week 1: Caspi et al (2020) longitudinal assessment of MH disorders in Dunedin cohort study

What was the primary objective of the Disorders and Comorbidities study regarding mental health?

The primary objective was to describe mental disorder life histories across the first half of the life course, testing the hypothesis that people experience many different kinds of disorders across diagnostic families when followed for 4 decades, rather than being limited to a current diagnosis.

Describe the age range and frequency of mental health assessments conducted in the study

Mental health assessments were conducted 9 times from ages 11 to 45 years, following participants born in New Zealand form 1972 to 1973.

What proportion of participants experienced the onset of a mental disorder by adolescence (ages 11-18)?

Approximately 59% of participants in the Dunedin Birth Cohort Study experienced the onset of a mental disorder by age 18.

How common was it for participants with a mental disorder to have accumulated comorbid diagnoses by age 45?

By age 45 years, 85% of participants who had even met the criteria for a mental disorder had acclimated comorbid diagnosis.

What is the p-factor, as identified in this study?

The p-factor is a general factor of psychopathology identified through confirmatory factor analysis of symptom-level data across 4 decades, summarising participants’ mental disorders life histories life histories and indicating a general vulnerability to various disorders.

How was early neurocognitive functioning at age 3 associated with later mental disorder life histories (p-factor scores)?

Poor neurocognitive functioning at age 3 years was associated with higher p-factor scores later in life, indicating that early compromised brain health was linked to more extensive mental disorders life histories.

The study found an association between higher p-factor scores and cognitive changes from childhood to adulthood. Describe the finding.

Higher p-factor scores were associated with greater cognitive decline from childhood to adulthood, meaning individuals with more generalised psychopathology experienced a steeper decrease in cognitive ability over time.

What was the association found between higher p-factor scores and brain age at midlife?

Higher p-factor scores were associated with older brain age at midlife, suggesting that more extensive mental disorders life histories were linked to accurate structural brain ageing.

According to the study, what does the pattern of shifting diagnoses across different disorder families suggest about the nature of mental disorders?

The pattern of shifting diagnoses across different disorder families suggests that mental disorders are not static entities confined to specific diagnostic categories but rather represent a dynamic process where individuals move between and accurate various forms of psychopathology over time.

What public health implication is highlighted by the study’s finding that sustained mental wellness is rare?

The finding that sustained mental wellness is rare, with the most individuals experiencing at least one bout of mental disorder, suggests a need for public health education to reduce stigma and promote earlier treatment uptake, as well as a shift in public expectation regarding mental health.

What was the main objective of the Dunedin Birth Cohort Study regarding mental health?

The primary objective was to describe the life histories of mental disorders among participants from birth to age 45. Unlike traditional approached that focus on a single diagnosis at a specific point in time, this study aimed to understand how mental disorders manifest and evolve across the first half of the life course by repeatedly assessing participants over four decades.

What is the key finding about the typical pattern of mental disorders over a person’s lifetime according to this study?

The study found that most people who experience mental disorders do not have a single, pure diagnosis that persists throughout their lives. Instead, their mental disorder life histories often shift among different types of disorders across various diagnostic families (internalising, externalising, and thought disorders). The predominant pattern observed was one of successive and diverse diagnosis accumulating over time, particularly for those with an early age of onset.

How prevalent are mental disorders over the life course according to the Dunedin study?

The study indicates a very high lifetime prevalence of mental disorders. By age 45, a cumulative 86% of the cohort had met the criteria for at least one mental disorder. This suggests that sustaining enduring mental health is relatively rare, and experiencing at least one episode of mental disorder is a common occurrence over the life course.

What is the significance of an early age of onset for mental disorders?

An early age of onset, particularly in adolescence, was strongly associated with a more complex and enduring mental disorders among participants life history. Participants whose disorders began earlier tended to experience disorders at more assessment points across the stray period and met the criteria for a greater diversity of different disorder types. This highlights the importance of early identification and intervention.

What is the “p-factor” and how does it relate to mental disorders life histories?

The “p-facto” is a general factor of psychopathology identified through confirmatory factor analysis of symptom-level data collected over four decades. It represents a single dimension that summarises the variation in individuals’ mental disorder life histories. Higher p-facto scores indicate a more extensive history of mental disorders, including younger age at onset, longer duration, and greater diversity of diagnoses.

What associations were found between mental disorder life histories (summarised by the p-factor) and brain health?

The study Lund significant associations between higher p-factor scores (indicating more extensive mental disorder life histories) and compromised brain function. Specifically, higher p-factor score were linked to poorer neurocognitive functioning at age 3, greater cognitive decline from childhood to adulthood, and an older estimated brain age at midlife (age 45).

What are the implications of these findings for current psychiatric diagnosis and treatment approaches?

These findings challenge the traditional emphasis on diagnosis-specific research and clinical protocols. Since most individuals experience a variety of disorders across their lives, focusing solely on a single current diagnosis may not adequately inform about the cause or prognosis of the study suggests a need for a life-course perspective that considers the dynamics of mental disorders over time and highlights the potential value of transdiagnostic interventions that build skills for maintaining enduring mental health.

What are some of the limitations and strengths of the Dunedin Study regarding these findings?

Limitations include that the cohort is predominately white and from one country and historical period, although previous findings have been replicated elsewhere. The study was also left-hand censored at age 11 and right-hand censored at age 45, and diagnostic criteria evolved over the study period. However, a major strength is its longitudinal design with repeated, systematic, and standardised mental health assessments of a population-representative cohort over four decades, regardless of treatment status. This allowed for a comprehensive view of mental disorder life histories that is not susceptible to biases inherent in clinical registers or respective recall.