Lynn M. Grattan

Frontal lobe and frontal-striatal substrates for different forms of human cognitive flexibility.

Frontal lobe and basal ganglia lesions have been associated with similar cognitive impairments, although their specialized roles in behavior are likely to be different. We examined whether these structures mediate distinctive or overlapping aspects of a complex behavioral process that has been associated with both neural sites, i.e. cognitive flexibility. Patients with focal ischemic lesions to the frontal lobe and basal ganglia were compared on two forms of cognitive flexibility: (1) shifting response set (i.e. reactive flexibility), and (2) producing a diversity of ideas (i.e. spontaneous flexibility). Results indicated that frontal lobe and basal ganglia damage each caused a similar degree of impairment in reactive flexibility, both groups performing at a significantly lower level than posterior cortical lesion and normal comparison groups. However, frontal lobe damage markedly disturbed spontaneous flexibility, while performance after basal ganglia lesion was significantly higher and comparable to posterior cortical lesions. Findings suggest that the frontal lobe and basal ganglia participate differently in the neural substrate of cognitive flexibility. The frontal lobe appears to mediate spontaneous flexibility. The production of diverse ideas may require direct cortical-cortical interactions by the frontal lobe in order to access knowledge systems with novel strategies that transcend the most common semantic linkages. In contrast the corticostriate system appears to mediate reactive flexibility, as the frontal lobe, basal ganglia and their interconnections are required for its operation.

Complex partial status epilepticus accompanied by serious morbidity and mortality

Nonconvulsive status epilepticus (NCSE) accounts for approximately 20% of all status epilepticus (SE).Although convulsive SE is recognized as a medical emergency, prompt diagnosis and treatment of patients with NCSE is often not emphasized because its consequences are thought to be benign. We report 10 patients with persistent neurologic deficits or death after well-documented NCSE in the form of complex partial status epilepticus (CPSE). All patients had prolonged CPSE lasting 36 hours or longer, as documented by clinical and EEG findings. Causes for CPSE were preexisting epilepsy with partial and secondarily generalized seizures (3 patients), vascular disease (2 patients), encephalitis (2 patients), and metabolic disease (1 patient); causes were unknown for two patients. Poor outcomes identified included persistent (lasting at least 3 months) or permanent cognitive or memory loss (5 patients), cognitive or memory loss plus motor and sensory dysfunction (3 patients), and death (3 patients). NCSE in the form of CPSE is not a benign entity. Serious morbidity and mortality may occur due to the adverse effects of prolonged seizures and as a result of acute brain disorders that precipitate the seizures. NEUROLOGY 1995;45: 1499-1504

Cognitive impairment in hip fracture patients: timing of detection and longitudinal follow-up.

Objectives: To examine the prevalence, incidence, persistence, predictors, and outcomes of cognitive impairment after hip fracture.

Low level methylmercury exposure affects neuropsychological function in adults

BackgroundThe neurotoxic effects of methylmercury (MeHg) have been demonstrated in both human and animal studies. Both adult and fetal brains are susceptible to the effects of MeHg toxicity. However, the specific effects of adult exposures have been less well-documented than those of children with prenatal exposures. This is largely because few studies of MeHg exposures in adults have used sensitive neurological endpoints. The present study reports on the results of neuropsychological testing and hair mercury concentrations in adults (>17 yrs) living in fishing communities of Baixada Cuiabana (Mato Grosso) in the Pantanal region of Brazil.MethodsA cross-sectional study was conducted in six villages on the Cuiaba River. Participants included 129 men and women older than 17 years of age. They were randomly selected in proportion to the age range and number of inhabitants in each village. Questionnaire information was collected on demographic variables, including education, occupation, and residence history. Mercury exposure was determined by analysis of hair using flameless atomic absorption spectrophotometry. The neurocognitive screening battery included tests from the Wechsler Memory Scale and the Wechsler Adult Intelligence Scale, Concentrated Attention Test of the Toulouse-Pierron Factorial Battery, the Manual Ability Subtests of the Tests of Mechanical Ability, and the Profile of Mood States.ResultsMercury exposures in this population were associated with fish consumption. The hair mercury concentration in the 129 subjects ranged from 0.56 to 13.6 μg/g; the mean concentration was 4.2 ± 2.4 micrograms/g and the median was 3.7 μg/g. Hair mercury levels were associated with detectable alterations in performance on tests of fine motor speed and dexterity, and concentration. Some aspects of verbal learning and memory were also disrupted by mercury exposure. The magnitude of the effects increased with hair mercury concentration, consistent with a dose-dependent effect.ConclusionsThis study suggests that adults exposed to MeHg may be at risk for deficits in neurocognitive function. The functions disrupted in adults, namely attention, fine-motor function and verbal memory, are similar to some of those previously reported in children with prenatal exposures.

Frontal lobe damage in children and adults: A comparative review

Clinical and experimental studies of focal frontal lobe damage in children and adults are reviewed and analyzed. Although each literature has traditionally been treated separately, we argue that they share many common issues and that comparative analysis reveals both contrasting and complementary, findings that provide the foundation for a life‐span view of frontal lobe maturation and operation. Furthermore, each literature offers unique data regarding frontal lobe damage and recovery. Integration of these diverse findings is important to clinical and theoretical advances, and leads to the common view that the frontal lobes and their connections are critical to the development and maintenance of human adjustment and adaptive behavior throughout life.

The Early Psychological Impacts of the Deepwater Horizon Oil Spill on Florida and Alabama Communities

Background Although public concern has focused on the environmental impact of the Deepwater Horizon oil spill, the public health impact on a broad range of coastal communities is minimally known. Objective We sought to determine the acute level of distress (depression, anxiety), mechanisms of adjustment (coping, resilience), and perceived risk in a community indirectly impacted by the oil spill and to identify the extent to which economic loss may explain these factors. Methods Using a community-based participatory model, we performed standardized assessments of psychological distress (mood, anxiety), coping, resilience, neurocognition, and perceived risk on residents of fishing communities who were indirectly impacted (n = 71, Franklin County, Florida) or directly exposed (n = 23, Baldwin County, Alabama) to coastal oil. We also compared findings for participants who reported income stability (n = 47) versus spill-related income loss (n = 47). Results We found no significant differences between community groups in terms of psychological distress, adjustment, neurocognition, or environmental worry. Residents of both communities displayed clinically significant depression and anxiety. Relative to those with stable incomes, participants with spill-related income loss had significantly worse scores on tension/anxiety, depression, fatigue, confusion, and total mood disturbance scales; had higher rates of depression; were less resilient; and were more likely to use behavioral disengagement as a coping strategy. Conclusions Current estimates of human health impacts associated with the oil spill may underestimate the psychological impact in Gulf Coast communities that did not experience direct exposure to oil. Income loss after the spill may have a greater psychological health impact than the presence of oil on the immediately adjacent shoreline.

Long-term psychological consequences of childhood frontal lobe lesion in patient DT

Patient DT was examined 26 years after she acquired focal frontal lobe damage at 7 years of age. This report focused on several aspects of psychological outcome, including the empirical study of social development into early adulthood. Standardized measures of empathy, psychosocial development, and personality were analyzed, along with a moral judgment interview and patterns of adult social behavior. Results indicated that DT has a very limited capacity for empathic understanding, inadequate identity development, difficulties in vocational adjustment, and a concrete level of moral reasoning. Her social behavior and profile of test scores suggest that social development and adaptation have been arrested at early adolescent levels. We conclude that early frontal lobe damage has profound effects on social development, and that the frontal lobes provide a crucial neural substrate for social maturation.

Altered serial position learning after frontal lobe lesion

The serial position function is a powerful and highly reliable feature of human learning, with well-described primacy and recency effects. We tested the hypothesis that frontal lobe lesions in patients would disrupt the serial position function since such patients are known to have disturbed temporal ordering, learning in the presence of interference, encoding and organizational approaches to learning. Performance was compared in patients with focal, acquired lesions of frontal and non-frontal cortices, using a standardized paradigm of verbal list learning. Results indicated a similar pattern of performance on first trial learning for the two groups. However, across learning trials, frontal lesion subjects failed to maintain significant primacy and recency effects. Non-frontal lesion subjects consistently showed the expected U-shaped serial position curve across all trials. Subjective organization in learning was particularly deficient in the dorsolateral frontal lesion subjects. We propose that serial position effects are qualitatively different after frontal lobe lesion, being transitory and prone to alteration by the cumulative effects of disturbed temporal-spatial processing across learning trials.

“Frontal lobe” utilization behavior associated with paramedian thalamic infarction

Disinhibited, exaggerated responses to objects and environmental cues (utilization behavior) occur predominantly with frontal lobe damage. We report a striking example associated with paramedian thalamic infarction suggesting a thalamofrontal component to environmental interactions that require inhibition, self-monitoring, and cognitive flexibility.

Nonepileptic posttraumatic seizures

Summary: Purpose: Epileptic posttraumatic seizures (PTSs) are a well‐recognized consequence of head injury (HI), but HI and nonepileptic seizures (NESs) have not been related. We describe a significant subset of patients with NESs who had their seizures attributed to HI.