Daily Archives: 3 March 2024

Research uncovers the most compelling proof yet of the brain’s capacity to offset cognitive deterioration linked to ageing

Researchers have uncovered the most compelling evidence to date that the human brain can adapt to counteract the effects of ageing on cognitive functions. This adaptation involves activating additional brain regions to support and sustain mental performance.

As individuals age, the brain undergoes a natural process of atrophy, characterized by the loss of nerve cells and connections. This process can result in diminished brain functionality. The variability in cognitive resilience among older adults and strategies for safeguarding against cognitive decline remains a subject of scientific inquiry.

The prevailing theory suggests that some individuals’ brains can effectively offset the loss of brain tissue by activating alternative brain regions to aid in task execution. Previous brain imaging studies have indeed observed such compensatory activations, but the impact of these activations on task performance and their contribution to task understanding were unclear.

A groundbreaking study published in the journal eLife, led by researchers from the University of Cambridge in partnership with the University of Sussex, demonstrates that this brain adaptation occurs and enhances task performance in older adults.

Dr Kamen Tsvetanov, spearheading the study at the University of Cambridge, highlights the investigation into the preservation of ‘fluid intelligence’—the capacity for abstract problem-solving—which tends to decline with age. The study aimed to understand why some individuals maintain higher levels of fluid intelligence by possibly engaging different brain regions to counteract detrimental brain changes.

The research utilized functional magnetic resonance imaging (fMRI) to study brain activity in 223 adults aged 19 to 87 from the Cambridge Centre for Ageing & Neuroscience (Cam-CAN). Participants solved puzzles of varying difficulty while undergoing fMRI, allowing the team to analyze changes in brain blood flow and activity patterns.

Findings indicated a general decline in problem-solving ability with age, with specific brain regions, including those involved in visual processing, remaining active. Further machine learning analysis identified two brain areas—the cuneus and a frontal cortex region—showing heightened activity in older individuals, correlating with improved task performance. Notably, the cuneus region’s activity was more closely linked to performance improvements in older participants, providing new insights beyond the multiple demand network’s role.

The role of the cuneus, typically associated with focus and visual processing, suggests a compensatory mechanism for the age-related decline in visual memory, possibly through altered visual attention strategies.

Dr Ethan Knights from the Medical Research Council Cognition and Brain Sciences Unit at Cambridge expresses optimism that understanding this compensatory mechanism could lead to identifying factors that enable some older individuals to maintain cognitive functions better than others. This understanding could inform interventions to extend such benefits to a broader population.

Dr Alexa Morcom from the University of Sussex adds that these findings challenge the previous assumption that compensation relies solely on the multiple-demand network, indicating that preserved brain regions are also crucial in ageing.

Supported by several prestigious institutions, including the Medical Research Council and the Alzheimer’s Society, this research marks a significant advancement in understanding brain plasticity and cognitive ageing, opening avenues for enhancing cognitive health in later life.

More information: Ethan Knights et al, Neural Evidence of Functional Compensation for Fluid Intelligence Decline in Healthy Ageing, eLife. DOI: 10.7554/eLife.93327

Journal information: eLife Provided by University of Cambridge

Older adults with a history of stroke are at a heightened risk of experiencing depression induced by the pandemic

Leave a Reply

A recent longitudinal study conducted by the University of Toronto has shed light on the significant mental health impact that the COVID-19 pandemic has had on older adults with a previous stroke history.

The research involved analyzing data from over 500 older adults with stroke histories sourced from the Canadian Longitudinal Study on Aging. This comprehensive dataset tracks the health of older Canadians. The findings revealed a pronounced increase in depression rates among this demographic throughout the pandemic.

Andie MacNeil, the study’s lead author and a research assistant at the University of Toronto’s Factor-Inwentash Faculty of Social Work, highlighted the heightened vulnerability of stroke survivors to adverse mental health conditions such as depression. The pandemic exacerbated these vulnerabilities due to widespread disruptions in care for stroke patients, significantly affecting their physical and psychological health.

The study distinguished between participants who had previously experienced depression and those who had not before the pandemic. It found that 1 in 7 older adults with a stroke history reported experiencing depression for the first time during the pandemic. Among those with a prior depression history, the rate was even more alarming, with half of these individuals facing a recurrence or continuous depression throughout the pandemic period.

Grace Li, a co-author of the study and a PhD candidate at the University of Victoria, emphasized the struggles faced by stroke survivors during lockdowns, including those previously in good mental health. The study underscores the importance of screening for depression in older adults with a stroke history, including those without a prior history of the condition.

The research also identified risk factors for both the initial onset and recurrence of depression. Functional impairment was a significant risk factor among those with a history of depression, doubling the risk during the pandemic.

Aneisha Taunque, another co-author and research assistant at the University of Toronto, pointed out the specific high risk of depression among older adults with both a stroke and depression history. She noted the crucial role of functional status in this dynamic, exacerbated by the pandemic’s impact on rehabilitation services.

Difficulty in accessing healthcare services emerged as a critical factor, increasing the risk of new-onset depression threefold. Ishnaa Gulati, a Master of Public Health Student and co-author, highlighted the additional stressors for stroke patients, including delays in medical appointments and treatments and the stress of navigating healthcare access challenges.

The study also found that feelings of loneliness at the pandemic’s start significantly increased the risk of developing depression, especially among those who strictly adhered to physical distancing to mitigate COVID-19 risks. Esme Fuller-Thomson, the senior author and a professor at the University of Toronto, emphasized the established link between loneliness and depression risk.

Interestingly, among participants without a depression history, being an immigrant was associated with a roughly threefold increase in the risk of developing depression, likely due to the disproportionate impact of COVID-19 on communities with high immigrant populations.

Family stressors, including separation from family and caregiving challenges, were also identified as risk factors for both new and recurrent depression. Margaret de Groh, a Scientific Manager at the Public Health Agency of Canada, noted the increased depression risk due to pandemic-related family separations and caregiving difficulties.

A sensitivity analysis comparing pre-pandemic data further confirmed the pandemic’s unique impact on depression rates among older adults with a stroke history, underscoring the increased vulnerability of this group during the COVID-19 crisis.

The study’s findings are crucial for healthcare professionals, highlighting key risk factors for depression among stroke survivors. Fuller-Thomson expressed hope that these insights would guide targeted screening and interventions to support the mental health of this particularly vulnerable population.

More information: Andie MacNeil et al, Depression during the COVID-19 pandemic among older adults with stroke history: Findings from the Canadian Longitudinal Study on Aging, International Journal of Geriatric Psychiatry. DOI: 10.1002/gps.6062

Journal information: International Journal of Geriatric Psychiatry Provided by University of Toronto

Higher levels of thyroid hormone linked to increased risk of cognitive disorders in older adults

Leave a Reply

A recent study conducted by Johns Hopkins Medicine has established a correlation between elevated levels of thyroid hormone, known as thyrotoxicosis, and a heightened risk of cognitive disorders in older adults. The study delineates two sources of thyrotoxicosis: exogenous, resulting from the intake of thyroid medication, and endogenous, stemming from thyroid ailments such as hyperthyroidism and Graves’ disease, both of which have been identified as contributing factors to an increased likelihood of cognitive impairment. This research was made available online on October 23 by JAMA Internal Medicine.

Roy Adams, PhD, M.S., the study’s lead author and an assistant professor of psychiatry and behavioural sciences at the Johns Hopkins University School of Medicine, pointed out that while previous research hinted at a possible link between thyrotoxicosis and cognitive disorders, the findings were inconsistent, and studies often excluded cases of exogenous thyrotoxicosis. He highlighted the significance of understanding the impact of thyroid hormone levels on cognitive health, especially given that thyroid hormone prescriptions are among the most common in the United States. A prior investigation by Johns Hopkins Medicine revealed that as many as 20% of individuals taking thyroid hormone medication might be receiving doses too high, exposing them to the risk of exogenous thyrotoxicosis.

The aim of the study, as Adams explained, was to explore whether the aggressive treatment approaches that lead to exogenous thyrotoxicosis could also be causing cognitive damage. The importance of recognizing the adverse effects of overtreatment lies in guiding medical professionals in their prescription of thyroid hormone therapies more cautiously.

For their research, the team utilized a database of electronic health records from Johns Hopkins Medicine, selecting a cohort of 65,931 individuals aged 65 and above who had been under primary care within the Johns Hopkins Health System from January 1, 2014, to May 6, 2023. The initial primary care visit recorded for these participants showed an average age of 71, with each individual having attended at least two appointments spaced by a minimum of 30 days.

The findings revealed a 39% increase in the diagnosis of cognitive disorders among patients experiencing any form of thyrotoxicosis—whether endogenous or exogenous—across different age brackets. Specifically, by the age of 75, 11% of patients who had undergone thyrotoxicosis received a diagnosis of cognitive disorder, compared to 6.4% who hadn’t experienced thyrotoxicosis. This risk escalated with age; by 85, the figures rose to 34% for those with thyrotoxicosis versus 26% for those without. Even after adjusting for potential biases and alternative explanations through statistical models, the increased risk linked to thyrotoxicosis persisted.

Moreover, the study established a correlation between the severity of thyroid hormone excess and the risk of developing cognitive disorders. Patients with severe excess were found to have a 65% increased risk, whereas those with a moderate excess faced a 23% increased risk.

Jennifer Mammen, M.D., Ph.D., the senior author of the study and an assistant professor of medicine at the Johns Hopkins University School of Medicine, underscored the implication of their findings: an increased risk of cognitive disorders could be a consequence of excess thyroid hormone, a frequent outcome of thyroid hormone treatment. She advised clinicians to employ age-appropriate treatment strategies to mitigate the risk of cognitive disorders in older adults by preventing overtreatment.

More information: Roy Adams et al, Endogenous and Exogenous Thyrotoxicosis and Risk of Incident Cognitive Disorders in Older Adults, Johns Hopkins Medicine. DOI: 10.1001/jamainternmed.2023.5619

Journal information: Johns Hopkins Medicine