New and Noteworthy Information—May 2014

PET is a promising tool for determining which severely brain damaged individuals in vegetative states have the potential to recover consciousness, according to research published online ahead of print April 16 in Lancet. Investigators examined 81 patients in a minimally conscious state, 41 patients with unresponsive wakefulness syndrome, and four patients with locked-in syndrome. The researchers performed repeated standardized clinical assessments with the Coma Recovery Scale–Revised (CRS-R), cerebral 18F-fluorodeoxyglucose (FDG) PET, and fMRI while the patients performed mental activation tasks. Mental imagery fMRI was less sensitive at diagnosing a minimally conscious state than FDG-PET (45% vs 93%) and had less agreement with behavioral CRS-R scores than FDG-PET (63% vs 85%). 18F-FDG PET correctly predicted outcome in 75 of 102 patients, and fMRI in 36 of 65 patients.

The risk of epilepsy may be heightened significantly among patients with autoimmune diseases, especially children, according to data published online ahead of print March 31 in JAMA Neurology. Researchers conducted a retrospective population-based study using claims from a nationwide employer-provided health insurance plan in the United States. All 2,518,034 participants included in the study were beneficiaries enrolled between 1999 and 2006. The investigators examined the relationship between epilepsy and type 1 diabetes mellitus, psoriasis, rheumatoid arthritis, Graves disease, Hashimoto thyroiditis, Crohn disease, ulcerative colitis, systemic lupus erythematosus, antiphospholipid syndrome, Sjögren syndrome, myasthenia gravis, and celiac disease. The odds ratio of epilepsy was 3.8 among patients with autoimmune diseases and 5.2 among children. Based on their findings, the authors recommended that patients with epilepsy undergo surveillance for autoimmune disease, and vice versa.

Migraineurs whose stress decreases from one day to the next have a significantly increased risk of migraine onset on the subsequent day, according to a study published online ahead of print March 26 in Neurology. Twenty-two patients with migraine participated in a three-month electronic diary study. Participants entered data daily regarding migraine attack experience, as well as subjective stress ratings. Stress was assessed using the Perceived Stress Scale and the Self-Reported Stress Scale. Level of stress was generally not associated with migraine occurrence. Decline in stress from one evening diary to the next was associated with increased migraine onset during the subsequent six, 12, and 18 hours for the Perceived Stress Scale. Decline in stress was associated with migraine onset after controlling for level of stress for all time points.

Patients older than 60 with stroke resulting from blockage of the middle cerebral artery (MCA) benefit from hemicraniectomy, researchers reported March 20 in the New England Journal of Medicine. Investigators randomly assigned 112 patients age 61 or older with malignant MCA infarction to conservative treatment in the ICU or hemicraniectomy. The primary end point was survival without severe disability (defined as a score of 0 to 4 on the modified Rankin scale). The proportion of patients who survived without severe disability was 38% in the hemicraniectomy group, compared with 18% in the control group. This difference resulted from lower mortality in the surgery group (33% vs 70%). Infections were more frequent in the hemicraniectomy group, and herniation was more frequent in the control group.

The FDA has approved Topamax (topiramate) for the prevention of migraine headaches in adolescents ages 12 to 17. Topamax is the first drug with FDA approval for migraine prevention in this age group. The medication is taken daily to reduce the frequency of migraine headaches. A clinical trial that enrolled 103 participants established the safety and effectiveness of Topamax in preventing migraine headaches in adolescents ages 12 to 17. Participants treated with Topamax had a decrease in migraine frequency of approximately 72%, compared with 44% in participants who took placebo. The most common adverse reactions with the approved dose of Topamax (100 mg) were paresthesia, upper respiratory infection, anorexia, and abdominal pain. Topamax is manufactured by Janssen Pharmaceuticals of Titusville, New Jersey.

The FDA has approved Evzio (naloxone hydrochloride injection), a prescription treatment that family members or caregivers can use to treat a person suspected to have had an opioid overdose. Evzio rapidly delivers a single dose of naloxone through a handheld autoinjector that can be carried in a pocket or stored in a medicine cabinet. Evzio provides intramuscular or subcutaneous administration. Once turned on, the device provides verbal instruction about how to deliver the medication. In one pharmacokinetic study of 30 patients, a single Evzio injection provided equivalent naloxone, compared with a single dose of naloxone injection using a standard syringe. Administering Evzio to patients who are opioid dependent may result in severe opioid withdrawal. Evzio is manufactured by kaléo, which is based in Richmond, Virginia.

The International League Against Epilepsy has altered its practical definition of epilepsy per the recommendation of a task force, according to an article published online ahead of print April 14 in Epilepsia. Recognizing the limitations of the practical definition of epilepsy as two unprovoked seizures more than 24 hours apart, the task force proposed that epilepsy be considered to be a disease of the brain defined by any of the following conditions: (1) At least two unprovoked (or reflex) seizures occurring more than 24 h apart; (2) one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (ie, at least 60%) after two unprovoked seizures, occurring over the next 10 years; (3) diagnosis of an epilepsy syndrome.

Older people who have apathy but not depression may have smaller brain volumes than those without apathy, according to data published online ahead of print April 16 in Neurology. Investigators performed cross-sectional analyses of data from 4,354 persons without dementia (average age, 76) participating in a population-based study. Apathy symptoms were assessed with the Geriatric Depression Scale. Brain volumes and total white matter lesion (WML) volume were estimated on 1.5-T MRI using an automated segmentation program. Regional WML load was calculated using a semiquantitative scale. Compared with individuals with fewer than two apathy symptoms, participants with two or more apathy symptoms had significantly smaller gray matter volumes, smaller white matter volumes, and smaller thalamus volumes. The latter individuals also were more likely to have WMLs in the frontal lobe.

The APOE4 gene variant confers a substantially greater risk for Alzheimer’s disease to women than it does to men, researchers reported online ahead of print April 14 in Annals of Neurology. The group performed Cox proportional hazards analysis to compute hazard ratios (HRs) for an APOE-by-sex interaction on conversion in 5,496 healthy individuals and 2,588 patients with mild cognitive impairment (MCI). The investigators also tested the interaction in CSF biomarker levels of 980 subjects from the Alzheimer’s Disease Neuroimaging Initiative. Among controls, male and female carriers were more likely to convert to MCI or Alzheimer’s disease, but the effect was stronger in women (HR, 1.81 for women; HR, 1.27 for men). The interaction remained significant in a predefined subanalysis that was restricted to APOE3/3 and APOE3/4 genotypes.

The size and shape of the nucleus accumbens and the amygdala may differ in young adults who smoke marijuana at least once a week, according to a study published April 16 in the Journal of Neuroscience. Investigators collected high-resolution MRI scans on young adults who used recreational marijuana and on controls. The researchers conducted three independent analyses of morphometry in gray matter density, volume (total brain and regional volumes), and surface morphometry. The study authors found greater gray matter density in marijuana users than in control participants in the left nucleus accumbens extending to the subcallosal cortex, hypothalamus, sublenticular extended amygdala, and left amygdala, even after controlling for age, sex, alcohol use, and cigarette smoking. Trend-level effects were observed for a volume increase in the left nucleus accumbens only.

Neuronal death in Parkinson’s disease may occur when the immune system mistakes neurons for foreign invaders and kills them, according to a study published April 16 in Nature Communications. An examination of postmortem brain tissue revealed major histocompatibility complex class I (MHC-1) proteins in catecholaminergic substantia nigra and locus coeruleus neurons. When researchers conducted in vitro experiments with mouse neurons and human neurons created from embryonic stem cells, they found that under certain circumstances, including conditions that occur in Parkinson’s disease, the neurons use MHC-1 to display antigens. Among the different types of neurons tested, the two types affected in Parkinson’s disease were far more responsive than other neurons to signals that triggered antigen display. The researchers also confirmed that T cells recognized and attacked neurons displaying specific antigens.

People who have had a stroke who consistently control their blood pressure may reduce the likelihood of a second stroke by more than half, according to research published online ahead of print March 27 in Stroke. In a post hoc analysis, 3,680 individuals with recent stroke who were followed up for two years were grouped according to the proportion of visits during which their blood pressure was controlled (ie, <140/90 mm Hg). Consistency of blood pressure control affected outcomes in individuals with baseline systolic blood pressure greater than 132 mm Hg. Among individuals with baseline systolic blood pressure higher than 153 mm Hg, risks of stroke, myocardial infarction, or vascular death were lower in those with blood pressure controlled during 75% or more visits, versus less than 25% of visits.

Individuals between ages 18 and 24 who occasionally use stimulant drugs may have impaired neuronal activity in the parts of the brain associated with anticipatory functioning, according to research published March 26 in the Journal of Neuroscience. Investigators recruited 158 nondependent occasional stimulant users and 47 stimulant-naive controls. Participants completed a stop signal task while undergoing functional MRI. Compared with controls, occasional stimulant users showed attenuated neural activation related to the magnitude of probabilistic expectations of inhibitory demand in several areas, including the left prefrontal cortex and left caudate. The results indicate that clinicians may be able to use brain activity patterns as a means of identifying at-risk youth long before they have any obvious outward signs of addictive behaviors, according to the investigators.

—Erik Greb

PET is a promising tool for determining which severely brain damaged individuals in vegetative states have the potential to recover consciousness, according to research published online ahead of print April 16 in Lancet. Investigators examined 81 patients in a minimally conscious state, 41 patients with unresponsive wakefulness syndrome, and four patients with locked-in syndrome. The researchers performed repeated standardized clinical assessments with the Coma Recovery Scale–Revised (CRS-R), cerebral 18F-fluorodeoxyglucose (FDG) PET, and fMRI while the patients performed mental activation tasks. Mental imagery fMRI was less sensitive at diagnosing a minimally conscious state than FDG-PET (45% vs 93%) and had less agreement with behavioral CRS-R scores than FDG-PET (63% vs 85%). 18F-FDG PET correctly predicted outcome in 75 of 102 patients, and fMRI in 36 of 65 patients.

The risk of epilepsy may be heightened significantly among patients with autoimmune diseases, especially children, according to data published online ahead of print March 31 in JAMA Neurology. Researchers conducted a retrospective population-based study using claims from a nationwide employer-provided health insurance plan in the United States. All 2,518,034 participants included in the study were beneficiaries enrolled between 1999 and 2006. The investigators examined the relationship between epilepsy and type 1 diabetes mellitus, psoriasis, rheumatoid arthritis, Graves disease, Hashimoto thyroiditis, Crohn disease, ulcerative colitis, systemic lupus erythematosus, antiphospholipid syndrome, Sjögren syndrome, myasthenia gravis, and celiac disease. The odds ratio of epilepsy was 3.8 among patients with autoimmune diseases and 5.2 among children. Based on their findings, the authors recommended that patients with epilepsy undergo surveillance for autoimmune disease, and vice versa.

Migraineurs whose stress decreases from one day to the next have a significantly increased risk of migraine onset on the subsequent day, according to a study published online ahead of print March 26 in Neurology. Twenty-two patients with migraine participated in a three-month electronic diary study. Participants entered data daily regarding migraine attack experience, as well as subjective stress ratings. Stress was assessed using the Perceived Stress Scale and the Self-Reported Stress Scale. Level of stress was generally not associated with migraine occurrence. Decline in stress from one evening diary to the next was associated with increased migraine onset during the subsequent six, 12, and 18 hours for the Perceived Stress Scale. Decline in stress was associated with migraine onset after controlling for level of stress for all time points.

Patients older than 60 with stroke resulting from blockage of the middle cerebral artery (MCA) benefit from hemicraniectomy, researchers reported March 20 in the New England Journal of Medicine. Investigators randomly assigned 112 patients age 61 or older with malignant MCA infarction to conservative treatment in the ICU or hemicraniectomy. The primary end point was survival without severe disability (defined as a score of 0 to 4 on the modified Rankin scale). The proportion of patients who survived without severe disability was 38% in the hemicraniectomy group, compared with 18% in the control group. This difference resulted from lower mortality in the surgery group (33% vs 70%). Infections were more frequent in the hemicraniectomy group, and herniation was more frequent in the control group.

The FDA has approved Topamax (topiramate) for the prevention of migraine headaches in adolescents ages 12 to 17. Topamax is the first drug with FDA approval for migraine prevention in this age group. The medication is taken daily to reduce the frequency of migraine headaches. A clinical trial that enrolled 103 participants established the safety and effectiveness of Topamax in preventing migraine headaches in adolescents ages 12 to 17. Participants treated with Topamax had a decrease in migraine frequency of approximately 72%, compared with 44% in participants who took placebo. The most common adverse reactions with the approved dose of Topamax (100 mg) were paresthesia, upper respiratory infection, anorexia, and abdominal pain. Topamax is manufactured by Janssen Pharmaceuticals of Titusville, New Jersey.

The FDA has approved Evzio (naloxone hydrochloride injection), a prescription treatment that family members or caregivers can use to treat a person suspected to have had an opioid overdose. Evzio rapidly delivers a single dose of naloxone through a handheld autoinjector that can be carried in a pocket or stored in a medicine cabinet. Evzio provides intramuscular or subcutaneous administration. Once turned on, the device provides verbal instruction about how to deliver the medication. In one pharmacokinetic study of 30 patients, a single Evzio injection provided equivalent naloxone, compared with a single dose of naloxone injection using a standard syringe. Administering Evzio to patients who are opioid dependent may result in severe opioid withdrawal. Evzio is manufactured by kaléo, which is based in Richmond, Virginia.

The International League Against Epilepsy has altered its practical definition of epilepsy per the recommendation of a task force, according to an article published online ahead of print April 14 in Epilepsia. Recognizing the limitations of the practical definition of epilepsy as two unprovoked seizures more than 24 hours apart, the task force proposed that epilepsy be considered to be a disease of the brain defined by any of the following conditions: (1) At least two unprovoked (or reflex) seizures occurring more than 24 h apart; (2) one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (ie, at least 60%) after two unprovoked seizures, occurring over the next 10 years; (3) diagnosis of an epilepsy syndrome.

Older people who have apathy but not depression may have smaller brain volumes than those without apathy, according to data published online ahead of print April 16 in Neurology. Investigators performed cross-sectional analyses of data from 4,354 persons without dementia (average age, 76) participating in a population-based study. Apathy symptoms were assessed with the Geriatric Depression Scale. Brain volumes and total white matter lesion (WML) volume were estimated on 1.5-T MRI using an automated segmentation program. Regional WML load was calculated using a semiquantitative scale. Compared with individuals with fewer than two apathy symptoms, participants with two or more apathy symptoms had significantly smaller gray matter volumes, smaller white matter volumes, and smaller thalamus volumes. The latter individuals also were more likely to have WMLs in the frontal lobe.

The APOE4 gene variant confers a substantially greater risk for Alzheimer’s disease to women than it does to men, researchers reported online ahead of print April 14 in Annals of Neurology. The group performed Cox proportional hazards analysis to compute hazard ratios (HRs) for an APOE-by-sex interaction on conversion in 5,496 healthy individuals and 2,588 patients with mild cognitive impairment (MCI). The investigators also tested the interaction in CSF biomarker levels of 980 subjects from the Alzheimer’s Disease Neuroimaging Initiative. Among controls, male and female carriers were more likely to convert to MCI or Alzheimer’s disease, but the effect was stronger in women (HR, 1.81 for women; HR, 1.27 for men). The interaction remained significant in a predefined subanalysis that was restricted to APOE3/3 and APOE3/4 genotypes.

The size and shape of the nucleus accumbens and the amygdala may differ in young adults who smoke marijuana at least once a week, according to a study published April 16 in the Journal of Neuroscience. Investigators collected high-resolution MRI scans on young adults who used recreational marijuana and on controls. The researchers conducted three independent analyses of morphometry in gray matter density, volume (total brain and regional volumes), and surface morphometry. The study authors found greater gray matter density in marijuana users than in control participants in the left nucleus accumbens extending to the subcallosal cortex, hypothalamus, sublenticular extended amygdala, and left amygdala, even after controlling for age, sex, alcohol use, and cigarette smoking. Trend-level effects were observed for a volume increase in the left nucleus accumbens only.

Neuronal death in Parkinson’s disease may occur when the immune system mistakes neurons for foreign invaders and kills them, according to a study published April 16 in Nature Communications. An examination of postmortem brain tissue revealed major histocompatibility complex class I (MHC-1) proteins in catecholaminergic substantia nigra and locus coeruleus neurons. When researchers conducted in vitro experiments with mouse neurons and human neurons created from embryonic stem cells, they found that under certain circumstances, including conditions that occur in Parkinson’s disease, the neurons use MHC-1 to display antigens. Among the different types of neurons tested, the two types affected in Parkinson’s disease were far more responsive than other neurons to signals that triggered antigen display. The researchers also confirmed that T cells recognized and attacked neurons displaying specific antigens.

People who have had a stroke who consistently control their blood pressure may reduce the likelihood of a second stroke by more than half, according to research published online ahead of print March 27 in Stroke. In a post hoc analysis, 3,680 individuals with recent stroke who were followed up for two years were grouped according to the proportion of visits during which their blood pressure was controlled (ie, <140/90 mm Hg). Consistency of blood pressure control affected outcomes in individuals with baseline systolic blood pressure greater than 132 mm Hg. Among individuals with baseline systolic blood pressure higher than 153 mm Hg, risks of stroke, myocardial infarction, or vascular death were lower in those with blood pressure controlled during 75% or more visits, versus less than 25% of visits.

Individuals between ages 18 and 24 who occasionally use stimulant drugs may have impaired neuronal activity in the parts of the brain associated with anticipatory functioning, according to research published March 26 in the Journal of Neuroscience. Investigators recruited 158 nondependent occasional stimulant users and 47 stimulant-naive controls. Participants completed a stop signal task while undergoing functional MRI. Compared with controls, occasional stimulant users showed attenuated neural activation related to the magnitude of probabilistic expectations of inhibitory demand in several areas, including the left prefrontal cortex and left caudate. The results indicate that clinicians may be able to use brain activity patterns as a means of identifying at-risk youth long before they have any obvious outward signs of addictive behaviors, according to the investigators.

—Erik Greb

PET is a promising tool for determining which severely brain damaged individuals in vegetative states have the potential to recover consciousness, according to research published online ahead of print April 16 in Lancet. Investigators examined 81 patients in a minimally conscious state, 41 patients with unresponsive wakefulness syndrome, and four patients with locked-in syndrome. The researchers performed repeated standardized clinical assessments with the Coma Recovery Scale–Revised (CRS-R), cerebral 18F-fluorodeoxyglucose (FDG) PET, and fMRI while the patients performed mental activation tasks. Mental imagery fMRI was less sensitive at diagnosing a minimally conscious state than FDG-PET (45% vs 93%) and had less agreement with behavioral CRS-R scores than FDG-PET (63% vs 85%). 18F-FDG PET correctly predicted outcome in 75 of 102 patients, and fMRI in 36 of 65 patients.

The risk of epilepsy may be heightened significantly among patients with autoimmune diseases, especially children, according to data published online ahead of print March 31 in JAMA Neurology. Researchers conducted a retrospective population-based study using claims from a nationwide employer-provided health insurance plan in the United States. All 2,518,034 participants included in the study were beneficiaries enrolled between 1999 and 2006. The investigators examined the relationship between epilepsy and type 1 diabetes mellitus, psoriasis, rheumatoid arthritis, Graves disease, Hashimoto thyroiditis, Crohn disease, ulcerative colitis, systemic lupus erythematosus, antiphospholipid syndrome, Sjögren syndrome, myasthenia gravis, and celiac disease. The odds ratio of epilepsy was 3.8 among patients with autoimmune diseases and 5.2 among children. Based on their findings, the authors recommended that patients with epilepsy undergo surveillance for autoimmune disease, and vice versa.

Migraineurs whose stress decreases from one day to the next have a significantly increased risk of migraine onset on the subsequent day, according to a study published online ahead of print March 26 in Neurology. Twenty-two patients with migraine participated in a three-month electronic diary study. Participants entered data daily regarding migraine attack experience, as well as subjective stress ratings. Stress was assessed using the Perceived Stress Scale and the Self-Reported Stress Scale. Level of stress was generally not associated with migraine occurrence. Decline in stress from one evening diary to the next was associated with increased migraine onset during the subsequent six, 12, and 18 hours for the Perceived Stress Scale. Decline in stress was associated with migraine onset after controlling for level of stress for all time points.

Patients older than 60 with stroke resulting from blockage of the middle cerebral artery (MCA) benefit from hemicraniectomy, researchers reported March 20 in the New England Journal of Medicine. Investigators randomly assigned 112 patients age 61 or older with malignant MCA infarction to conservative treatment in the ICU or hemicraniectomy. The primary end point was survival without severe disability (defined as a score of 0 to 4 on the modified Rankin scale). The proportion of patients who survived without severe disability was 38% in the hemicraniectomy group, compared with 18% in the control group. This difference resulted from lower mortality in the surgery group (33% vs 70%). Infections were more frequent in the hemicraniectomy group, and herniation was more frequent in the control group.

The FDA has approved Topamax (topiramate) for the prevention of migraine headaches in adolescents ages 12 to 17. Topamax is the first drug with FDA approval for migraine prevention in this age group. The medication is taken daily to reduce the frequency of migraine headaches. A clinical trial that enrolled 103 participants established the safety and effectiveness of Topamax in preventing migraine headaches in adolescents ages 12 to 17. Participants treated with Topamax had a decrease in migraine frequency of approximately 72%, compared with 44% in participants who took placebo. The most common adverse reactions with the approved dose of Topamax (100 mg) were paresthesia, upper respiratory infection, anorexia, and abdominal pain. Topamax is manufactured by Janssen Pharmaceuticals of Titusville, New Jersey.

The FDA has approved Evzio (naloxone hydrochloride injection), a prescription treatment that family members or caregivers can use to treat a person suspected to have had an opioid overdose. Evzio rapidly delivers a single dose of naloxone through a handheld autoinjector that can be carried in a pocket or stored in a medicine cabinet. Evzio provides intramuscular or subcutaneous administration. Once turned on, the device provides verbal instruction about how to deliver the medication. In one pharmacokinetic study of 30 patients, a single Evzio injection provided equivalent naloxone, compared with a single dose of naloxone injection using a standard syringe. Administering Evzio to patients who are opioid dependent may result in severe opioid withdrawal. Evzio is manufactured by kaléo, which is based in Richmond, Virginia.

The International League Against Epilepsy has altered its practical definition of epilepsy per the recommendation of a task force, according to an article published online ahead of print April 14 in Epilepsia. Recognizing the limitations of the practical definition of epilepsy as two unprovoked seizures more than 24 hours apart, the task force proposed that epilepsy be considered to be a disease of the brain defined by any of the following conditions: (1) At least two unprovoked (or reflex) seizures occurring more than 24 h apart; (2) one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (ie, at least 60%) after two unprovoked seizures, occurring over the next 10 years; (3) diagnosis of an epilepsy syndrome.

Older people who have apathy but not depression may have smaller brain volumes than those without apathy, according to data published online ahead of print April 16 in Neurology. Investigators performed cross-sectional analyses of data from 4,354 persons without dementia (average age, 76) participating in a population-based study. Apathy symptoms were assessed with the Geriatric Depression Scale. Brain volumes and total white matter lesion (WML) volume were estimated on 1.5-T MRI using an automated segmentation program. Regional WML load was calculated using a semiquantitative scale. Compared with individuals with fewer than two apathy symptoms, participants with two or more apathy symptoms had significantly smaller gray matter volumes, smaller white matter volumes, and smaller thalamus volumes. The latter individuals also were more likely to have WMLs in the frontal lobe.

The APOE4 gene variant confers a substantially greater risk for Alzheimer’s disease to women than it does to men, researchers reported online ahead of print April 14 in Annals of Neurology. The group performed Cox proportional hazards analysis to compute hazard ratios (HRs) for an APOE-by-sex interaction on conversion in 5,496 healthy individuals and 2,588 patients with mild cognitive impairment (MCI). The investigators also tested the interaction in CSF biomarker levels of 980 subjects from the Alzheimer’s Disease Neuroimaging Initiative. Among controls, male and female carriers were more likely to convert to MCI or Alzheimer’s disease, but the effect was stronger in women (HR, 1.81 for women; HR, 1.27 for men). The interaction remained significant in a predefined subanalysis that was restricted to APOE3/3 and APOE3/4 genotypes.

The size and shape of the nucleus accumbens and the amygdala may differ in young adults who smoke marijuana at least once a week, according to a study published April 16 in the Journal of Neuroscience. Investigators collected high-resolution MRI scans on young adults who used recreational marijuana and on controls. The researchers conducted three independent analyses of morphometry in gray matter density, volume (total brain and regional volumes), and surface morphometry. The study authors found greater gray matter density in marijuana users than in control participants in the left nucleus accumbens extending to the subcallosal cortex, hypothalamus, sublenticular extended amygdala, and left amygdala, even after controlling for age, sex, alcohol use, and cigarette smoking. Trend-level effects were observed for a volume increase in the left nucleus accumbens only.

Neuronal death in Parkinson’s disease may occur when the immune system mistakes neurons for foreign invaders and kills them, according to a study published April 16 in Nature Communications. An examination of postmortem brain tissue revealed major histocompatibility complex class I (MHC-1) proteins in catecholaminergic substantia nigra and locus coeruleus neurons. When researchers conducted in vitro experiments with mouse neurons and human neurons created from embryonic stem cells, they found that under certain circumstances, including conditions that occur in Parkinson’s disease, the neurons use MHC-1 to display antigens. Among the different types of neurons tested, the two types affected in Parkinson’s disease were far more responsive than other neurons to signals that triggered antigen display. The researchers also confirmed that T cells recognized and attacked neurons displaying specific antigens.

People who have had a stroke who consistently control their blood pressure may reduce the likelihood of a second stroke by more than half, according to research published online ahead of print March 27 in Stroke. In a post hoc analysis, 3,680 individuals with recent stroke who were followed up for two years were grouped according to the proportion of visits during which their blood pressure was controlled (ie, <140/90 mm Hg). Consistency of blood pressure control affected outcomes in individuals with baseline systolic blood pressure greater than 132 mm Hg. Among individuals with baseline systolic blood pressure higher than 153 mm Hg, risks of stroke, myocardial infarction, or vascular death were lower in those with blood pressure controlled during 75% or more visits, versus less than 25% of visits.

Individuals between ages 18 and 24 who occasionally use stimulant drugs may have impaired neuronal activity in the parts of the brain associated with anticipatory functioning, according to research published March 26 in the Journal of Neuroscience. Investigators recruited 158 nondependent occasional stimulant users and 47 stimulant-naive controls. Participants completed a stop signal task while undergoing functional MRI. Compared with controls, occasional stimulant users showed attenuated neural activation related to the magnitude of probabilistic expectations of inhibitory demand in several areas, including the left prefrontal cortex and left caudate. The results indicate that clinicians may be able to use brain activity patterns as a means of identifying at-risk youth long before they have any obvious outward signs of addictive behaviors, according to the investigators.

—Erik Greb