High risk of silent stroke in older bipolar patients with typical-onset age

Older patients with bipolar disorder (BD) are at a high risk of stroke. Silent stroke could be neglected in BD patients after middle age, particularly in those with illness onset at the young age. Therefore, we investigated the morbidity and related factors for stroke in older BD patients with typical-onset age.

Older patients with bipolar I disorder (age > 50 years) and their illness onset prior to the age of 40 years were recruited. After whole-brain magnetic resonance imaging was conducted, the patients were divided into stroke and non-stroke groups. Clinical data were obtained by reviewing all available medical records and directly interviewing the patients along with their reliable family members.

We recruited 62 patients with a mean age of 60.4 years and illness onset at the mean age of 28.4 years. Cerebral infarction or old stroke was observed in 24 (38.7%) patients, including 22 without any reported clinical history of stroke. That is, silent stroke (n = 22) was detected in 36.7% of 60 patients without clinical history of stroke. The stroke group had significantly higher mean numbers of lifetime mood episodes (P = 0.006) than the non-stroke one. Logistic regression analysis showed that 10 or more prior mood episodes (odds ratio = 3.43, 95% confidence interval = 1.12-10.47, P < 0·04) was significantly associated with the occurrence of stroke. The two study groups did not exhibit any other differences in demographic and clinical variables, such as age, laboratory or physical measurements during the last acute psychiatric hospitalisation, body mass index, and substance use problems and concurrent medical diseases.

High morbidity of stroke, particularly silent stroke, could be found in older bipolar patients with typical-onset age. In addition to traditional risk factors, the number of recurrent mood episodes in a lifetime may increase the risk of stroke in older BD patients.