Kelly Connelly

Male teens who experiment with cannabis before age 16, and have a high genetic risk for schizophrenia, show a different brain development trajectory than low-risk peers who use cannabis.

The discovery, made from a combined analysis of over 1,500 youth, contributes to a growing body of evidence implicating cannabis use in adolescence and schizophrenia later in life, researchers said.

“Given the solid epidemiologic evidence supporting a link between cannabis exposure during adolescence and schizophrenia, we investigated whether the use of cannabis during early adolescence (by 16 years of age) is associated with variations in brain maturation as a function of genetic risk for schizophrenia,” said senior author Dr. Tomas Paus of the University of Toronto's department of psychiatry .

“Our findings suggest that cannabis use might interfere with the maturation of the cerebral cortex in male adolescents at high risk for schizophrenia by virtue of their polygenic risk score. Their brains showed lower cortical thickness compared with low-risk male participants and low-or-high risk female participants who used the drug.”

Professor Paus is the Anne and Max Tanenbaum Professor and Chair in Population Neuroscience at Baycrest, University of Toronto and the Dr. John and Consuela Phelan Scholar at Child Mind Institute, New York. The paper's first author is Leon French, post-doctoral fellow at Baycrest's Rotman Research Institute.

The study was led by Baycrest Health Sciences' Rotman Research Institute in Toronto and was reported in JAMA Psychiatry (online) on August 26, ahead of print publication. (Read the Globe article about the research.)

Adolescence is a period of vulnerability with regard to the emergence of psychotic disorders, especially in boys. Environmental influences on the continuing maturation of neural circuits during adolescence are of great interest to neuroscientists and medical professionals.

Paus, a prominent researcher and pioneer in the field of population neuroscience, strongly cautioned that more research is needed to determine whether lower cortical thickness actually increases the probability of schizophrenia in at-risk males later in life.

“Brain aging is about brain development,” said Paus. “Our study shows the importance of understanding environmental influences on the developing brain in early life as this can have important implications for brain health through the lifespan.”

The research team used observations from three large samples of typically developing youth in Canada and Europe. Researchers examined data from a total of 1,577 participants (aged 12 - 21 years, 57 per cent male / 43 per cent female), that included information on cannabis use, brain imaging results, and polygenic risk score for schizophrenia. The data came from the Saguenay Youth Study in Quebec, the Avon Longitudinal Study of parents and Children in the U.K., and the IMAGEN Study in the U.K., Germany, France and Ireland.

According to the National Alliance on Mental Illness: “It is too early to classify schizophrenia as either a neurodevelopmental (impairment of the growth and development of the brain) or a neurodegenerative (progressive loss of structure or function of neurons) disorder, as both seem to occur over the course of the illness. Research strongly suggests the emergence of schizophrenia is a result of both genetic and environmental factors.”

The study was funded by the Canadian Institutes of Health Research, the Natural Sciences and Engineering Research Council of Canada, the National Institutes of Health (U.S.), European Union and the Anne and Max Tanenbaum Professor and Chair in Population Neuroscience.

Kelly Connelly is a writer with Baycrest Health Sciences.

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Living in the third person: this memory glitch affects healthy, high-functioning people

sgupta — Fri, 24 Apr 2015 11:16:14 +0000

Living in the third person: this memory glitch affects healthy, high-functioning people sgupta Fri, 04/24/2015 - 07:16

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“We are very grateful that these three individuals came forward and allowed us to test them so we could document their syndrome and try to understand the brain mechanisms behind it,” said Professor Brian Levine (photo by _annamo via Flickr)

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“They cannot re-experience the past with a vivid sense of personal reliving. It's as if their past was experienced in the third person,” says researcher

Imagine living a healthy, normal life without the ability to remember personal events from your past. You have heard about them from family and friends, but you can't see or imagine yourself in any of them.

Cognitive scientists from the University of Toronto had a rare opportunity to examine three middle-aged adults (two from the U.S., the other from the U.K.) who live their lives in the "third person" because of a condition known as lifelong severely deficient autobiographical memory (SDAM).

The intriguing findings are posted online in the journal Neuropsychologia, ahead of the print edition.

“Many of us can relate to the idea that people have different abilities when remembering events. What is unique about these individuals is that they have no personal recollection,” said Professor Brian Levine. The senior author on the paper, Levine is a professor in the Faculty of Medicine’s division of neurology and Institute of Medical Science as well as senior scientist at Baycrest Health Sciences’ Rotman Research Institute.

“Even though they can learn and recall information normally and hold down professional careers, they cannot re-experience the past with a vivid sense of personal reliving. It's as if their past was experienced in the third person.”

People with SDAM have no history of amnesia, brain injury, birth complications, seizures, stroke, neurological disease or psychological disorder to explain their memory syndrome. They are highly educated and functioning normally in their occupational and social roles. While scientists are unsure how rare the condition is, the Canadian study represents the first opportunity to examine the memory syndrome in healthy individuals in a lab setting with brain imaging and reliable and valid memory testing protocols.

The research team discovered reduced vividness, visualization and recollection of both personal events and laboratory-presented material in the three adults compared to control subjects. Using different methods of brain imaging – structural and functional magnetic resonance imaging and electroencephalography (EEG) – the team found evidence of brain differences in the SDAM cases compared to control subjects. The researchers also examined the size of the hippocampus, which plays a critical role in memory, and found a subtle volume reduction in the right hippocampus in the SDAM cases.

When presented with events from their own life, the SDAM cases had reduced activation in midline brain regions that play a prominent role in autobiographical memory processes, such as mental time travel. When their memory for pictures was tested, the EEG signals associated with conscious recollection in healthy adults were greatly reduced in the SDAM cases, even though their recognition of the pictures was normal. This suggested that the SDAM cases can learn, but without a normal recollective experience.

“The SDAM cases had very little access to autobiographical details from their remote past, including visualization of those experiences and their emotional state,” said U of T alumna Dr. Daniela Palombo, the study's lead author and currently a post-doctoral researcher at VA Boston Healthcare System and Boston University School of Medicine.

“We also found significant activation reductions in core regions known to play a role in autobiographical memory, which may provide some of the explanation for their inability to mentally project the self through time and their reduced visualization abilities, compared to the matched controls.”

Yet the findings also suggested how it is that the SDAM cases can still function normally in day-to-day life. They rely on intact non-recollective memory, such as rehearsed factual knowledge about themselves or others.

“There is a lot that we can accomplish with these skills, which are also part of normal memory function,” said Levine. The SDAM syndrome may involve a lifetime of compensation using these abilities.

Palombo cautioned that further studies are required to tease out other possible neurological factors and health issues that may play a role in SDAM.

SDAM is the extreme opposite of another syndrome known as highly superior autobiographical memory (HSAM), which refers to individuals with the uncanny ability to recall a vast amount of episodic autobiographical memory details.

Kelly Connelly is senior media officer at Baycrest Health Sciences’ Rotman Research Institute, a partner of the University of Toronto.

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Anxiety can damage brain and accelerate Alzheimer's, researchers say

sgupta — Wed, 12 Nov 2014 08:51:39 +0000

Anxiety can damage brain and accelerate Alzheimer's, researchers say sgupta Wed, 11/12/2014 - 03:51

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Assistant Professor Linda Mah

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"Clinicians should routinely screen for anxiety in people who have memory problems because anxiety signals that these people are at greater risk for developing Alzheimer’s," says Linda Mah

People with mild cognitive impairment (MCI) are at increased risk of converting to Alzheimer’s disease within a few years, but a new study warns the risk increases significantly if they suffer from anxiety.

The study, led by researchers at the University of Toronto and Baycrest Health Sciences’ Rotman Research Institute, has shown clearly for the first time that anxiety symptoms in individuals diagnosed with MCI increase the risk of a speedier decline in cognitive functions – independent of depression (another risk marker). For MCI patients with mild, moderate or severe anxiety, Alzheimer’s risk increased by 33 per cent, 78 per cent and 135 per cent respectively.

The research team also found that MCI patients who had reported anxiety symptoms at any time over the follow-up period had greater rates of atrophy in the medial temporal lobe regions of the brain, which are essential for creating memories and which are implicated in Alzheimer’s.

Until now, anxiety as a potentially significant risk marker for Alzheimer’s in people diagnosed with MCI has never been isolated for a longitudinal study to gain a clearer picture of just how damaging anxiety symptoms can be on cognition and brain structure over a period of time. A growing body of literature has identified late-life depression as a significant risk marker for Alzheimer’s. Anxiety has historically been subsumed under the rubric of depression in psychiatry. Depression is routinely screened for in assessment and follow-up of memory clinic patients; anxiety is not routinely assessed.

“Our findings suggest that clinicians should routinely screen for anxiety in people who have memory problems because anxiety signals that these people are at greater risk for developing Alzheimer’s,” said Linda Mah. The principal investigator on the study, Mah is an assistant professor in U of T’s department of psychiatry and clinician-scientist with Baycrest’s Rotman Research Institute.

Dr. Mah is also a co-investigator in a multi-site study lead by the Centre for Addiction and Mental Health, and partially funded by federal dollars (Brain Canada), to prevent Alzheimer’s in people with late-life depression or MCI who are at high risk for developing the progressive brain disease.

“While there is no published evidence to demonstrate whether drug treatments used in psychiatry for treating anxiety would be helpful in managing anxiety symptoms in people with mild cognitive impairment or in reducing their risk of conversion to Alzheimer’s, we think that at the very least behavioural stress management programs could be recommended,” said Professor Mah. “In particular, there has been research on the use of mindfulness-based stress reduction in treating anxiety and other psychiatric symptoms in Alzheimer’s and this is showing promise.”

The study used data from the large, population-based Alzheimer’s Disease Neuroimaging Initiative to analyze anxiety, depression, cognitive and brain structural changes in 376 adults, aged 55 – 91, over a three-year period. Those changes were monitored every six months. All of the adults had a clinical diagnosis of amnestic MCI and a low score on the depression rating scale, indicating that anxiety symptoms were not part of clinical depression.

MCI is considered a risk marker for converting to Alzheimer’s disease within a few years. It is estimated that half-a-million Canadians aged 65-and-older have MCI, although many go undiagnosed. Not all MCI sufferers will convert to Alzheimer’s – some will stabilize and others may even improve in their cognitive powers.

The study has yielded important evidence that anxiety is a “predictive factor” of whether an individual with MCI will convert to Alzheimer’s or not, said Mah. Studies have shown that anxiety in MCI is associated with abnormal concentrations of plasma amyloid protein levels and T-tau proteins in cerebrospinal fluid, which are biomarkers of Alzheimer’s. Depression and chronic stress have also been linked to smaller hippocampal volume and increased risk of dementia.

In addition to Mah, the research team included Dr. Malcolm Binns, assistant professor of the Dalla Lana School of Public Health at U of T and a statistician scientist at Baycrest’s Rotman Research Institute, and Dr. David Steffens (department of psychiatry, University of Connecticut Health Centre).

The American Journal of Geriatric Psychiatry reported the findings online on October 29, ahead of print publication scheduled for May 2015.

The study was supported by the National Institutes of Health and the Geoffrey H. Wood Foundation.

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Unable to remember a single face -- unless it’s Paris Hilton!

sgupta — Thu, 10 Nov 2011 10:39:03 +0000

Unable to remember a single face -- unless it’s Paris Hilton! sgupta Thu, 11/10/2011 - 05:39

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Paris Hilton is memorable. (Photo from Bigstock)

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Study shows intact memory for familiar information, despite memory deficit

A 22-year-old woman who has had amnesia since birth has demonstrated she can’t hold a single face or word in short-term memory – unless the information is familiar to her.

When presented with a face such as Hollywood celebrity Paris Hilton and asked to recognize the face a few seconds later, the woman, known as HC, could remember the A-list party girl. However, she was unable to remember novel, unfamiliar faces as well as healthy age, education and IQ- matched control participants. HC’s short-term memory was even impaired for faces that were famous, but whom HC did not know, such as former U.S. first lady Hillary Clinton.

The single case study with the woman was led by Baycrest’s Rotman Research Institute, in collaboration with the University of Toronto. The study is posted online in the science journal Neuropsychologia, in advance of print publication.

The finding is important for understanding the nuanced workings of short-term memory in people with a devastating memory disorder such as amnesia. The study provides the first strong evidence that the short-term memory deficit in individuals with amnesia is most apparent only when the individual is trying to recall new information that is “unfamiliar” to them. When information is already “familiar” from past repetitive exposure, it is more likely to be retained in short-term memory, also known as “working memory.”

Despite HC’s severe memory impairment – the result of experiencing hypoxia (loss of oxygen) in the first week of life – she is a relatively normal functioning individual and college graduate, who is an avid film buff and celebrity watcher.

“This woman is missing 50 percent of the normal volume of her hippocampus with no obvious damage to other parts of her brain. This provides an extraordinary opportunity to generate new insights about how this crucial memory centre of the brain affects both short-term and long-term memory,” said lead investigator Nathan Rose, a post-doctoral fellow in Cognitive Neuroscience at Baycrest’s Rotman Research Institute. Rose conducted the study with Fergus Craik, a University of Toronto emeritus professor, and York University professor Shayna Rosenbaum.

“We wanted to test if HC’s short-term memory was impaired, and, if so, whether this impairment only existed for novel stimuli. That is exactly what we found.”

Amnestic individuals have profound deficits in long term memory and yet many seem to function fine by relying on their short-term memory which has traditionally been thought to be intact. However, a growing body of scientific evidence, including this latest study, is showing that “working memory” is also impaired in this population.

“Our findings add to the growing evidence that short-term memory is not intact in amnesia. However, to my knowledge, we are the first to directly test the hypothesis that short-term memory functions better if the information has some past familiarity to the person,” said Craik, a collaborator on the study and co-editor of the Oxford Handbook of Memory.

The findings may explain why individuals with amnesia are often able to compensate for their profound memory deficit in social settings by seeking out familiar cues to support short-term memory.

Single cases with a clear pattern of specific brain deficits, such as HC, are incredibly rare and important for neuroscience. These cases enable researchers to generate more precise data that demonstrates a specific brain area is necessary for certain memory functions. Most individuals with amnesia typically present with diffuse damage in the brain which can complicate brain imaging and behavioural data interpretation.

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Music-based cartoons can help children

sgupta — Wed, 05 Oct 2011 09:54:46 +0000

Music-based cartoons can help children sgupta Wed, 10/05/2011 - 05:54

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Music-based cognitive training cartoons are useful in improving children's language skills.

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90 per cent of children in study showed cognitive benefit

Canadian scientists who specialize in learning, memory and language in children have found exciting evidence that pre-schoolers can improve their verbal intelligence after only 20 days of classroom instruction using interactive, music-based cognitive training cartoons.

The study – conducted at York University by Sylvain Moreno, a U of T psychology professor who is with Baycrest’s Rotman Research Institute (RRI) – is posted online in Psychological Science (a journal of the Association for Psychological Science), in advance of print publication in the October issue of the journal.

The cognitive benefit was striking and consistent in 90% of the children who took the four-week learning program and was additionally confirmed by brain imaging data that indicated brain changes had taken place related to the training.

“Our data have confirmed a rapid transfer of cognitive benefits in young children after only 20 days of training on an interactive, music-based cognitive training program. The strength of this effect in almost all of the children was remarkable,” said Moreno, a world expert on neuroeducation. He is the lead scientist at Baycrest’s Centre for Brain Fitness.

The findings have exciting implications for conceptualizing and improving neuroeducation programs for children of all ages, and potentially for older adults.

The scientific team included other prominent researchers in the field of cognitive development – Dr. Ellen Bialystok, York University, and principal collaborator in the study; Professor Tom Chau of Bloorview Research Institute and the University of Toronto; and Professor Glenn Schellenberg, University of Toronto Mississauga. Artist-educators from The Royal Conservatory’s Learning Through the Arts program conducted the experimental training with pre-schoolers, and George Brown College provided assistance in the earliest stages of software development for the training programs.

“These results are dramatic not only because they clearly connect cognitive improvement to musical training, but also because the improvements in language and attention are found in completely different domains than the one used for training. This has enormous implications for development and education,” said Bialystok, Distinguished Research Professor of Psychology at York University and associate scientist at Baycrest’s Rotman Research Institute.

In the study, 48 pre-schoolers four to six years of age participated in computer-based, cognitive training programs that were projected on a large classroom wall and featured colourful, animated cartoon characters delivering the lessons. The children were divided into two groups. One group received music-based cognitive training that involved a combination of motor, perceptual and cognitive tasks, and included training on rhythm, pitch, melody, voice and basic musical concepts. The other group received visual art training that emphasized the development of visuo-spatial skills relating to concepts such as shape, color, line, dimension and perspective.

Each group received two training sessions of one-hour duration each day in classroom, over four weeks, led by instructors at The Royal Conservatory in Toronto.

Researchers tested the children for verbal and spatial intelligence before and after the training using the Wechsler Preschool and Primary Scale of Intelligence (Third Edition). The team also conducted brain imaging using non-invasive electroencephalography (EEG) which measures the time course of brain activity.

The verbal IQ tests assessed the children’s attention, word recall and ability to analyze information and solve problems using language-based reasoning. Brain imaging enabled researchers to detect if functional brain changes had occurred related to the cognitive training. When the children were re-tested five to 20 days after the end of the training programs, researchers did not find any significant increase in verbal intelligence or brain changes for the children who participated in the visual art training module. However, they found quite a different result in the children who took the music-based, cognitive training. Ninety percent of those children exhibited intelligence improvements – five times larger than the other group – on a measure of vocabulary knowledge, as well as increased accuracy and reaction time. The music group also showed brain changes that co-related to their enhanced cognitive performance.

“The results of this study strongly affirm the resonance between music and child development, and encourage us to think of music not just as a medium or tool through which treatment might be delivered, but as the treatment itself,” said Chau, a senior scientist at Bloorview Research Institute and Canada Research Chair in Paediatric Rehabilitation Engineering.

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Financial Economics

sgupta — Wed, 21 Sep 2011 16:28:13 +0000

Financial Economics sgupta Wed, 09/21/2011 - 12:28

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Guitar player (Photo by Big Stock)

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Older musicians experience less age-related decline in hearing abilities than non-musicians

A study led by a U of T PhD candidate in psychology has found the first evidence that lifelong musicians experience less age-related hearing problems than non-musicians.

While hearing studies have already shown that trained musicians have highly developed auditory abilities compared to non-musicians, this is the first study to examine hearing abilities in musicians and non-musicians across the age spectrum – from 18 to 91 years of age. The study is published online in the journal Psychology and Aging, ahead of print publication.

Investigators wanted to determine if lifelong musicianship protects against normal hearing decline in later years, specifically for central auditory processing associated with understanding speech. Hearing problems are prevalent in the elderly, who often report having difficulty understanding speech in the presence of background noise. Scientists describe this as the “cocktail party problem”. Part of this difficulty is due to an age-related decrease in the ability to detect and discriminate acoustic information from the environment.

“What we found was that being a musician may contribute to better hearing in old age by delaying some of the age-related changes in central auditory processing. This advantage widened considerably for musicians as they got older when compared to similar-aged non-musicians,” said lead investigator Benjamin Rich Zendel a PhD candidate at U of T who conducted the study with Dr. Claude Alain, senior cognitive scientist and assistant director of the Rotman Research Institute.

In the study, 74 musicians (ages 19-91) and 89 non-musicians (ages 18-86) participated in a series of auditory assessments. A musician was defined as someone who started musical training by the age of 16, continued practicing music until the day of testing, and had an equivalent of at least six years of formal music lessons. Non-musicians in the study did not play any musical instrument.

Wearing insert earphones, participants sat in a soundproof room and completed four auditory tasks that assessed pure tone thresholds (ability to detect sounds that grew increasingly quieter); gap detection (ability to detect a short silent gap in an otherwise continuous sound, which is important for perceiving common speech sounds such as the words that contain “aga” or ata”); mistuned harmonic detection (ability to detect the relationship between different sound frequencies, which is important for separating sounds that are occurring simultaneously in a noisy environment); and speech-in-noise (ability to hear a spoken sentence in the presence of background noise).

Scientists found that being a musician did not offer any advantage in the pure-tone thresholds test, across the age span. However, in the three other auditory tasks – mistuned harmonic detection, gap detection and speech-in-noise – musicians showed a clear advantage over non-musicians and this advantage gap widened as both groups got older. By age 70, the average musician was able to understand speech in a noisy environment as well as an average 50 year old non-musician, suggesting that lifelong musicianship can delay this age-related decline by 20 years.

Most importantly, the three assessments where musicians demonstrated an advantage all rely on auditory processing in the brain, while pure-tone thresholds do not. This suggests that lifelong musicianship mitigates age-related changes in the brains of musicians, which is probably due to musicians using their auditory systems at a high level on a regular basis. In other words, “use it or lose it”.

Zendel, who recently accepted a new position at the BRAMS lab at the Université de Montréal, expects to have a followup study published within the next year that examines differences in brain function of older and younger musicians and non-musicians.

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