Bipolar Disorder in Later Life

9 Medical Comorbidity in Late-Life Bipolar Disorder

chapter nine Medical Comorbidity in Late-Life Bipolar Disorder helen c. kales, m.d. Mr. P. is an 80-year-old man with a 50-year history of bipolar disorder. The disorder was diagnosed in 1955, when, at age 29, he had his first manic episode. During his younger adulthood he had several manic and depressive episodes, questionable adherence to his prescribed medication, and alcohol abuse. In his fifties, he stopped using alcohol and was maintained on lithium at 1,200 mg/ day, with good results. Then, in 1995, during hospitalization for resection of a benign rectal tumor, Mr. P. became manic after reduction of his lithium dose. Surgery staff noted that he had an elevated mood, labile emotions, and hypersexuality . His mania abated with the resumption of his usual dose of lithium and with the addition of thiothixene; however, one month later he developed symptoms of a severe major depression and received electroconvulsive therapy (ECT) treatments as an inpatient. When Mr. P was discharged he was taking risperidone, which was tapered and discontinued while he was an outpatient; he eventually began taking lithium again, at 900 mg/day. Mr. P. developed non-insulin-dependent diabetes mellitus in 1997, but he was psychiatrically stable until 1998, when he had an episode of lithium toxicity precipitated by addition of an angiotensin-converting enzyme (ACE) inhibitor to his antihypertensive regimen. Mr. P. restarted lithium at a dose of 600 mg/ day, and his mood remained stable. In 2001 he developed memory problems, and following a cognitive workup that included magnetic resonance imaging (MRI) and neuropsychological testing, he was diagnosed with vascular dementia in the context of his diabetes. Mr. P. continued to live in a senior apartment, but because of his memory problems, he began to have difficulty adhering to his medication regimen. This resulted in an episode of severe mania with psychosis and three psychiatric hospitalizations. Because his difficulties with memory were contributing to his mood destabilization, and given the lack of family involvement, Mr. P. was eventually placed in a community nursing home. Medical comorbidity frequently accompanies late-life bipolar disorder and often may complicate its treatment and course. The case of Mr. P. illustrates several themes to be discussed in this chapter: (1) common comorbidities in late-life bipolar disorder, including the connection between late-life mania and dementia syndromes ; (2) medical disorders related to the pharmacological treatment of bipolar disorder; (3) medication interactions and changes in medication dosing required to address comorbidities; and (4) changes in care management necessitated by the cooccurrence of bipolar disorder and medical illnesses. Medical, predominantly neurological, disorders also cause secondary or newonset mania in late life. In these cases, the psychiatric disorder is not comorbid with the medical disorder but a manifestation of it (Krishnan 2005). Secondary mania is thus not a focus of this chapter; it is discussed in detail in chapter 4. common comorbidities in late-life bipolar disorder Medical illnesses accompany bipolar disorder at rates greater than that predicted by chance. In one study, 20% of older patients with bipolar disorder had seven or more co-occurring medical illnesses, a higher prevalence than in patients with schizophrenia (Brown 2001). Comorbidity takes on special significance in bipolar disorder . This disorder is among the illnesses associated with the largest suicide risk in older adults, and a study found strong associations between the cumulative number of illnesses and the estimated relative risk of suicide (Juurlink et al. 2004). In the latter study, patients with five illnesses were found to have a fivefold increase in suicide risk. As Krishnan (2005) noted, it is often not clear whether medical disorders among individuals with bipolar disorder are truly comorbid or are a consequence of treatment , or a combination of both. Diabetes A good example of the possibly bidirectional relation between bipolar disorder and some medical illnesses in late life is the link between bipolar illness, diabetes, and obesity (McElroy et al. 2002). The prevalence of diabetes in persons with bipom e d i c a l c o m o r b i d i t y i n l a t e - l i f e b i p o l a r d i s o r d e r 163 lar disorder is significantly higher than that in the general population: the prevalence was found to be between 12% and 26% of mixed-age samples of patients...