Distinguishing depression from dementia in later life: a pilot study employing the Emotional Stroop task

In later life, cognitive impairment is common in depression often making it difficult to distinguish a dementing illness from depression. We examined whether people with depression could be differentiated from those with dementia on their performance on a task that examines attentional bias to depression related material.

Twelve older adults who fulfilled DSM-IV criteria for major depression were compared with 12 people with Alzheimer's Disease (AD) and 12 age matched controls on a test of cognitive biases: the Emotional Stroop task. In this task participants were presented with words written in different coloured inks, and they had to name the colour the word was written in. Four types of material were presented-neutral, positive, and negative emotion words as well as a condition of meaningless symbols.

People with depression and those with AD were both slower than the controls on the task generally. However, the depressed group alone showed a statistically significant and specific increase in response time when colour naming the negative emotion words. The other two groups did not demonstrate such a pattern and colour named neutral, positive and negative words equally quickly.

The biased processing of depression related material may have a valuable role in distinguishing depression from dementia in later life. Although the Emotional Stroop in its present form is not sufficient for such a purpose. Furthermore, the demonstration that older adults with depression exhibit such biases helps provide a theoretical basis for the application of cognitive behavioural treatments with older adults.