Tag: cognitive deficit

Categories : Neurology Substance UseTags :

Meth and PCP Cognitive Deficits Stem from a Common Neurotransmitter Switch

On By ModernMedia
Photo by Inzmam Khan

The effects of sustained drug abuse can manifest in many ways. Loss of memory and reduced cognitive functions are some of the effects that can persist for years. Neurobiologists at the University of California San Diego have now identified a mechanism in the brain that generates drug-induced cognitive impairments.

The researchers investigated how methamphetamine and phencyclidine (PCP or “angel dust”), which take effect by activating different targets in the brain, induce a similar reduction in cognitive ability. How could the same difficulties in memory emerge in response to drugs that trigger different actions in the brain?

The results of this investigation, led by Assistant Project Scientist Marta Pratelli in Professor Nicholas Spitzer’s laboratory, appear in Nature Communications. They showed that meth and PCP caused neurons to change the way they communicate through a process known as neurotransmitter switching.

Neurotransmitter switching is a form of brain plasticity, an evolving area of research investigating how the brain changes function and structure in response to experience. In recent years, Spitzer and his colleagues have also identified roles for neurotransmitter switching in autism spectrum disorder, post-traumatic stress disorder and in exercise.

Examining the cerebral cortex of mice, the investigators found that meth and PCP each caused a switch from the excitatory neurotransmitter glutamate to the inhibitory neurotransmitter GABA (gamma-aminobutyric acid) in the same neurons in the prelimbic region, an area of the frontal cortex involved in executive functions. This switch was linked to a decrease in memory task performance since drug-treated mice performed well in the tasks when the expression of GABA was blocked.

Further experiments showed that even after repeated exposure to the drugs, the researchers were able to reverse this neurotransmitter switch using molecular tools to locally decrease the brain’s electrical activity or using clozapine, an antipsychotic drug. Each of these treatments reversed the memory loss, restoring the performance of mice in the cognitive tasks.

“These results suggest that targeted manipulation of neuronal activity may be used to ameliorate some of the negative effects of repeated drug abuse,” said Pratelli.  

In this new study, the researchers found that a drug-induced increase in the release of dopamine, a neurotransmitter involved in reward, and an increase in the electrical activity of neurons in the cerebral cortex, were required to produce the neurotransmitter switch.

“This study reveals a shared and reversible mechanism that regulates the appearance of cognitive deficits upon exposure to different drugs,” said Spitzer.

The researchers note in their paper that a deeper understanding of brain mechanisms tied to loss of memory from drug use could boost prospects for new treatments, not only resulting in therapy for meth and PCP consumption, but for other disorders as well.

Source: University of San Diego California

Categories : Implants and Prostheses NeurologyTags :

New Neural Prosthetic Device Can Help Restore Memory in Humans

On By ModernMedia
Source: CC0

Scientists have demonstrated the first successful use of a neural prosthetic device to recall specific memories. The findings appear online in Frontiers in Computational Neuroscience.

This groundbreaking research was derived from a 2018 study led by Robert Hampson, PhD, professor of regenerative medicine, translational neuroscience and neurology at Wake Forest University School of Medicine. That study demonstrated the successful implementation of a prosthetic system that uses a person’s own memory patterns to facilitate the brain’s ability to encode and recall memory, improving recall by as much as 37%.

In the previous study, the team’s electronic prosthetic system was based on a multi-input multi-output (MIMO) nonlinear mathematical model, and the researchers influenced the firing patterns of multiple neurons in the hippocampus, a part of the brain involved in making new memories.

In this study, researchers from Wake Forest and University of Southern California (USC) built a new model of processes that assists the hippocampus in helping people remember specific information.

When the brain tries to store or recall information such as, “I turned off the stove” or “Where did I put my car keys?” groups of cells work together in neural ensembles that activate so that the information is stored or recalled.

Using recordings of the activity of these brain cells, the researchers created a memory decoding model (MDM) which let them decode what neural activity is used to store different pieces of specific information.

The neural activity decoded by the MDM was then used to create a pattern, or code, which was used to apply neurostimulation to the hippocampus when the brain was trying to store that information.

“Here, we not only highlight an innovative technique for neurostimulation to enhance memory, but we also demonstrate that stimulating memory isn’t just limited to a general approach but can also be applied to specific information that is critical to a person,” said Brent Roeder, Ph.D., a research fellow in the department of translational neuroscience at Wake Forest University School of Medicine and the study’s corresponding author.

The team enrolled 14 adults with epilepsy who were participating in a diagnostic brain-mapping procedure that used surgically implanted electrodes placed in various parts of the brain to pinpoint the origin of their seizures.

Participants underwent all surgical procedures, post-operative monitoring and neurocognitive testing at one of the three sites participating in this study including Atrium Health Wake Forest Baptist Medical Center, Keck Hospital of USC in Los Angeles and Rancho Los Amigo National Rehabilitation Center in Downey, California.

The team delivered MDM electrical stimulation during visual recognition memory tasks to see if the stimulation could help people remember images better.

They found that when they used this electrical stimulation, there were significant changes in how well people remembered things. In about 22% of cases, there was a noticeable difference in performance.

When they looked specifically at participants with impaired memory function, who were given the stimulation on both sides of their brain, almost 40% of them showed significant changes in memory performance.

“Our goal is to create an intervention that can restore memory function that’s lost because of Alzheimer’s disease, stroke or head injury,” Roeder said.

“We found the most pronounced change occurred in people who had impaired memory.”

Roeder said he hopes the technology can be refined to help people live independently by helping them recall critical information such as whether medication has been taken or whether a door is locked.

“While much more research is needed, we know that MDM-based stimulation has the potential to be used to significantly modify memory,” Roeder said.

Source: Atrium Health Wake Forest Baptist

Categories : Neurology Obstetrics & GynaecologyTags :

Polycystic Ovary Syndrome Tied to Cognitive Problems

On By ModernMedia
Photo by Sora Shimazaki on Pexels

Those with polycystic ovary syndrome (PCOS) may be more likely to have memory and thinking problems in middle age, according to a study involving over 900 women, 66 of whom had PCOS. The study, published in Neurology, followed the women for 30 years.

PCOS is a hormonal disorder that is defined by irregular menstruation and elevated levels of androgen. Other symptoms may include excess hair growth, acne, infertility and poor metabolic health.

“Polycystic ovary syndrome is a common reproductive disorder that impacts up to 10% of women,” said study author Heather G. Huddleston, MD, of the University of California, San Francisco.

“While it has been linked to metabolic diseases like obesity and diabetes that can lead to heart problems, less is known about how this condition affects brain health. Our results suggest that people with this condition have lower memory and thinking skills and subtle brain changes at midlife. This could impact a person on many levels, including quality of life, career success and financial security.”

The study involved 907 female participants who were 18 to 30 years old at the start of the study.

They were followed for 30 years, at which time they completed tests to measure memory, verbal abilities, processing speed and attention. At the time of testing, 66 participants had polycystic ovary syndrome.

In a test measuring attention, participants looked at a list of words in different colours and were asked to state the colour of the ink rather than read the actual word. For example, the word “blue” could be displayed in red, so the correct response would be red.

Researchers found for this test, people with PCOS had an average score that was approximately 11% lower compared to people without the condition.

After adjusting for age, race and education, researchers found that people with polycystic ovary syndrome had lower scores on three of the five tests that were given, specifically in areas of memory, attention and verbal abilities, when compared to those without this condition.

At years 25 and 30 of the study, a smaller group of 291 participants had brain scans.

Of those, 25 had PCOS. With the scans, researchers looked at the integrity of the white matter pathways in the brain by looking at movement of water molecules in the brain tissue.

Researchers found that people with PCOS had lower white matter integrity, which may indicate early evidence of brain aging.

“Additional research is needed to confirm these findings and to determine how this change occurs, including looking at changes that people can make to reduce their chances of thinking and memory problems,” Huddleston said.

“Making changes like incorporating more cardiovascular exercise and improving mental health may serve to also improve brain aging for this population.”

A limitation of the study was that PCOS diagnosis was not made by a doctor but was based on androgen levels and self-reported symptoms, so participants may not have remembered all the information accurately.

The study was funded by the University of California, San Francisco.

Source: American Academy of Neurology 

Categories : Environmental EffectsTags :

Lead Exposure Lowered IQ of Americans Born Up to 1996

On By ModernMedia
Old petrol pump
Photo by Ashlee Attebery on Unsplash

A new study calculates that exposure to car exhaust from leaded gas during childhood lowered the IQ levels of about half the population of Americans alive today.

The findings suggest that Americans born before 1996 may now be at greater risk for lead-related health problems, such as faster ageing of the brain. Leaded petrol was banned in the US in 1996, but anyone born in the US before the end of that era, and especially those at the peak of its use in the 1960s and 1970s, had worryingly high lead exposures as children, the researchers said. In South Africa, leaded petrol was only banned at the end of 2005.

The study’s findings were published in Proceedings of the National Academy of Sciences.

Lead is a neurotoxin that can enter the bloodstream via a number of routes and there is no safe level of exposure at any point in life. Young children are especially vulnerable to lead’s ability to impair brain development and lower cognitive ability.

“Lead is able to reach the bloodstream once it’s inhaled as dust, or ingested, or consumed in water,” said study co-author Aaron Reuben, a PhD candidate in clinical psychology. “In the bloodstream, it’s able to pass into the brain through the blood-brain barrier, which is quite good at keeping a lot of toxicants and pathogens out of the brain, but not all of them.”

To answer the complex question of how more than 70 years of leaded petrol use may have left a permanent mark on human health, Reuben and co-authors Michael McFarland and Mathew Hauer, both professors of sociology at Florida State University, opted for a fairly simple strategy.

Using publicly available data on US childhood blood-lead levels, leaded-gas use, and population statistics, they determined the likely lifelong burden of lead exposure carried by every American alive in 2015. From this data, they estimated lead’s assault on our intelligence by calculating IQ points lost from leaded gas exposure as a proxy for its harmful impact on public health – a result which stunned the researchers.

“I frankly was shocked,” Prof McFarland said. “And when I look at the numbers, I’m still shocked even though I’m prepared for it.”

As of 2015, more than 170 million Americans (more than half of the U.S. population) had clinically concerning levels of lead in their blood as children, likely resulting in lower IQs and putting them at higher risk for other long-term health impairments, such as reduced brain size, greater likelihood of mental illness, and increased cardiovascular disease in adulthood.

Leaded gasoline consumption rose rapidly in the early 1960s and peaked in the 1970s. As a result, Reuben and his colleagues found that essentially everyone born during those two decades are all but guaranteed to have been exposed to pernicious levels of lead from car exhaust.

Even more startling was lead’s toll on intelligence: childhood lead exposure may have blunted America’s cumulative IQ score by an estimated 824 million points – nearly three points per person on average. The researchers calculated that at its worst, people born in the mid-to-late 1960s may have lost up to six IQ points, and children registering the highest levels of lead in their blood, eight times the current minimum level to initiate clinical concern, fared even worse, potentially losing more than seven IQ points on average.

While the loss of a few IQ points may seem negligible, the authors note that these changes are dramatic enough to potentially shift people with below-average cognitive ability (IQ score less than 85) to being classified as having an intellectual disability (IQ score below 70).

Prof McFarland is continuing by analysing the racial disparities of childhood lead exposure, hoping to highlight the health inequities suffered by Black children, who were exposed more often to lead and in greater quantities than white children.

Reuben’s next step will be to examine the long-term consequences of past lead exposure on brain health in old age, based on evidence showing that adults with high childhood lead exposure may experience accelerated brain aging.

“Millions of us are walking around with a history of lead exposure,” Reuben said. “It’s not like you got into a car accident and had a rotator cuff tear that heals and then you’re fine. It appears to be an insult carried in the body in different ways that we’re still trying to understand but that can have implications for life.”

Source: Duke University