Latimer: Importance of cognitive deficits in psychiatric disorders

Much more research is needed on this aspect of psychiatric treatment and assessment.

Most of the time, attention and treatment in mental illness focus on obvious primary symptoms such as mood, anxiety or psychosis.  However, another important aspect of these conditions involves cognitive function and it deserves a much closer look.

Typically, treatment of psychiatric disorders focuses on hallmark presenting symptoms such as depressed mood, anxiety, delusions, mania or hallucinations. We know how to treat these and most of the time can reduce or eliminate these symptoms in the short term. Once this has been done, however, the patient often reports that although they are much improved in these areas, they are still having problems with such things as memory, learning new information, finding words, staying focused or some other aspect of what we call cognitive functioning.

We are not very good at measuring cognitive function or treating it when it is impaired. It is a complicated problem because we almost never have a pre-illness baseline measure of cognitive ability to work with. As a result, when we measure it post-illness, we don’t know how it compares with functioning at its best.

Often a patient reports impaired cognitive functioning, but when it is measured it appears to be average. Without a history we don’t know how their normal ability compared to the average for the test norms. It could be that their functioning has declined from an earlier level or that it has been affected in some way we are not identifying with our crude measurements.

In other cases we can clearly see a decline in cognitive functioning, but we can’t see why the decline has occurred. An example, of this is ‘pseudodementia’. I had a patient recently who was recovering from a serious bipolar depression and having significant memory problems.

In this case, we did the same kind of testing we use for dementia patients and these showed the individual to be suffering moderate impairment indistinguishable from what would be seen in Alzheimer’s disease. It was severe enough that I thought the person may soon be unable to look after themself.

I continued to modify the bipolar medications and eventually, and rather abruptly, the cognitive functioning returned to normal. It seems to be fairly common for cognitive impairment and mood to improve at different rates.

In other cases we see patients who have suffered a head injury but who also are depressed or suffering PTSD. Cognitive testing shows impairment but often it is not clear whether the problems are related to the head injury or to the mood and anxiety disorders that have come on at the same time.  This can have implications for compensation related to the accident as well as for the most appropriate treatment.

Our assessment of the problems with thinking (cognitive dysfunction) can be complicated by the presence of possible effects of medication, lack of sleep, depression, anxiety, head injury or pre-existing conditions such as ADHD or learning disabilities.

Much more research is needed on this aspect of psychiatric treatment and assessment. It would be very helpful it we had easy to use, generally accepted, inexpensive methods with which to assess cognitive functioning at multiple points in time.  There are some methods in existence but they are generally not covered by provincial health plans and are not readily available to most patients.

Paul Latimer is a psychiatrist and president of Okanagan Clinical Trials.