Pseudodementia

Pseudodementia, as the term implies, is a condition that resembles and can be mistaken for dementia. Historically, the term was used to describe reversible deterioration of cognitive function secondary to many conditions, including medical and psychiatric diagnoses. Currently, the term refers primarily to the cognitive impairment seen in patients who have depressive disorders. Recently, it has been replaced by a more descriptive term, namely depression-related cognitive dysfunction. This entry provides an understanding of the term, describes how it differs from dementia, and describes its course and outcome.

Depressive symptoms are quite common in older adults. Population-based studies suggest that nearly 30% of people over 65 years of age show some depressive symptoms. The symptoms of depression in this age group include feelings of sadness; lack of interest in usually enjoyable activities; changes in sleep and appetite; poor energy, motivation, and/or concentration; feelings of hopelessness, worthlessness, and/or excessive guilt; and suicidal thoughts that may be mild (e.g., feeling that life is not worth living) to severe (e.g., intent, plan, and means to end one's life). Many older adults who become depressed can exhibit problems with their cognitive functioning, including memory. C. E. Wells in 1979 distinguished cognitive difficulties associated with depression, termedpseudodementia, from true dementia. Today in doctors' offices, when a patient presents with a new-onset memory complaint, depression is one of the main conditions that needs to be considered in the diagnostic evaluation.

There are several differences between pseudodementia and mild dementia as described by Wells, and some of these differences can be readily elicited in the doctor's office by asking about the patient's medical and psychiatric history. In general, cognitive changes of depression tend to have an abrupt onset and a short course, as opposed to dementia where the cognitive deterioration is gradual. Those patients who primarily have depression often have personal or family histories of depressive symptoms, and these are not common in patients with dementia. Another important difference is in the presentation. Depressed patients are acutely aware of their cognitive dysfunction, may even highlight or exaggerate it, and are distressed by it. On the other hand, demented patients are often unaware of their memory deficits and are often unconcerned about them; if they are somewhat aware, will try to conceal the disability. Typically, demented patients do not seek help from doctors for memory complaints but rather are brought in by family members who have noticed the decline. It is important to note that not all patients with a comparable severity of depression will have cognitive dysfunction; this is a heterogeneous group.

Formal neuropsychological testing carried out by trained psychologists is a more specific way to differentiate between pseudodementia of depression and dementia. Depressed patients are likely to abandon efforts on difficult tests, whereas demented patients will make adequate effort. Depressed patients tend to have inconsistency in test results over time and across a variety of tasks of similar difficulty, whereas demented patients have consistently poor performances. Although both conditions can affect memory, depressed patients are more likely to respond to cueing and do better on memory testing with coaching and feedback, whereas demented patients are not likely to make such gains.

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