Research news in brief and online first at the MJA

Older adults generate as many new brain cells as young people

Researchers from Columbia University in the US have shown for the first time that healthy older men and women can generate just as many new brain cells as younger people. Previous research has suggested that the adult brain was hard-wired and that adults did not grow new neurons. A new study, published in Cell Stem Cell, suggests that many senior citizens remain more cognitively and emotionally intact than commonly believed. The researchers autopsied hippocampi from 28 previously healthy individuals aged 14–79 years who had died suddenly. This is the first time that researchers have looked at newly formed neurons and the state of blood vessels within the entire human hippocampus soon after death. The researchers had determined that the study subjects were not cognitively impaired and had not suffered from depression or taken antidepressants, which had previously been found to affect the production of new brain cells. In rodents and primates, the ability to generate new hippocampal cells declines with age. Waning production of neurons and an overall shrinking of the dentate gyrus, part of the hippocampus thought to help form new episodic memories, was believed to occur in ageing humans as well. The researchers found that even in the oldest brains they studied, there were similar numbers of proliferating progenitor and immature neuron cells to those in younger brains. However, they also found that quiescent stem cell pools, angiogenesis and neuroplasticity decline in older individuals. The researchers surmised that reduced cognitive-emotional resilience in old age may be caused by this smaller pool of neural stem cells, the decline in vascularisation, and reduced cell-to-cell connectivity within the hippocampus.

Connections between brain regions linked with financial risk tolerance

Connections between two areas of the brain, the amygdala and the medial prefrontal cortex (mPFC), have been implicated previously in the development of affective disorders such as depression and anxiety. New research, published in Neuron, suggests that this same brain system plays a role in a person’s ability to tolerate economic risk. Researchers at the University of Pennsylvania studied 108 healthy young adults. Participants were asked to answer several questions involving their comfort with financial choices – each involving various levels of risk and reward. They faced over 120 different scenarios involving the risk of making more or less money. The study identified individuals ranging from extremely risk-averse all the way to risk-seeking. Separately, using magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI), the researchers measured the structural and functional connections between various parts of the participants’ brains, homing in on the amygdala/mPFC system. They also measured the size of the amygdala, including volume of gray matter and white matter. To make an assessment of an individual’s risk tolerance, the scientists correlated their assessment of participants’ risk tolerance with the measures of brain structural and functional connectivity. Individuals with higher tolerance for risk in the study possessed a larger amygdala (more gray matter) and more functional connections between the amygdala and mPFC as measured by MRI. And higher risk tolerance was identified in individuals with fewer structural connections or pathways between these areas, as measured by DTI. The researchers plan on collaborating with financial planning organisations to see how these brain system findings can be used as a marker for risk tolerance involving larger economic-based decisions.

Most COPD cases linked to childhood risk factors

Three-quarters of chronic obstructive pulmonary disease (COPD) cases have their origins in poor lung function pathways beginning in childhood. These pathways are associated with exposures in childhood, and amplified by factors in adulthood, according to a cohort study published in The Lancet Respiratory Medicine journal. While smoking remains the biggest risk factor for COPD, the study shows that childhood illnesses (such as asthma, bronchitis, pneumonia, allergic rhinitis and eczema) and exposures to parental smoking are also linked to the disease. A second study in the journal also suggests that there could be a window of opportunity during childhood to reduce the risk of poor lung function in later life. Both studies identified pathways for how lung function changes over life, which are associated with different risk factors and disease risk in later life. The authors say that these insights are important for lung disease prediction, prevention and treatment.

Online first at the MJA

9 April Narrative review: Climate change: a brief overview of the science and health impacts for Australia
Hanna and McIver; doi: 10.5694/mja17.00640
Global warming is associated with intensifying climatic extremes and disruption to human society and human health … OPEN ACCESS for one week.

9 April Podcast with Dr Elizabeth Hanna, Honorary Senior Fellow at the Climate Change Institute at the Australian National University … OPEN ACCESS permanently.

9 April Perspective: Whole genome sequencing provides better diagnostic yield and future value than whole exome sequencing
Mattick et al; doi: 10.5694/mja17.01176
The higher cost of whole genome sequencing is justified through better diagnostic yields and the potential for future analysis.

9 April Perspective: Disease-modifying approaches for Parkinson
Lewis; doi: 10.5694/mja17.01135
A new era of disease modification in the field of neurodegeneration has differing approaches that will hopefully improve outcomes for people with Parkinson disease … OPEN ACCESS for one week.

9 April Podcast with Professor Simon Lewis, professor of Cognitive Neuroscience at the University of Sydney’s Brain and Mind Centre … OPEN ACCESS permanently.

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