Pao-Huan Chen1,2, Hsing-Cheng Liu2,3, Mong-Liang Lu2,4, Chun-Hsin Chen2,4, Ching-Jui Chang5, Wei-Che Chiu5, I-Wen Sun6, Shen-Ing Liu6, Shang-Ying Tsai1,2, Chih-Chiang Chiu2,3, Robert Stewart7,8. 1. Department of Psychiatry, Taipei Medical University Hospital, Taipei, Taiwan. 2. Department of Psychiatry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. 3. Department of Psychiatry, Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan. 4. Department of Psychiatry, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan. 5. Department of Psychiatry, Cathay General Hospital, Taipei, Taiwan. 6. Department of Psychiatry, Mackay Memorial Hospital, Taipei, Taiwan. 7. King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK. 8. South London and Maudsley NHS Foundation Trust, London, UK.
Abstract
OBJECTIVES: The association between older-age bipolar disorder and cognitive impairments may be mediated by vascular burden. The aim of the study was to examine the difference of cognitive function between older people with late-onset bipolar disorder (LOBD) and early-onset bipolar disorder (EOBD) by considering rigorous vascular risk burden evaluation, comprehensive cognitive tests, and relevant biochemistry data. METHODS: We recruited 95 outpatients aged over 55 with a DSM-IV-TR diagnosis of bipolar I disorder. Fifty had LOBD, defined by age of onset after 40. Cognitive function was evaluated through a battery of tests assessing verbal memory, attention/speed, visuospatial function, verbal fluency, and cognitive flexibility. Vascular risk assessments included individual disorders, 10-year Framingham cardiovascular risk scores, and serum levels of homocysteine, vitamin B12, folate, and triiodothyronine. RESULTS: No differences were observed between LOBD and EOBD on any cognitive test after adjusting for potential confounders. In addition to age and educational years, multiple linear regression analyses indicated significantly negative associations between serum homocysteine levels and cognitive performances in attention, psychomotor speed, verbal memory, and executive function. CONCLUSIONS: Among older people with bipolar disorder, LOBD is not associated with more cognitive dysfunction in this study. However, higher serum homocysteine levels were significantly associated with worse cognitive performance in this particular group. Clinicians therefore have to pay attention to the cognitive function in older bipolar patients with higher levels of homocysteine.
OBJECTIVES: The association between older-age bipolar disorder and cognitive impairments may be mediated by vascular burden. The aim of the study was to examine the difference of cognitive function between older people with late-onset bipolar disorder (LOBD) and early-onset bipolar disorder (EOBD) by considering rigorous vascular risk burden evaluation, comprehensive cognitive tests, and relevant biochemistry data. METHODS: We recruited 95 outpatients aged over 55 with a DSM-IV-TR diagnosis of bipolar I disorder. Fifty had LOBD, defined by age of onset after 40. Cognitive function was evaluated through a battery of tests assessing verbal memory, attention/speed, visuospatial function, verbal fluency, and cognitive flexibility. Vascular risk assessments included individual disorders, 10-year Framingham cardiovascular risk scores, and serum levels of homocysteine, vitamin B12, folate, and triiodothyronine. RESULTS: No differences were observed between LOBD and EOBD on any cognitive test after adjusting for potential confounders. In addition to age and educational years, multiple linear regression analyses indicated significantly negative associations between serum homocysteine levels and cognitive performances in attention, psychomotor speed, verbal memory, and executive function. CONCLUSIONS: Among older people with bipolar disorder, LOBD is not associated with more cognitive dysfunction in this study. However, higher serum homocysteine levels were significantly associated with worse cognitive performance in this particular group. Clinicians therefore have to pay attention to the cognitive function in older bipolarpatients with higher levels of homocysteine.