Is bipolar disorder more common among individuals with higher intelligence and exceptional creativity? Epidemiological evidence so far is not good enough for firm conclusions.Studies that support this notion has problems ( for example: not having enough power to detect the link).Both bipolar disorder and high intelligence are uncommon in general population and only a large study can look in to this relationship.
CR Gale, GD Batty,AM McIntosh, DJ Porteous, IJ Deary and F Rasmussen used data from over a million Swedish men to investigate this. Military Service Conscription Register ( medical examination, intelligence assessment, interview by psychologist, assessment from psychiatrist if needed) and hospital discharge register provided the key information.
0.3% were hospitalised with bipolar disorder during the follow-up period (The mean follow-up period was 22 years). Of this 3174 men, 1079 (34%) had the bipolar disorder in a pure form (.ie 74% had many other conditions diagnosed during this period).
Risk of hospitalisation with any form of bipolar disorder fell in a stepwise manner as intelligence increased.Adjustment for age, year of conscription, conscription-testing centre, parental age and parental social class had little effect on this association. This suggest that high intelligence may confer resilience to several forms of psychiatric comorbidity.
What about those with pure bipolar disorder? Men with the highest intelligence, particularly as regards verbal and technical ability, were at increased risk compared with those of average ability. This association was stronger if a more restrictive definition of bipolar disorder is used. There is an increased risk of pure bipolar disorder in men with the highest verbal or technical abilities.
Authors remind readers that IQ is not an effective discriminator of which individuals go on to have hospital treatment for this disorder as hazard ratios are of small magnitude.
Limitations:Cases of bipolar disorder during the follow-up period were defined on the basis of hospital admission ie only those who were admitted were accounted for.Diagnosis was made clinically.( i.e. no standardised interview).Only men were studied.
Conclusions: High intelligence may be a risk factor for bipolar disorder ( in its pure form) at least in men.
Summary of the article:
Gale CR, Batty GD, McIntosh AM, Porteous DJ, Deary IJ, Rasmussen F.Mol Psychiatry. 2013 Feb;18(2):190-4.