Altered cerebral perfusion measured by SPECT in relatives of patients with schizophrenia. Correlations with memory and P300

BACKGROUND Genetic studies in schizophrenia are hampered by the complex heterogeneous clinical phenotype. Biological variables identified as trait markers of risk could clarify the mode of inheritance, define clinical subgroups and provide clues about aetiology. AIMS To use single photon emission computed tomography (SPECT) to compare brain perfusion maps in patients with schizophrenia (n = 19), their asymptomatic 'high-risk' relatives (n = 36) and control subjects (n = 34) and to examine the relationships between imaging, memory and P300 event-related potential. METHOD SPECT, memory tests and P300 recording were carried out. RESULTS In the patients with schizophrenia and their relatives, perfusion was reduced in left inferior prefrontal and anterior cingulate cortex and increased bilaterally in a subcortical region. Perfusion significantly correlated with verbal memory and P300 amplitude in left inferior prefrontal cortex and with P300 latency in anterior cingulate cortex. CONCLUSIONS Medication- and symptom-free relatives had altered regional perfusion intermediate between subjects with schizophrenia and controls. Impaired perfusion, verbal memory and P300 appear to be related traits associated with an increased risk of illness

Memory impairment in out-of-hospital cardiac arrest survivors is associated with global reduction in brain volume, not focal hippocampal injury

Background and Purpose -- More than 30% of out-of-hospital cardiac arrest (OHCA) survivors suffer significant memory impairment. The hippocampus may be vulnerable to hypoxic injury during cardiac arrest. The purpose of this study was to determine whether selective hippocampal injury is the substrate for this memory impairment. Methods -- Seventeen OHCA survivors and 12 patients with uncomplicated myocardial infarction were studied. OHCA survivors were divided into those with impaired and intact memory. Memory was assessed by use of the Rivermead Behavioural Memory Test and Doors and People Test. MRI was used to determine intracranial, whole-brain, amygdala-hippocampal complex, and temporal lobe volumes. Brain structure was also examined by statistical parametric mapping. Results -- Left amygdala-hippocampal volume was reduced in memory-impaired OHCA victims compared with control subjects (mean 3.93 cm3 and 95% CI 3.50 to 4.36 cm3 versus mean 4.65 cm3 and 95% CI 4.37 to 4.93 cm3; P=0.002). Left temporal lobe and whole-brain volumes were also reduced. There were no differences in amygdala-hippocampal volume indexed against ipsilateral temporal lobe volume. Significant correlations were observed between total brain volume and Rivermead Behavioural Memory Test (r=0.56, P less than 0.05) and Doors and People Test (r=0.67, P less than 0.01) scores in OHCA survivors. Both recall and recognition were compromised in memory-impaired subjects. Statistical parametric mapping did not detect focal brain abnormalities in these subjects. Global cerebral atrophy was confirmed by qualitative assessment. Conclusions -- Memory impairment in OHCA survivors is associated with global cerebral atrophy, not selective hippocampal damage. Rehabilitation protocols need to account for the global nature of the brain injury

Padrões de ativação cerebral em idosos sadios durante tarefa de memória verbal de reconhecimento: a single-photon emission computerized tomography study Brain activation patterns during verbal recognition memory in elderly healthy volunteers

INTRODUÇÃO: Estudos que utilizam as técnicas de PET, SPECT e ressonância magnética funcional têm permitido o mapeamento dos circuitos cerebrais ativados durante diversas tarefas cognitivas. O campo da memória declarativa tem sido um dos mais intensamente estudados. No presente estudo, usa-se a técnica de mapeamento do fluxo sangüíneo cerebral regional (FSCr) por SPECT para investigar mudanças na atividade cerebral durante uma tarefa de memória episódica, em voluntários idosos sadios (n=15). MÉTODOS: Duas avaliações de SPECT foram realizadas na mesma sessão, usando a técnica de dose dividida do traçador 99 m-Tc-HMPAO. Medidas de FSCr foram registradas durante uma tarefa de reconhecimento de material verbal previamente aprendido e durante uma tarefa-controle mais simples. Comparações de FSCr foram realizadas automaticamente, utilizando o programa Statistical Parametric Mapping (SPM). RESULTADOS: Observou-se aumento de FSCr durante a tarefa de memória em várias regiões cerebrais, incluindo: córtex pré-frontal lateral bilateralmente (mais acentuadamente à esquerda); porções posteriores e mediais de córtex parieto-occipital à esquerda; hemisférios cerebelares bilateralmente; e córtex temporal lateral bilateralmente (p<0,001, não corrigido para comparações múltiplas). Foram observados também focos inesperados de diminuição de FSCr em cíngulo posterior direito, córtex orbitofrontal esquerdo, córtex temporal inferior direito e vérmis cerebelar esquerdo (p<0,05, corrigido para comparações múltiplas). CONCLUSÃO: Esses resultados sugerem que circuitos neuronais multifocais são engajados durante memória de reconhecimento e replicam localizações cerebrais descritas anteriormente na literatura. O uso desse protocolo em pacientes com transtornos neuropsiquiátricos poderá permitir a investigação de anormalidades cerebrais subjacentes aos déficits de memória presentes nesses transtornos.<br>INTRODUCTION: PET, SPECT and functional magnetic resonance imaging studies have allowed the delineation of brain circuits activated during several types of cognitive tasks. The field of declarative memory has been one of the most extensively investigated. In the present study, the regional cerebral blood flow (rCBF) SPECT technique was used to investigate changes in brain activity during a verbal memory task in a group of elderly healthy volunteers (n=15). METHODS:Two SPECT acquisitions were performed in the same session, using the split-dose 99mTc-HMPAO technique. Measures of rCBF were taken during a recognition memory task and a simpler control task. Between-task comparisons were performed automatically using the Statistical Parametric Mapping (SPM) program. RESULTS: Increased rCBF during the memory task was seen in several brain regions, including: the lateral prefrontal cortex on both hemispheres (more intensely on the left side); posterior and medial portions of the left occipital and parietal cortices; the right and left cerebellar hemispheres; and the right and left lateral temporal cortex (p<0.001, uncorrected for multiple comparisons). Unexpected foci of decreased rCBF were seen in the right posterior cingulate cortex, left orbitofrontal cortex, right inferior temporal cortex and left cerebellar vermis (p<0.05, corrected for multiple comparisons). CONCLUSION:These results suggest that multifocal neural circuits are engaged during recognition memory, and replicate locations seen in previous studies in the literature. The use of the protocols described here in patients with neuropsychiatric disorders may allow investigation of brain abnormalities underlying the memory deficits seen in these disorders