In collaboration with colleagues at the Centre for Developmental Psychiatry and Psychology, Monash University, Australia (NIH/NIMH MH061809; PI: Hofer/Tonge), we examined risk and resilience factors in the evolution of psychopathology in an internationally unique cohort of young people with intellectual deficits. In a paper published in JAMA (Einfeld et al., 2006), we found that high initial levels of behavioral and emotional disturbance declined only slowly over time, remaining high into young adulthood. Overall severity of psychopathology was similar across mild to severe range of intellectual disability. Psychopathology declines more in boys than girls over time, and more so in those with mild intellectual disability compared with those with severe intellectual disability. This trend is observed in each of the subscales except Social Relating, which increases over time. These findings provide solid evidence that the problem of psychopathology comorbid with ID is both substantial and persistent and thus demands a public health response.
In a follow-up paper (Hofer et al., 2009), we report associations among individual differences in level, rate of change, and occasion-specific variation across subscales of the Developmental Behavior Checklist in a sample (n=506) aged 5-19 years. Correlations among the five DBC subscales ranged from .43 to .66 for level, .43 to .88 for rate of change, and .31 to .61 for occasion-specific variation, with the highest correlations observed consistently between Disruptive, Self-Absorbed, and Communication Disturbance behaviors. These interdependencies among dimensions of emotional and behavioral disturbance provide insight into the developmental dynamics of psychopathology from childhood through young adulthood.