Elderly depression is commonly accompanied by one or more co-morbidities. That is, older people with depression are likely to have one or more other illnesses. Polypharmacy, the prescribing and dispensing of several different medicines to an individual patient, is an inevitable result of comorbidity.

Polypharmacy can have an impact on the treatment of elderly depression in many ways. The patient may experience interactions between different medications, prescribed for either the same, or different, disorders. An antidepressant may be one of these medications or it may be left out for fear of interactions, leaving elderly depression untreated.

Various co-morbidities tend to be found with elderly depression such as

• Heart disease
• Cerebrovascular disease, stroke
• Parkinson’s disease
• Diabetes
• Pancreatic and some other cancers
• Dementia, including Alzheimer’s disease
• Insomnia
• Pain, including chronic arthritis

Elderly depression may be the cause or the consequence of these comorbidities. Little is known of the real links between elderly depression and its common comorbidities. However, we do know that 20% of heart patients are at risk of depression and patients with depression have an 81% higher risk of heart disease. Similar interactions, also deserving of further research, are found between type 2 diabetes and depression.

Comorbidity leads to polypharmacy. A 2006 survey showed that 28% of non-institutionalized adults aged 65 or more had used five or more prescription drugs in the last week and the trend has been an increasing one since 2000. The older you get, the more complex your meds become. Another survey, from Sweden, showed that 58% of men and 61% of women aged 90 plus were regularly using four or more prescription medications.

A significant number of those patients taking several medications have depression - but whether this is actually aggravated by polypharmacy is unclear. We do know that antidepressants interact with many other drugs yet there is often a failure to realise how risky this can be for older depressed patients (maybe because the elderly are rarely included in the clinical trials that generate this information). Concerns about comorbidity and polypharmacy highlight the need for a new approach to treating elderly depression. It may be that the disease management approach, which has had some success with heart and lung disease, could really help in elderly depression. Organized team work in primary care and combining psychotherapy with antidepressants could be important elements of such management and we will discuss this in the next article of this series.

Selected references:

Psychiatric Times 25 [14] 1^st December 2008
Patterns of medication use in the United States in 2006 – a Report from the Slone Survey, Slone Epidemiology Center, Boston University
Halling A, Fridh G and Ovhed A Validating the Johns Hopkins ACG case mix of the elderly in Swedish primary health care, BMC Public Health 2006;6:171

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