Changes in Personality Traits Predict Early Career Outcomes

Post by Shireen Parimoo

What's the science?

Are conscientious people more likely to be satisfied with their career? Several studies show that career outcomes are associated with personality traits. For example, traits like emotional stability and conscientiousness are related to higher income and occupational attainment. Although these traits are largely stable aspects of our personality, they also tend to vary across different life stages, suggesting that our personality undergoes changes over the course of our lifetime. It is particularly important to understand the nature of personality growth in early adulthood because it is a critical period in career development. This week in Psychological Science, Hoff and colleagues investigated how personality changes from late adolescence to early adulthood are related to various career outcomes.

How did they do it?

The authors followed two large, nationally representative samples of adolescents in Iceland (Sample 1 N = 485, Sample 2 N = 1290), beginning when participants were students (15-17 years old) to when they were young adults (27-29 years old). During this period, they measured participants’ personality traits at three (Sample 1) and five time points (Sample 2) using the NEO Five-Factor Inventory, a personality test that provides scores on the traits of openness, conscientiousness, extraversion, agreeableness, and emotional stability. They used linear growth-curve analysis to assess participants’ baseline scores in adolescence on each personality trait and the rate at which their scores changed over time.

After approximately 12 years, the authors recorded subjective career outcomes such as job and career satisfaction, as well as objective measures like monthly income, highest degree obtained, and occupational prestige. Occupational prestige was based on the most recent job held by the participants. To rate occupations on status and prestige, they used the online tool O*NET that classified jobs into different titles (e.g., surgeon) and assigned each title a rating on various work-value dimensions like Achievement and Recognition. To investigate the relationship between personality changes and career outcomes, the authors specified a separate path model (a statistical approach) for each outcome, including personality traits as predictors and controlling for the effect of gender.

What did they find?

Agreeableness, conscientiousness, and openness increased with age, whereas emotional stability did not change, and extraversion scores decreased. Higher conscientiousness, emotional stability, and agreeableness in adolescence were associated with higher degree attainment in the future. Similarly, baseline levels of emotional stability and conscientiousness (Sample 1) as well as openness and extraversion (Sample 2) were related to greater future occupational prestige. In fact, emotional stability and conscientiousness in adolescence were positively related to nearly all career outcomes, highlighting their importance in future career development. Moreover, changes in personality traits were also predictive of career outcomes. For example, higher income and career satisfaction were associated with increases in emotional stability from adolescence to young adulthood. Similarly, although extraversion decreased in general, increases in extraversion were related to higher career and job satisfaction. Overall, these results show that personality traits in adolescence predict objective measures of career success whereas certain changes in personality traits over time are linked to subjective career outcomes.

What's the impact?

These results are exciting because they highlight both enduring and mutable aspects of personality development in the transition from adolescence to adulthood. In addition, this is the first longitudinal study to demonstrate how personality traits in adolescence and young adulthood predict objective and subjective career outcomes, respectively. Future research can further examine the direction of the relationship between personality changes and career success.

Hoff et al. Personality Changes Predict Early Career Outcomes: Discovery and Replication in 12-Year Longitudinal Studies. Psychological Science (2020). Access the original scientific publication here.

GABAergic Interneuron-Astrocyte Interaction Facilitates Complex Behaviours

Post by D. Chloe Chung

What's the science?

Interneurons that release a type of inhibitory neurotransmitter called GABA regulate complex behaviours such as decision-making. Along with other neurotransmitters, GABA released at synapses can be detected by astrocytes that express receptors for GABA (GABABRs). Until now, it has not been well understood whether interaction between GABAergic interneurons and astrocytes can impact complex behaviours. This week in Nature Neuroscience, Mederos and colleagues found that GABAergic signaling to astrocytes plays an important role in modulating behavioural outcomes, by applying electrophysiology and optogenetics to a novel mouse model.

How did they do it?

To test the functional role of astrocytes sensing GABA, the authors made a new mouse model that is designed to lack astrocytic GABABRs in the medial prefrontal cortex (mPFC), a brain area that controls decision-making. These mice, along with the control mice, underwent a behavioural test that measures working memory and decision-making. Specifically, mice were made to choose which arm of the simple maze (T-maze) to enter based on their spatial memory (i.e. which arm they previously took food from). During the behavioural test, the authors monitored dynamic changes in neural activity in the mouse brain using electrophysiological techniques. In parallel, the authors used a slice of mouse mPFC to perform ex vivo recordings of neuronal firing while mimicking interneuron-astrocyte signaling. To understand direct consequences of mPFC astrocyte activation on mouse behaviors, the authors injected virus into the brains of both control mice and genetically modified mice to specifically stimulate astrocytes using melanopsin, a light-sensitive G-protein.

What did they find?

The authors first observed that mice without GABABRs in the mPFC astrocytes had impaired working memory and decision-making compared to control mice, as shown by the T-maze test. From simultaneous electrophysiological recordings, the authors found that low gamma oscillations (30–60 Hz) in the brain were substantially reduced while mice were experiencing impaired decision-making. These findings collectively indicate that deficits in GABAergic astrocyte signaling disrupted brainwaves and neuronal firing properties that are critical for decision-making, subsequently impairing behavioural outcomes. Ex vivo mPFC recording further revealed that interaction between GABAergic interneurons and astrocytes through GABABRs importantly regulates the inhibitory neural circuitry. Interestingly, when the authors optogenetically activated mPFC astrocytes, control mice performed better at the decision-making test. The observed improvement in decision-making was accompanied by enhanced neuronal firing and gamma oscillations, suggesting that activation of astrocytes in the mPFC can markedly improve cognitive capacity. Based on this finding, the authors performed a similar optogenetics experiment with mice that lack GABABRs in mPFC astrocytes and found that optogenetic stimulation of mPFC astrocytes rescued behavioural deficits. In other words, mice that were once impaired in their decision-making due to the loss of GABAergic astrocyte signaling behaved similarly to naïve mice upon selective activation of astrocytes.

What’s the impact?

This study is the first to demonstrate that GABAergic signaling involving interneurons and astrocytes in the mPFC is critical in modulating decision-making. Past studies have reported that behaviour can be impacted by astrocytes in brain regions other than mPFC such as the hippocampus and amygdala. This work expands the functional role of astrocytes, presenting them as essential players in facilitating complex behaviour controlled by mPFC. As the authors suggested, given the variety of interneurons in the brain, it will be interesting to further investigate whether other types of interneurons can also interact with astrocytes in a similar manner.

Mederos et al. GABAergic signaling to astrocytes in the prefrontal cortex sustains goal-directed behaviors. Nature Neuroscience (2020). Access the original scientific publication here.

Air Pollution is Associated with Increased Amyloid-β Plaques in Older Individuals with Cognitive Impairment

Post by Amanda McFarlan

What's the science?

Alzheimer’s disease is a neurodegenerative disease associated with the accumulation of amyloid-β plaques and neurofibrillary tangles. It has been suggested that environmental factors like air pollution may contribute to the development of Alzheimer’s disease. Indeed, human and animal studies have provided evidence that exposure to air pollution may lead to increased production and deposition of amyloid-β in the brain. This week in JAMA Neurology, Iaccarino and colleagues investigated whether increased levels of air pollution are associated with the accumulation of amyloid plaques in the brains of older individuals with cognitive impairment.

How did they do it?

The authors obtained data from the Imaging Dementia—Evidence for Amyloid Scanning (IDEAS) study which assessed amyloid-β accumulation in over 18 000 participants with cognitive impairment using positron emission tomography (PET). They also obtained demographic information as well as residential zip code data for all participants in the study. Then, they used the Downscaler model provided by the United States Environmental Protection Agency to gather data on the air quality, as measured by fine particulate matter (particles with a diameter less than 2.5 μm) and ground-level ozone, from 2002-2003 (~14 years prior to the PET scan) and from 2015-2016 (~1 year prior to the PET scan). Using this data, the authors performed statistical analyses to determine whether participants living in areas with higher levels of fine particulate matter and ground-level ozone were more likely to be positive at the amyloid-PET scan, indicating brain amyloid-β accumulation. 

What did they find?

The authors found that the probability of detecting amyloid-β in the participants’ PET scans was significantly increased in areas with higher concentrations of fine particulate matter. They used marginal effects analyses to show that for every 1 μg/m3 increase in fine particulate matter, the probability of having a positive amyloid PET scan was +0.5% in 2002-2003 and +0.8% in 2015-2016. The association between positive amyloid PET scans and fine particulate matter remained statistically significant after adjusting for covariates including sex and US Census tract (distinct geographic regions that are used for the exchange of geographic and statistical data) random effects. Higher concentrations of ground-level ozone, on the other hand, were not associated with positive amyloid PET scans.

What’s the impact?

This study shows that the regional concentration of fine particulate matter in the air is associated with increased accumulation of amyloid-β plaques in the brains of older individuals with cognitive impairment. These findings suggest that airborne pollutants may be associated with Alzheimer’s disease pathology. These findings can inform public health policy decisions, as pollution levels may contribute to an individual’s risk of developing Alzheimer’s and dementia.

Iaccarino et al. Association Between Ambient Air Pollution and Amyloid Positron Emission Tomography Positivity in Older Adults With Cognitive Impairment. JAMA Neurology (2020). Access the original scientific publication here.