The relationship between the Maudsley Personality Inventory and the course of affective disorders.
A group of 99 patients with a primary affective disorder was given the Maudsley Personality Inventory on admission to hospital and also four years later as part of a follow-up study. The patients were allocated to one of four operationally defined diagnostic groups: phobic anxiety depersonalization state, simple anxiety state, reactive depression and endogenous depression.

It was found that MPI scores are influenced by the prevailing mental state of the patients. The presence of affective illness was associated with a marked increase in neuroticism and a less marked decrease in extraversion; changes in the opposite direction occurred following recovery.

A comparison of the N and E scores obtained during the key illness and at follow-up reflected the tendency for male patients with neurotic disorders to make a good recovery while female patients with neurotic disorders tended to remain more permanently disabled. Patients with endogenous depression were distinguished from the neurotic diagnostic groups by lower N scores and higher E scores, both at key illness and at follow-up.

It is suggested that the MPI can assist in the differentiation of affective disorders as regards outcome if the relative contributions of personality and illness to the scores obtained are considered.

Personality differences were demonstrated in patients after recovery from three forms of affective disorders: the female phobic anxiety group, the male simple anxiety group, and the endogenous depression group.

In the diagnostic groups of reactive depression and endogenous depression, the N scores obtained at key illness of patients who subsequently recovered were significantly lower than the scores of patients who remained unwell.

The inclusion of information regarding age, sex, diagnosis and MPI scores of patients with affective disorders was found to increase the accurate prediction of outcome by a highly significant degree over the rate obtained when none of these variables was employed.