Bipolar Disorder Linked to Increased Dementia Risk

A variety of risk factors have been identified in Alzheimer's disease and other types of dementia.

The risk for dementia following major psychiatric syndromes in mid-life is an important research area.

Renate Zilkens and colleagues in Australia recently published an informative study of psychiatric disorders and later dementia risk. This study used a population-based case control methodology.

The key elements in the design of this study included the following:

• Subjects: General population in Western Australia
• Data sources: inpatient, outpatient and emergency medical records along with death records
• Cases: Incident cases of dementia between ages of 65 and 84 years of age
• Controls: Age and sex-matched individuals without incident dementia diagnosis
• Psychiatric diagnoses: medical record diagnoses that were required to be present at least ten years prior to dementia onset
• Statistical analysis: odds ratio using conditional logistic regression

The research group in this study used a variety of models to assess risk based on specific medical and psychiatric disorders.

For simplicity, I have used data from the study to put together the summary graph in this post.

This graph estimates later dementia odds ratios for specific disorders when that disorder is present during the 65-69 year age period.

There is evidence of a strong increase in risk for dementia following bipolar disorder diagnosis (odds ratio 4.71, 95% confidence interval 2.29 to 9.65). Bipolar disorder is the psychiatric disorder with the second highest odds ratio being topped only by schizophrenia with an estimated odds ratio of 12.1. The odds ratio with depression was only slight lower than that associated with a diabetes diagnosis (odds ratio 2.77 vs 3.47). Anxiety disorder had a small but statistically significant increased odds ration for later dementia (odds ratio 1.37, 95% confidence interval 1.14-1.65)

Alcoholism diagnosis by age 65 years of age is also associated with a marked increase in dementia risk (odds ratio 4.14, 95% confidence interval 2.25 to 7.61).

The authors note their findings support the role of psychiatric disorders in contributing to brain vascular abnormalities that can contribute to later cognitive decline. Additionally, they note there is increasing evidence that psychiatric disorders are associated with brain inflammation and immune system dysfunction, areas know to contribute to cognitive decline.

This study is important is suggests at lease five psychiatric disorders need to be considered as potential risk factors for dementia (bipolar disorder plus schizophrenia, depression, anxiety and alcoholism). Adding these risk factors may allow for improvement in detection and prevention efforts.

Additionally, the finding suggest dementia populations may have higher rates of psychiatric disorders. These psychiatric disorders can complicate dementia management and increase the need for psychiatric assessment and consultation in geriatric care settings.

Readers with more interest in this topic can access the free full-text manuscript by clicking on DOI link below.

Follow the author on Twitter @WRY999

Zilkens, R., Bruce, D., Duke, J., Spilsbury, K., & Semmens, J. (2014). Severe Psychiatric Disorders in Mid-Life and Risk of Dementia in Late- Life (Age 65-84 Years): A Population Based Case-Control Study Current Alzheimer Research, 11 (7), 681-693 DOI: 10.2174/1567205011666140812115004