Adolescent decline in verbal ability can predict psychosis in adulthood

It's well recognized that cognitive deficits in childhood or adolescence typically precede the onset of psychosis, but the studies done up until now have not determined whether the association is prodromal (an early symptom of psychosis itself) or neurodevelopmental (problems with brain development and maturation that set the stage for later psychosis). A study just published in JAMA Psychiatry offers strong evidence that verbal decline in adolescence reflects neurodevelopmental defects that significantly increase the lifetime risk for psychosis. The authors note:

"Clear evidence from many prospective, population-based studies indicates that patients who develop psychosis in adulthood experienced various cognitive deficits during childhood and adolescence. However, it is unclear whether these deficits become more severe during adolescence."

So they set out to...

"...assess the influence of cognitive developmental trajectories in adolescence and young adulthood on the risk for psychosis in adulthood."

They conducted a longitudinal cohort study of four populations of adolescent boys and young men born in in 1953, 1967, 1972, and 1977, totaling 10,717 individuals. These subjects were followed through December 2006 and tested for verbal, spatial, and inductive ability at age 13 years. Equivalent tests were performed during army conscription at 18 years (this was done in Sweden). The authors correlated this data with hospital admissions for nonaffective or affective psychoses in adulthood. A striking link with decline in verbal ability emerged:

"A relative decline (compared with the unaffected population) in verbal ability between ages 13 and 18 years was associated with increased risk for schizophrenia and for other nonaffective and affective psychoses. Decline between ages 13 and 18 years was a much stronger predictor of psychosis than the verbal ability score at age 18 years alone. The association remained significant after adjustment for urbanicity, parental educational level, and family history of psychosis and persisted when cases with onset before age 25 years were excluded, indicating that this was not a prodromal effect."

Note for clinicians and parents: multiple biological factors can conspire to interfere with neurodevelopment, manifesting as disturbances in cognitive and emotional function. A range of these with reference to pertinent tests, validating citations and practical remediation is available in the Parents' Guide To Brain Health. The authors conclude:

"A relative decline in cognitive performance in adolescence and young adulthood, particularly in verbal ability, is associated with increased risk for psychosis in adulthood, and a relative decline in verbal ability between ages 13 and 18 years is a stronger predictor of psychosis than verbal ability at age 18 years alone. This suggests an impairment of late neurodevelopment affecting the acquisition of verbal skills in adolescent boys and young men who later develop psychosis."