The general factor of psychopathology: Precursors and consequences

It is quite common that individuals who have one psychiatric condition also qualify for other psychiatric conditions. This observation questions the conventional belief that different diagnoses are independent and instead implies the possibility of a set of factors that increases risks for several types of mental health problems.

These risk factors can be captured via a so-called hierarchical model that consists of one general factor that increases risk for all psychiatric conditions (sometimes labeled "p factor"), in addition to a set of specific factors that increase the risk for a subset of conditions (e.g., a specific internalizing dimension that increases risk for only depression and anxiety).

In her thesis, Ph.D. student Cen Chen at the Department of Medical Epidemiology and Biostatistics performed multivariate analyses on data from nationwide Swedish registers and the Swedish Twin Register to examine how the general psychopathology relates to genetics, cardiometabolic complications and pain, and suicidal behavior.

What are the most important results in your thesis?

Chen: In the first study, we examined how genetics contributed to general psychopathology. Past family and twin studies have suggested that genetics play an important role behind the tendency for some individuals to meet the criteria for more than one psychiatric condition. However, those designs could not rule out potential alternate explanations.

Therefore, we applied a relatively novel design to examine the direct effect of genetics on general psychopathology. Specifically, we observed that the sibling who by chance inherited a higher genetic risk for psychiatric conditions compared to their brother or sister, also tended to have more co-occurring psychiatric conditions. This implies that genetics is an important reason for why some individuals tend to suffer several psychiatric conditions.

In the second study, we observed that individuals with several psychiatric conditions in young adulthood had an elevated risk of cardiometabolic conditions in middle adulthood. As these associations did not appear attributable to potential confounds shared by siblings, one possibility is individuals with several psychiatric conditions lead unhealthier lifestyles, which in turn increases their risk of later health problems.

In the third study, we observed that individuals who self-reported having multiple types of chronic pain were at increased risk of suicide ten years later. Clinicians might find it useful to assess not only specific types of pain but also total pain scores.

What do you think should be done in future research?

Chen: In order to further define general psychopathology, more studies are needed to understand the structure, reliability, and stability of various factors of psychopathology over time and throughout different stages of life.

Second, from a clinical perspective, different disorders often respond to the same treatments. However, it's unclear if a transdiagnostic approach could be beneficial when deciding treatments for broader psychopathology and related life impairments. Furthermore, confirming whether psychotropic medication can impact the general psychopathology would strongly support the case for psychological interventions.

Third, the findings presented in my thesis indicate the presence of a factor that explains significant variance across chronic pain conditions. It might be useful for future studies to repeat the present analyses using different samples, especially exploring the relationship between pain comorbidity and other adverse life outcomes."