Neurocognition

Advancing clinical science involves understanding the causes of depression, anxiety, obsessive-compulsive disorder, post-traumatic stress disorder, and other common mental disorders (CMDs), both immediate and long-term. Our research centers on executive functioning (EF)-specific vulnerability models, suggesting that deficits in EF hinder the reframing of unhelpful beliefs, emotional regulation, and decision-making, ultimately predicting future CMDs and symptoms. EF encompasses higher-order cognitive control essential for planning, prioritization, idea implementation, conflict resolution, and daily mental processes. Understanding cognitive function (such as EF) and CMD evolution is especially crucial in societies with aging populations, increased life expectancy, and rising neurocognitive disorders, providing insights for strategic preventive biopsychosocial interventions.

However, most research has used cross-sectional designs, showing only group differences in risk factors among individuals. In contrast, our research relies on longitudinal datasets and consistently supports vulnerability models across diverse samples. Using Poisson and negative binomial regressions, we discovered that lower performance on inhibition, set-shifting, working memory (WM), inductive reasoning, and global cognition tests predicted increased severity of anxiety disorder symptoms and diagnoses in adults 9 years later. These findings support vulnerability models and hold true across various age groups, including young (18-40 years), middle-aged (41-64 years), and older (≥65 years) community adults (Zainal & Newman, 2018a).

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Nonetheless, traditional regression studies with only two time points investigating the links between MH symptoms and executive functioning (EF) have limitations in advancing clinical science. They overlook the nesting of repeated measures within individuals, which goes against the assumption of error independence, and fail to capture change-to-future change patterns over time. To address this, we utilized bivariate dual latent change score (BLCS) modeling, a longitudinal structural equation modeling (SEM) type, and reproduced similar findings across multiple studies. In individuals, a more significant decline in spatial cognition, processing speed, working memory (WM), verbal fluency, and global EF at one point in time predicted a sharper increase in traits like negative affect, depression symptoms, and life dissatisfaction at the subsequent time point, spanning 8 to 23 years in various adult samples (Zainal & Newman, 2021a, 2021c, 2022c). These studies emphasize the significance of comprehending the mutual change-to-future change connections between risk factors and mental health (MH) problems over extended durations in psychology. Such knowledge can guide individualized strategies for diagnosis, education, prevention, and intervention, especially in cognitive-behavioral therapies (CBTs) and similar treatments for CMDs. These psychological treatments aim to improve EF and overall quality of life while addressing symptoms of CMDs.

Discovering support for executive functioning (EF)-focused vulnerability models in multiple datasets piqued our interest in exploring the opposite direction. As a result, we investigated the concepts of EF-focused scar theories, which propose that untreated, elevated common mental disorder (CMD) symptoms can deteriorate EF and related abilities over prolonged durations. These "scar" processes may result from unhealthy lifestyle choices, such as poor diet and physical inactivity, and the accumulation of allostatic load in the body. Allostatic load refers to chronic wear and tear on the hypothalamic-pituitary-adrenal (HPA) axis due to the buildup of biomarkers linked to chronic stress and CMD symptoms, such as cortisol and proinflammatory cytokines, over long periods. Within individuals, a nine-year increase in pathological worry among community adults preceded a future nine-year decline in inhibition and set-shifting, with moderate-to-large effect sizes (Zainal & Newman, 2021d). Likewise, 3 additional studies revealed that a notable rise in depression symptoms, an inclination toward feeling negative emotions, and life dissatisfaction were significant predictors of more pronounced decline in EF-related abilities within individuals (Zainal & Newman, 2021a, 2021c, 2022c).

We also harness longitudinal network analysis, which goes beyond structural equation modeling (SEM) by identifying pivotal components of variables X and Y that mutually influence each other over time. Identifying these crucial elements is essential for optimizing treatment and potentially addressing factors contributing to common mental disorder (CMDs). In the context of executive functioning (EF)-focused scar and vulnerability theories, our research underscores that low positive affect and high somatic symptoms, rather than anxiety severity, depressed mood, or interpersonal issues, consistently predicted declines in verbal WM, processing speed, and face recognition test scores (Zainal & Newman, 2023b). These results remained valid even when considering various biopsychosocial factors in a sample consisting only of females (Zainal & Newman, 2023b). Likewise, when age was adjusted for in these models, heightened anxious and depressed moods, rather than other symptoms such as agitation, irritability, and apathy, consistently predicted EF components in both older adult men and women in the community (Zainal & Newman, 2023c). In summary, both SEM and longitudinal network analysis offer more substantial backing for EF-focused scar theories than vulnerability models. Given the consistent emergence of anxious and depressed mood, along with somatic symptoms, as essential risk factors of future declines in EF domains, it is crucial to prioritize alleviating these symptoms in adults for prevention and treatment. Emphasizing the protective aspect of coping skills, such as mindset reframing and relaxation, can enhance evidence-based cognitive-behavioral, mindfulness-based, and related therapies to preserve EF and cognitive functioning.

Additionally, our research has explored cognitive processes such as social cognition, decision-making, and intellectual curiosity. In one study, we discovered that inducing worry compared to relaxation improved the accuracy of individuals with generalized anxiety disorder (GAD) in understanding others' thoughts and feelings, mainly when the content was negative (Zainal & Newman, 2018b). Furthermore, using Bayesian analysis, we observed that patients with obsessive-compulsive disorder (OCD) experiencing more severe ritualistic compulsion symptoms encountered increased deficits in decision-making over time (Zainal et al., 2023). These results highlight the significance of giving priority to reducing compulsive behaviors among OCD symptoms. In a related decade-long study, we used bivariate dual latent change core (BLCS) and the random intercept cross-lagged panel model to demonstrate that a decline in the need for cognition (intellectual curiosity) at one-time point preceded a subsequent increase in depression and anxiety symptoms (Zainal & Newman, 2022a, 2023a). These findings emphasize the importance of reducing negativity biases, enhancing problem-solving and decision-making abilities, and nurturing curiosity via purpose-driven activities aligned with one's values.

MHI = Mental Health Inventory (anxiety and depression symptom severity); NFC = need for cognition (intellectual curiosity); T1 = Time 1; T2 = Time 2; T3 = Time 3; T4 = Time 4; T5 = Time 5; T10 = Time 10.