No evidence for verbal memory impairment in individuals putatively at risk for bipolar disorder

Abstract 

Background

Hypomanic temperament and rigid personality are putative risk factors for affective episodes and even bipolar disorder. Individuals with bipolar disorder exhibit neuropsychological impairments, especially memory difficulties, not only during mood episodes but also when they are euthymic. Such cognitive impairments may also constitute a risk factor for bipolar disorder. The purpose of the present study was to investigate the presence of memory difficulties in individuals with hypomanic and rigid personality traits.

Methods

Study participants were 6000 German students recruited from high schools, colleges, and vocational schools in Germany. The students completed the Hypomanic Personality Scale and the Rigidity subscale of the Munich Personality Test. Four groups of students were selected from this sample based on their scores in the Hypomanic Personality Scale and Rigidity subscale: individuals with (1) hypomanic temperament, (2) rigid temperament, or (3) hypomanic-rigid temperament and (4) control participants. These students (n = 153) completed the Rey-Auditory Verbal Learning Test, a well-established measure of verbal learning and memory, as well an IQ test (Leistungsprüfsystem).

Results

Multiple regression analyses indicated that sex and IQ, but not temperament, predicted learning of the Auditory Verbal Learning Test word list, the number of words recalled at short-delayed recall, and recognition.

Limitations

The risk for affective disorders was only defined by psychometric measures, and we did not control for family history of bipolar disorders.

Conclusions

Hypomanic temperament and Rigid personality were not associated with verbal learning and memory. Cognitive impairment may be associated with repeated mood episodes rather than constituting a risk factor for bipolar disorder.