Cognitive abilities are affected in different ways in various mental disorders. Some of these deficits are seen only during the active period of illness, but some changes are observed prior to the onset of mental disorder as well as in remission state. It is also possible that some changes are progressive, for example studies suggest that individuals with depression is likely to be at increased risk for dementia. What about the risk of dementia among individuals with bipolar disorder ?
Studies by Kessing et al ( 1994-2010) using the national registry data in Denmark revealed that patients with a history of admission for bipolar disorders had an increased risk of later diagnosis of dementia compared with general population.
Wu K-Y et al investigated this relationship using Taiwanese insurance database.98.4% of population is enrolled on this to receive clinical services. A random sample from a 10 year period was used in this analysis. For inclusion as eligible cases, subjects had to have at least three consistent diagnoses of dementia and be older than 45 years.Down syndrome individuals were excluded. Control group was those with no claims for dementia during the same period. For the exposure variable ( i.e. bipolar disorder), only those who had had at least three consistent bipolar diagnoses in either inpatient or outpatient claims data were included. Confounding factors (cardiovascular risk factors, medical comorbidities, and psychiatric disorders) were taken in to account in the regression models.
Subjects with bipolar disorder had a 4 fold higher risk of dementia than the controls [adjusted odds ratio (aOR) = 4.07; 95% CI: 3.08–5.37] . Risk was high for senile and pre senile dementias.
Claims data have the usual limitations. i.e. regarding the reliability and validity of the diagnoses of bipolar disorder and dementia. However only patients who had at least three consistent diagnoses (for both bipolar disorder and dementia) identified from out- patient and inpatient claim data were only included. Medical records were not available to link the claim data.Detailed information (clinical subtypes of dementia, severity of bipolar disorder, and number of acute relapses etc) were not available.
Conclusion:Subjects with a previous diagnosis of bipolar disorder may be at increased risk of subsequent dementia, even after controlling for pertinent risk factors.
Comment: Elderly individuals with history of bipolar disorder requires closer monitoring for possible cognitive decline on a regular basis.
Summary of the article:
Wu KY, Chang CM, Liang HY, Wu CS, Chia-Hsuan Wu E, Chen CH, Chau YL, Tsai HJ. Bipolar Disord. 2013. Do15: 787–794