Almost all domains of cognition are affected in depression: memory, reaction time or processing speed, executive function and the strategic planning of future action. Deficits can be subtle, but they are found both in the acute phase and in remission. And even the subtle deficits play out in poorer work and day-to-day functioning.

Assessment of a problem is a step towards its solution. Full neuropsychological testing has its place, but we can develop short and more easily applied screening tools, and even those based on patient self-report, which cover both objective and subjective cognitive functioning. Such tools need to be validated in patients with depression, of course, and validated against functional outcomes. But they can then be used in clinical studies.

Cognition involves highly complex systems in the brain, so evaluation of biomarkers is difficult. But there are conditions associated with poor cognitive function where markers of inflammation seem to relate to impairment. And there is some evidence this is true also in depression.

In overall treatment, there is evidence that the most effective approach is a combination of pharmacological and non-pharmacological therapies. Cognition can improve following a general improvement in depression.

In the non-pharmacological field, cognitive training and remediation therapy can improve function in schizophrenia and bipolar disorder; and they may also do this in depression. In terms of pharmacological intervention, there is growing evidence that antidepressants may have effects on cognitive function in depression.

There is much work still to come. But the emphasis on cognitive dysfunction is already influencing daily clinical practice. People are starting to detect cognitive problems in depression and are wanting to do something about them.

Almost all domains of cognition are affected in depression: memory, reaction time or processing speed, executive function and the strategic planning of future action. Deficits can be subtle, but they are found both in the acute phase and in remission. And even the subtle deficits play out in poorer work and day-to-day functioning.