Depressive pseudodementia: a suggested diagnostic profile

Severe cognitive and memory impairments often occur during episodes of depression, making it difficult to differentiate true dementia from depressive pseudodementia. The dexamethasone suppression test (DST) and the computerized tomography of the brain (CT scan) may aid in this problem. Eleven patients were assessed with the Hamilton Depression Rating Scale (HDRS), a Dementia Scale (DS), the overnight DST, and CT scans. Clinicians and raters were blind to DST results. All patients initially had high DS scores. These changed in most patients following antidepressant treatments. This study suggests a profile for the diagnosis of pseudodementia. Patients with cognitive impairment, dysphoric mood, abnormal response to the DST, and normal CT scan tend to have depressive pseudodementia. Patients with the first three features but with an abnormal CT scan likely have depression and structural brain pathology. Both groups respond to antidepressant treatments, although the latter continued to have some cognitive dysfunction during euthymia. A third group, the "true" dementia patients, may have abnormal CT scans and a normal DST response but larger samples are needed for confirmation.