The definition of treatment success in depression has changed over the years. In the past, treatment success was regarded as a state of “remission”, in which predominant depressive mood symptoms are reduced to baseline. Over the years, it became increasingly clear that despite achieving a state of conventional “remission”, patients still suffer from significant functional disabilities, which cripples their ability to return fully back to a level of functioning in their work, social or family lives. To this point, all three clinicians stressed that the current definition of treatment success has evolved to be a state of functional recovery, where the patient returns to a level of premorbid functioning.
Importance of treating cognitive symptoms in depression
Functional disability despite successful treatment of mood symptoms can be attributed to residual cognitive symptoms which are not successfully treated. According to studies, cognitive symptoms are present in 94% of all patients in the acute phase of depression, and persist in 44% of patients even in the remission phase1. In a study which measured disability in depressed patients 6 months after hospital discharge, cognitive dysfunction was found to be strongly associated with impaired life functioning2. Furthermore, a recent study highlighted a strong correlation between cognitive improvement and functional improvement in depressed patients3.
Is treatment of depressive symptoms sufficient to address cognitive symptoms?
Even though it is a common view of psychiatrists that treating mood symptoms will improve cognitive symptoms, Prof Baune states that even remitted patients still suffer from cognitive problems, which is a predictor of future relapses. According to him, cognitive symptoms that occur in remission are those involved in psycho-social re-integration which is important for functional recovery. Similarly, Dr. Ang states that in his personal practice, some patients still have residual cognitive symptoms despite improvement in mood symptoms. In Dr. Amer’s clinical practice, he finds that the impact of residual symptoms was actually more pronounced in high functioning individuals.
How do we look out for cognitive symptoms in our patients?
Cognitive symptoms can consist of any symptoms in the four domains of cognition: memory, concentration, executive function (ability to plan and make decisions) and psychomotor speed. According to all three clinicians, patients will not be able to describe symptoms in medical terms, but rather that they did not do as well as in the past, they do not feel quite the same. According to Prof. Baune, clinicians should ask patients to elaborate on their day-to-day activities and use prompting questions to guide them. He also stresses that cognitive symptoms are not just important in the working population, but homemakers as well, who usually have complex schedules and are responsible for taking care of their family, which requires a lot of planning, memory and focus. Dr. Ang also concurs that every individual needs cognitive function in their everyday life, and in Malaysia, cognitive symptoms manifests as difficulty in focusing and carrying out day-to-day tasks. For Dr. Amer, most of his patients are working, so cognitive symptoms come up as slowness in doing their work and a tendency to make mistakes or forget things at work.
How do we assess cognitive symptoms in the clinic?
With the increasing awareness of cognitive symptoms in depression, there has been progress in the diagnosis and awareness of cognitive symptoms. Apart from prompting clinical questions (Prof. Baune: ability to hold a conversation, to understand TV programs and read newspapers. Dr. Ang: concentration as good as before? Able to make decisions as good as before? Difficulties in memory? Dr. Amer: Slowness in performing work? Making mistakes at work?), short assessment tests are available to measure cognitive difficulties. The Digit Symbol Substitution Test (DSST) is a short 90-second test to assess cognition objectively, and the Perceived Deficits Questionnaire for Depression-short (PDQ-5) is a short 5-question subjective self-completed questionnaire, both ideal for the hectic setting of a clinic.
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