Decreased GABA-A binding on FMZ-PET in succinic semialdehyde dehydrogenase deficiency

OBJECTIVE

Succinic semialdehyde dehydrogenase (SSADH) deficiency is an autosomal recessive disorder of GABA metabolism characterized by elevated levels of GABA and gamma-hydroxybutyric acid. Clinical findings include intellectual impairment, hypotonia, hyporeflexia, hallucinations, autistic behaviors, and seizures. Autoradiographic labeling and slice electrophysiology studies in the murine model demonstrate use-dependent downregulation of GABA(A) receptors. We studied GABA(A) receptor activity in human SSADH deficiency utilizing [(11)C]-flumazenil (FMZ)-PET.

METHODS

FMZ binding was measured in 7 patients, 10 unaffected parents, and 8 healthy controls. Data analysis was performed using a reference region compartmental model, with time-activity curve from pons as the input function. Relative parametric binding potential (BP(ND)) was derived, with MRI-based pixel by pixel partial volume correction, in regions of interest drawn on coregistered MRI.

RESULTS

In amygdala, hippocampus, cerebellar vermis, frontal, parietal, and occipital cortex, patients with SSADH deficiency had significant reductions in FMZ BP(ND) compared to parents and controls. Mean cortical values were 6.96 +/- 0.79 (controls), 6.89 +/- 0.71 (parents), and 4.88 +/- 0.77 (patients) (F ratio 16.1; p < 0.001). There were no differences between controls and parents in any cortical region.

CONCLUSIONS

Succinic semialdehyde dehydrogenase (SSADH) deficient patients show widespread reduction in BZPR binding on [(11)C]-flumazenil-PET. Our results suggest that high endogenous brain GABA levels in SSADH deficiency downregulate GABA(A)-BZPR binding site availability. This finding suggests a potential mechanism for neurologic dysfunction in a serious neurodevelopmental disorder, and suggests that PET may be useful to translate studies in animal models to human disease.

Economic impact of dementia in developing countries: an evaluation of costs of Alzheimer-type dementia in Argentina

BACKGROUND

There is no previous information about economic costs of Alzheimer's disease (AD) in South America. The objective of this study was to evaluate the costs of AD in Argentina.

METHODS

Eighty community-dwelling patients, 20 institutionalized AD patients and their respective primary caregivers, and 25 healthy elderly subjects participated in this study. The cognitive and neuropsychiatric impairments and severity of dementia were assessed with the Mini-mental State Examination, Neuropsychiatric Inventory and Clinical Dementia Rating, respectively. A structured interview about health and health-care resources used during the past 3 months was administered to family caregivers. The time devoted by carers to looking after the patients and the caregiver burden (Zarit's Burden Interview) were recorded.

RESULTS

The annual direct costs of the disease increased with cognitive deterioration from US$3420.40 in mild to US$9657.60 in severe AD, and with institutionalization (US$3189.20 outpatient vs. US$14,447.68 institutionalized). Most direct costs were paid for by the family.

CONCLUSIONS

With the projected increase in the number of persons at risk for developing AD in emerging countries, the family cost of the disease will be significant. Dementia costs should be a matter of analysis when health policies are being designed in developing countries.

Behavioral flexibility impairment with negative feedback in refractory temporal lobe epileptic patients with unilateral amygdala and hippocampal resection

INTRODUCTION

Patients with amygdala dysfunction generally have behavioral impairment. Temporal lobe surgery might be a model of study of unilateral amygdala resection. The objective of this study was to evaluate behavioral flexibility in epileptic patients who undergo amygdala resection for epilepsy surgery and evaluate its relationship with their neuropsychiatric symptoms.

MATERIAL AND METHODS

Ten epileptic patients who underwent amygdala and hippocampal resection (6 left and 4 right) matched by age and educational level with 10 healthy controls were tested with an extensive neuropsychological and neuropsychiatric battery. Psychiatric symptomatology was measured with the positive and negative syndrome scale (PANSS) and the Beck depression inventory. To assess behavioral flexibility the emotion-related visual reversal-learning task (O'Doherty et al., 2001) and the gambling task (Bechara et al., 1994) were used.

RESULTS

Patient's mean scores were: Beck: 8 +/- 1.5; PANSS positive: 10 +/- 1.3, and negative: 14.4 +/- 2.2; intellectual quotient (IQ): 101.4 +/- 6.3; category number in Wisconsin card sorting test: 4.6 +/- 2.4. The emotion-related visual reversal-learning task showed significance differences in the number of reversion: healthy controls: 9.3; epileptic patients: 4.23 (p < 0.001); in the number of trials to the first reversion: healthy controls: 5; epileptic patients: 23.42 (p < 0.05). There was no correlation between reversion and depression, PANSS and IQ.

CONCLUSIONS

Patients with epilepsy who undergo unilateral hippocampal and amygdala resection appear to have alterations in the reversion capacity with an emotional component that would explain the lack of behavior flexibility that they sometimes have and that are not related with either the isolated presence of executive alterations or low intellectual quotient.

Neuropsychiatric symptoms as a predictor of caregiver burden in Alzheimer's disease

AIMS

Patients with Alzheimer's disease need assistance and supervision of their daily activities. They survive for protracted periods of time, placing an extensive burden of care on the caregiver prior to the patient's death. The present study addressed the predictive value of behavior-related burden on Alzheimer's disease caregivers.

PARTICIPANTS

82 patients with probable Alzheimer's (73.7 +/- 8.1 years), and their primary caregivers (59.6 +/- 14.8 years, 81.5% women), were assessed.

METHODS

Cognitive impairment, neuropsychiatric symptoms, and dementia severity were assessed with Mini Mental State Examination (MMSE), Neuropsychiatric Inventory (NPI), and Clinical Dementia Rating (CDR), respectively. Caregivers were given Zarit's Burden Interview and Carer Activity Inventory.

RESULTS

Neuropsychiatric symptoms like delusions, hallucinations, restlessness, anxiety, euphoria, disinhibition, unusual motor behavior, sleep disturbances, and appetite alterations were the best caregiver burden predictors (NPI r = 0.482, p < 0.001). No correlation with cognition, disease stage, or negative neuropsychiatric symptoms (depression and apathy) was found.

CONCLUSION

Increased caregiver burden was related to increased levels of patient behavioral disturbance. Of these symptoms, hallucinations, unusual (motor) behavior, and abnormal behavior at nighttime were the most significant. No correlation with neuropsychiatric symptoms such as apathy and depression was found. This may have relevance to appropriate interventions for caregivers.

[Cognition in dysthymia]

Depression is named as one of the most prevalent Mental Health problem, affecting almost 10 % of the population. According to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) different subtypes are included. Dysthymic Disorder is characterized by a depressed mood for most of the day, for more days than not, as indicated either by subjective account or observation by others, for at least 2 years. The aim of this study was to investigate the neuropsychological profile of dysthymic disorder. Ninety three patients fulfilling criteria for dysthymia were examined on a variety of cognitive tasks, neurological exam and a semi-structured psychiatric interview. Forty one non-depressed individuals served as controls. Significant differences between groups were found in digit span; immediate and delayed recall of a story; and semantic and phonologic fluency. Logic memory was worse than serial learning task, and has a correlation with attention deficit and depressive features.

CONCLUSIONS

This results indicate that the neuropsychological performance of patients with dysthymic disorder exhibit impairments in attention and memory. Attentional deficits appear to be the key of cognitive deficits in dysthymia.

[Neuropsychological tools for the study of depression]

Depression is a common disorder, affecting approximately one in ten of the population at some time in their lives. The nature and extent of such changes, however, is less clear, and their specificity to mood disorder, their existence before the onset of affective symptoms, their etiology and their relation ship to underlying neuroanatomical abnormalities remain poorly understood. Our objective is to present a comprehensive review of the existing neuropsychological literature on bipolar affective disorder, mayor depression and the differential diagnosis between geriatric depression and the depression as early symptom of Alzheimer's disease. The most critical neuropsychological assessment to study this patients will be discussed. Depression is associated with dysexecutive syndrome which correlate with fronto subcortical diseases. Cognitive impairment include attention disorders, memory difficulties type forgetfulness and executive dysfunction (planning and executions of complex behaviors, monitoring of performance, feedback, decision making etc). Cortical neuropsychological profile in a depressive patients represent Alzheimer's disease associate. Neuropsychological assessment is useful to detect both different cognitive profiles (Cortical vs Subcortical).

[Screening for mild cognitive impairment: usefulness of the 7-Minute Screen Test]

INTRODUCTION

The <<7- Minute Screen>> is a neurocognitive screening test for the detection of Alzheimer's disease (AD) patients in primary care settings. It consists of 4 brief subtests (orientation, memory, visuoconstruction and verbal fluency) and provides a broader neuropsychological profile than other widely used screening tests, The aim of the present study was to study the usefulness of this screening test for the detection of Mild Cognitive Impairment (MCI).

METHODS

Thirty-two patients with probable AD (NINCDS-ADRDA criteria), 25 patients with MCI, and 35 healthy control subjects, matched for age and education, underwent a comprehensive neuropsychological battery and the Rio-de-la-Plata version of the 7-Minute Screen. RESULTS. This test showed 93 % sensitivity and 97% specificity in detecting mild-moderate Alzheimer's disease MMSE<24), but it exhibited a substantially decreased sensitivity (28 %) in its ability to detect MCI in AD (MMSE >2 4 ).

CONCLUSION

The screening batteries do not replace a m o re compre h e n s i ve neuro psychological assessment. Th ey are useful in detecting patients with mild dementia, but caution must be the rule when considering a diagnosis of MCI.

[A shortened form of the Spanish Boston naming test: a useful tool for the diagnosis of Alzheimer's disease]

INTRODUCTION

The Boston Naming Test (BNT) is the most frequently used test of confrontation naming. Due to its length, several abbreviated forms have been proposed.

OBJECTIVE

The aim of the study was to develop a short form for the Spanish version of the BNT that could detect early semantic changes in Alzheimer s disease (AD).

PATIENTS AND METHODS

One hundred and three patients with diagnosis of probable AD (NINCDS ADRDA criteria), with GDS< 5 and 143 normal subjects, matched for age and education, were studied. Subjects with <4 years of education were excluded. No subject had any history of neurological of psychiatric disorders or alcohol abuse. All participants underwent a comprehensive neuropsychological assessment which included the 60 item Spanish version of the BNT. The sensibility and specificity of each item and demographic effect s variability were calculated (ANOVA). Those 12 figures with the highest sensibility and specificity which showed no significant educational or age variation were administered to all participants. The Spearman correlation coefficient was used.

RESULTS

Mean score for the control group was 11 (standard deviation: 1.16). No significant effects for age (r= 0.14574) or education (r= 0.101293) were found. The sensibility and specificity for correctly diagnosing AD was 85% and 94% respectively, similar to the longest version.

CONCLUSION

This 12 item version of the BNT can be a useful instrument for a rapid screening of AD, as it is as sensible and specific as the 60 item version, and it is not influenced by age or education.

Improving image contrast using principal component analysis for subsequent image segmentation

This article presents a technique for improving MR image contrast by linearly combining multiple MR images with different tissue contrast. The weighting coefficients of the linear combination are derived using principal component analysis. The contrast-enhanced composite image is segmented subsequently using gray level-based 1D segmentation methods. The technique reduces a multispectral image set to composite eigenimages and allows application of appropriate 1D segmentation methods that do not have equivalent counterparts in multispectral methods.

[Spanish verbal fluency. Normative data in Argentina]

Letter and category fluency tasks are used to assess semantic knowledge, retrieval ability, and executive functioning. The original normative data have been obtained mainly from English speaking populations; there are few papers on norms in other languages. The purpose of this study was to collect normative scores in Argentina and to evaluate the effects of sex, age, education and cognitive status on the letter and category fluency tasks, in 266 healthy Spanish-speaking participants (16 to 86 years). Mean education span was 12.8 +/- 4 years. In each subject a neuropsychological battery (Minimental State Exam, Signoret Memory Battery, Boston Naming Test and Trail Making Test) was carried out as well as category fluency (naming animals in one minute) and letter fluency (words beginning with letter "p" in one minute). The sample was arranged into a group of subjects with less than 45 years and further groups up to 10 more years, until 75 years (or more) with three different levels of education. Significant effects were found for age, education, and Minimental State Exam on performance of both fluencies. Mean performance scores are presented for each group to be used in Argentina.

Sources on the anterior and posterior banks of the central sulcus identified from magnetic somatosensory evoked responses using multistart spatio-temporal localization

A Multi-Start Spatio-Temporal (MSST) multidipole localization algorithm was used to study sources on the anterior and posterior banks of the central sulcus localized from early somatosensory magnetoencephalography (MEG) responses. Electrical stimulation was applied to the right and left median nerves of 8 normal subjects. Two sources, one on the anterior and one on the posterior bank of the central sulcus, were localized from 16 data sets (8 subjects, 2 hemispheres). Compared with the more traditional practice of single-dipole fits to peak latencies, MSST provided more reliable source locations. The temporal dynamics of the anterior and posterior central sulcus sources, obtained using MSST, showed considerable temporal overlap. In some cases, the two sources appeared synchronous. On the other hand, in the traditional single-dipole peak-latency fit approach, there is no time course other than a focal dipole moment activated only at the selected peak latency. The same group of subjects also performed a motor task involving index-finger lifting; the anterior central sulcus source obtained from electrical median nerve stimulation localized to the same or similar region in the primary motor area identified from the finger-lift task. The physiological significance of the anterior central sulcus source is discussed. The findings suggest that one can test the integrity of cortical tissue in the region of primary motor cortex using electrical somatosensory stimulation.

Sources on the anterior and posterior banks of the central sulcus identified from magnetic somatosensory evoked responses using multistart spatio-temporal localization

A Multi-Start Spatio-Temporal (MSST) multidipole localization algorithm was used to study sources on the anterior and posterior banks of the central sulcus localized from early somatosensory magnetoencephalography (MEG) responses. Electrical stimulation was applied to the right and left median nerves of 8 normal subjects. Two sources, one on the anterior and one on the posterior bank of the central sulcus, were localized from 16 data sets (8 subjects, 2 hemispheres). Compared with the more traditional practice of single-dipole fits to peak latencies, MSST provided more reliable source locations. The temporal dynamics of the anterior and posterior central sulcus sources, obtained using MSST, showed considerable temporal overlap. In some cases, the two sources appeared synchronous. On the other hand, in the traditional single-dipole peak-latency fit approach, there is no time course other than a focal dipole moment activated only at the selected peak latency. The same group of subjects also performed a motor task involving index-finger lifting; the anterior central sulcus source obtained from electrical median nerve stimulation localized to the same or similar region in the primary motor area identified from the finger-lift task. The physiological significance of the anterior central sulcus source is discussed. The findings suggest that one can test the integrity of cortical tissue in the region of primary motor cortex using electrical somatosensory stimulation.