MMPI as a measure of subthreshold and residual psychopathology among the offspring of lithium responsive and non-responsive bipolar parents.

Objectives: In bipolar adults, the Minnesota Multiphasic Personality Inventory (MMPI) can detect residual symptoms and confirm completeness of remission, thus helping to predict response to lithium prophylaxis. In the high-risk and early onset bipolar populations, the association of the MMPI with clinical course and treatment response has not yet been studied. The present study compares MMPI profiles completed by the well or remitted offspring of two groups of bipolar parents divided on the basis of parental response to long-term lithium.

Methods: As part of an ongoing prospective longitudinal high-risk study, offspring of bipolar parents determined to either respond or not respond to long-term lithium monotherapy completed the MMPI. At the time of MMPI completion, offspring were determined to be either well (unaffected) or clinically remitted (affected but euthymic) based on repeated prospective KSADS-PL format interviews conducted by a research psychiatrist and reviewed on a blind consensus basis.

Results: While there was no difference in the MMPI scores between subgroups of unaffected offspring, there was a significant difference in profiles between remitted offspring. Specifically, affected offspring of lithium non-responders showed significantly higher average scores on scales 6, 8 and 0 compared with affected offspring of lithium responders. These findings are consistent with the differences in MMPI profiles taken at optimum between the respective parent subgroups.

Conclusions: The findings confirm the clinical observation that the affected offspring of lithium responders suffer from episodic fully remitting mood disorders, while the affected offspring of lithium non-responders suffer from mood disorders with incomplete remission. Further, the nature of the residual symptoms as indicated by the abnormal MMPIs support the view of heterogeneity of the bipolar diagnosis. The relevance to treatment response is discussed.