the episodic memory task were observed when rTMS high frequency parameters were applied over left DLPFC (P=0.009). No significant differences were found in the other memory subtype tasks analysed during the different rTMS conditions. These findings provide evidence for the significant role of the left DLPFC in episodic verbal memory processes.

Right hemisphere dysfunction in subjects with attention-deficit disorder with and without hyperactivity.

The attention-deficit disorder, with and without hyperactivity, is associated with defective attention, response inhibition and, in attention-deficit disorder with hyperactivity, with motor restlessness. In adults, inattention, defective response inhibition, and impersistence are more commonly seen in right hemisphere lesions. In the present study, we investigate possible right hemisphere dysfunctions in attention-deficit disorder with hyperactivity and attention-deficit disorder without hyperactivity. The right hemisphere performance of 60 teenagers, 16 having attention-deficit disorder with hyperactivity, 9 having attention-deficit disorder without hyperactivity, and 35 controls, selected clinically (DSM-III) and experimentally (through Continuous Performance Test and Paced Auditory Addition Task), with normal IQ was assessed using a wide-ranging battery of visuospatial, visuoperceptive, and visuoconstructive functions (Benton's Line Orientation, Benton's Visual Retention, Raven's Progressive Matrices, Wechsler Adult Intelligence Scale [WAIS] Block-Design, Rey's Complex Figure). Teenagers with attention-deficit disorder with and without hyperactivity performed significantly worse than controls. Greater differences were found between subjects with attention-deficit disorder without hyperactivity and control than between subjects with attention-deficit disorder with hyperactivity and control subjects. Our results seem to be consistent with right-hemisphere dysfunction, especially in subjects with attention-deficit disorder without hyperactivity. Additionally, WAIS Block-Design and Benton's Line Orientation are the visuospatial tests with the highest discriminant power to differentiate between controls, subjects with attention-deficit disorder without hyperactivity, and subjects with attention-deficit disorder with hyperactivity.

[Dyslexia: actual status of our neurological and neuropsychological knowledge]. / La dislexia. Estado actual de neuestros conocimientos neurológicos y neuropsicológicos.

Developmental dyslexia is a neurological syndrome of unknown origin. Historical, conceptual, etiological, epidemiological aspects of developmental dyslexia are reviewed in a neuropsychological perspective. This article also reviews the known neuroanatomic, neuropathologic, and diagnostic basis of developmental dyslexia. Dislexic typology, with specific deficits in language, the visual domain or both, is discussed. Developmental dyslexia may be associated with several neuropsychological deficits. Its screening must be cognitively complete and according to accepted diagnostic criteria; a disorder manifested by difficulty in learning to read despite conventional instruction, adequate intelligence, and sociocultural opportunity.

[Neuropsychology of left-handedness: current knowledge]. / Neuropsicología de la zurdería: conocimientos actuales.

About 10% of the population is left-handed or non-right handed. Its brain organization and cognitive skills could differ in relation to right-handed subjects. Our current knowledge is far of get to know its etiology. The scientific literature is sufficiently wide as interesting to review its main contributions. The experimental studies undertake the last 30 years, but this current revision is centred on studies from the last 10 years. From them it is concluded that in Neuropsychology of the left-handedness there are great disagreements. The investigation needs to distinguish types of left-handedness or non-right-handedness, while it is not demonstrated that there is a single type of left-handedness.

[Attention: a complex cerebral function]. / La atención: una compleja función cerebral.

INTRODUCTION: Attention is a brain neurocognitive state of preparing what precedes perception and action, and is a result of cortical and subcortical networks. Attention selectively focuses our consciousness while filtering the constant flow of sensory information, selects competent parallel processing among stimuli and activates brain zones for ordering appropriate responses. DEVELOPMENT: From a neurofunctional point of view this paper reviews and describes attention as a brain function regulated by three interrelated systems: Alertness or arousal providing tonic attention, dependent on the mesencephalic reticular activating system and its connections: posterior attention or attention of perceptive selectivity that depends on zones of the right posterior parietal cortex and its connections; and, anterior attention or supervisory attention that regulates deliberate attention, and supported by zones of the anterior cingulate and lateral prefrontal cortex and the connections of the zones.

[Frontal lobes: the executive brain]. / Los lóbulos frontales: el cerebro ejecutivo.

OBJECTIVE: To describe the current basic functional neuroanatomy of the frontal lobes and complex cognitive processes associated with this wide brain zone. DEVELOPMENT: We reviewed recent studies with neurofunctional interest. We structured the frontal zones and the cognitive functions more specifically humans, named 'executive functions'. We classified the frontal syndrome into more specific syndromes; and, we reviewed the fronto-cortical and subcortical connections, which are the basis of the frontal zones and functions. CONCLUSIONS: The frontal lobe is not a single anatomical and functional brain region. Regions and fronto-cortical and subcortical circuits within the frontal lobe are associated with motor functions and cognitive processes highly specialized, which may be differently affected.

[Progressive aphasia without dementia]. / Afasia progresiva sin demencia.

INTRODUCTION: Slowly progressive aphasia without generalized dementia is considered as a degenerative disorder that can be differentiated of others well-known neurodegenerative disorders. CLINICAL CASE: We present a case report of a patient with slowly progressive aphasia, characterized by a progressive anomia and without generalized dementia. The patient was evaluated in the last four years: a neuropsychological assessment, a neurological exploration and structural (MRI) and functional (SPECT) neuroimaging were performed. CONCLUSION: This case is interesting on account of a selective implication of the left temporal hemisphere is showed in the pathogenesis of this disorder.

[Memory and learning: 'experience' and 'skill' of the brain]. / La memoria y el aprendizaje: 'experiencia' y 'habilidad' en el cerebro.

OBJECTIVE: To describe the current typology and different processes involved in memory and learning, as well as adequate tests in the diagnosis of the mnesic disorders. DEVELOPMENT: We reviewed the most recent studies about functional and lesional neuroanatomy of memory and learning and their neurophysiological bases (cellular and biochemical), with special emphasis in studies published in the three last years. We structured a typological classification, we expose the processes involved in short-term and long-term memory, we detailed the mnesic processes of declarative and implicit type, and we expose profiles of amnesias frequent in the clinical neurology and neuropsychology. CONCLUSIONS: Memory is not a diffuse and unitary process in our brain, neither amnesia is an absolute loss of memory. The multidimensional combination of two temporary memories (short- and long-term) and three mnesic processes ('working memory', explicit and implicit memory-learning) increases our capacity to memorize and learn, and it allows us to store the information in distinctive periods, with different mechanisms and covering different necessities. Patients with amnesia exhibit distinctive profiles of mnesic processes affected.

[Attention deficit hyperactivity disorder. Cerebral asymmetry observed on magnetic resonance]. / Trastorno por déficit de atención con hiperactividad. Asimetrías cerebrales observadas en resonancia magnética.

INTRODUCTION: Anatomical and functional neuroimaging data from subjects with Attention Deficit Hyperactivity Disorder (ADHD) have consistently implicated a reversal of cerebral asymmetry and suggested a fronto-striatal dysfunction in this disorder. OBJECTIVE: The aim of this study is to investigate the brain asymmetries in a homogeneous and non-medicated sample of adolescents with ADHD who had been previously studied in our laboratory. PATIENTS AND METHODS: T1-weighted magnetic resonance images were obtained for 11 adolescents with ADHD and 19 control subjects. Frontal and posterior brain regions, caudate nucleus, and ventricular system were quantitatively measured. RESULTS: A reversed pattern of asymmetry for the caudate nucleus (right > left) was found in ADHD when compared to the control group. We also found a reversed pattern of asymmetry for the frontal lobe (right < left) and a smaller right frontal volume (prefrontal specifically) in the ADHD subjects most severely impaired. Right caudate and frontal measures were inversely correlated. CONCLUSIONS: ADHD is associated with fronto-striatal abnormalities, which may be explicable via extant neurodevelopmental theories. Enlargement of the right caudate nucleus may suggest the failure of a process of synaptic 'pruning' by which attentional functions could be improperly transferred from the basal ganglia to frontal regions during development.

[Fragile X syndrome and mental retardation]. / Síndrome de frágil-X y retraso mental.

INTRODUCTION: Fragile-X syndrome is characterized by the presence of a fragile site (gap) on Xq 27.3 and the transcriptional inhibition of a mRNA protein-binding gene called FMR-1. Neuropsychological features include cognitive impairment, attention deficit disorder with and without hyperactivity, and impairment of visuospatial functions, language and frontal executive functions. In the present paper, other cytogenetic and phenotype characteristics, associate disorders, neurological and neuroimaging studies are revised. CLINICAL CASES: We describe two siblings that illustrate the pattern of neurocognitive and behavioural trends of the Fragile X syndrome, and sex differences. DISCUSSION AND CONCLUSIONS: These two cases emphasize the need for performing a cytogenetic diagnostic in patients with mental retardation, of unknown etiology, and with a familiar history of mental retardation.

[Williams syndrome: memory, visuospatial and visuoconstructive functions]. / Sindrome de Williams: memoria, funciones visuoespaciales y funciones visuoconstructivas.

INTRODUCTION: Williams syndrome (WS) is a dominant autosomal genetic syndrome resulting from a microdeletion on chromosome 7. This deletion gives rise to certain characteristic physical traits, systemic pathologies and a cognitive behavioural pattern that is characterised by the relative preservation of linguistic abilities with very striking visuospatial deficits. CASE REPORTS: We describe the neuropsychological features of three patients with WS, diagnosed by means of a cytogenetic study, and their mnemonic functions and visuospatial skills are explored. CONCLUSIONS: The results obtained in the study of these three patients reinforce the idea, already acknowledged in the literature, of the marked visuospatial difficulties. They also account for the need for an early diagnosis and an extensive knowledge of the cognitive profile of these patients so as to allow the planning of a stimulation that strengthens the cognitive possibilities of children suffering from this syndrome as much as possible.

[Sustained attention in the preclinical phase of Alzheimer's disease]. / La atencion sostenida en la fase preclinica de la enfermedad de Alzheimer.

INTRODUCTION: Deterioration of attention in the preclinical phase of dementia of Alzheimer s type (DAT) is not very well known neither available studies are conclusive. OBJECTIVE: We outline if would be possible to identify a deficit of sustained attention in preclinical phase of DAT and if this attentional dysfunction could help to identify those patients, referred by subjective memory complaints (SMC), who will progress in a few years to DAT. PATIENTS AND METHODS: We compared basal exploration in a task of sustained attention (CPT) of 70 patients referred by SMC and followed longitudinally for 2 years. Twenty seven patients developed probable DAT and forty three remained clinically stable. RESULTS: Patients who will be diagnosed 2 years later with DAT performed significantly more poorly than patients who did not develop DAT. Patients who will be diagnosed 2 years later with DAT made a higher number of omission errors and obtained a lower number of correct responses. CONCLUSION: CPT paradigm is a vigilance task that detects deterioration of sustained attention in the preclinical phase of DAT and could be an objective indicator of the cognitive decline in the preclinical phase of Alzheimer s disease.

Chronic effects of dopaminergic replacement on cognitive function in Parkinson's disease: a two-year follow-up study of previously untreated patients.

BACKGROUND: The cognitive effects of dopaminergic treatment in Parkinson's disease (PD) are still controversial. OBJECTIVE: To evaluate, in previously untreated patients with PD, whether chronic dopaminergic stimulation produces significant cognitive changes; whether they are sustained beyond the period of a few months; and whether the cognitive status of two motor-comparable groups is differently affected by levodopa and pergolide. DESIGN AND SUBJECTS: Parallel, randomized open study with blind neuropsychologic evaluation of 20 consecutive de novo patients with PD before and 3, 6, 12, 18, and 24 months after monotherapy with levodopa (n = 10) or pergolide (n = 10; 6-month monotherapy; pergolide + levodopa thereafter). RESULTS: Both treatments were associated with a significant improvement in motor scores and in tests assessing learning and long-term verbal and visual memory, visuospatial abilities, and various frontal tasks. While improvement in motor scores persisted, improvement in activities of daily living and in semantic fluency, Luria's rhythm and motor and long-term memory tests was not sustained at the 24-month examination. Further, performance on attentional, short-term memory, and the Stroop tests did not change over the course of the study. CONCLUSIONS: Both treatments were associated with incomplete but long-lasting (18 mos) improvement in many cognitive tasks which declined thereafter, suggesting that dopaminergic replacement is not enough to compensate for all cognitive deficits of PD.

[Cognitive and functional decline in the stage previous to the diagnosis of Alzheimers disease]. / Deterioro cognitivo y funcional en la fase previa al diagnóstico de enfermedad de Alzheimer.

INTRODUCTION: The decline in the phase prior to diagnosis of Alzheimers disease (AD) is not well known, although this knowledge is necessary to evaluate the efficiency of new drugs that can influence in disease course prior to diagnosis. OBJECTIVE: To contribute to better knowledge of the decline prior to diagnosis, we have investigated the cognitive and functional deterioration for 2-3 years before the probable AD diagnosis was established. PATIENTS AND METHODS: We compared results obtained by 17 control subjects and 27 patients at the time of diagnosis of a probable AD with results obtained 2-3 years before (interval of 27.7 4 months). We compared memory functions (logical, recognition, learning and autobiographical memory), naming, visual and visuospatial gnosis, visuoconstructive praxis, verbal fluency and the Mini-Mental State Examination (MMSE), Informant Questionnaire and Blessed's Scale scores. RESULTS: Performance of control subjects did not change. AD patients showed a significant decline in scores, except for verbal fluency. In order of importance, cognitive decline was more marked in scores of learning memory, visuospatial gnosis, autobiographical memory and visuoconstructive praxis. CONCLUSIONS: Decline prior to diagnosis of AD is characterized by an important learning memory impairment. Deterioration of visuospatial gnosis and visuoconstructive praxis is greater than deterioration of MMSE and Informant Questionnaire scores.

Efectos en el sistema cardiovascular y en el hueso / No disponible

No disponible