J Affect Disord. 2012 Jul 23;
Authors: Maeshima H, Baba H, Nakano Y, Satomura E, Namekawa Y, Takebayashi N, Suzuki T, Mimura M, Arai H
Abstract
BACKGROUND: Depression may increase the risk of developing Alzheimer’s disease. Large cohort studies have shown that recurrent depression is associated with a risk of developing dementia. Other studies have documented smaller hippocampal volume in patients with recurrent depression. It is speculative that a greater risk of developing dementia may result from a higher number of previous depressive episodes. This study compared patients with recurrent and single-episode depression in the remitted stage, and healthy controls to elucidate the impact of the number of depressive episodes on memory.
METHODS: Logical memory and visual reproduction subtests of the Wechsler Memory Scale-Revised were given to 68 patients with major depressive disorder (MDD) (30 patients with a single episode and residual 38 patients with recurrent multiple episodes) and 57 healthy controls. The patients with MDD received memory assessment at the time of initial remission and at the follow-up period 3 years after remission.
RESULTS: At the time of initial remission, scores of both logical memory and visual reproduction subtests were significantly lower in both patient groups compared with healthy controls. At follow-up, memory dysfunction of the single-episode group disappeared, whereas scores in the recurrent group remained significantly lower than those of the single-episode group and controls.
LIMITATIONS: All patients in the present study were on antidepressant medications.
CONCLUSIONS: Patients with recurrent MDD with multiple depressive episodes showed residual memory dysfunction even after 3 years of remission. Persistence of memory deficits in the recurrent depression may be a risk factor for developing dementia.
PMID: 22832170
—
A significant limitation of this study is the definition used for “remission”. On the HAM-D scale, for example, “remission” is often defined as having a score of 0 to 7. The problem is that at least half of patients in such a “remission” do not feel they are in remission. Additionally, a score under 7 can still have serious symptoms of depression such as full-blown psychosis (a score of 4) yet would be considered “in remission”.
Ideally and from a patient expectation view, remission should mean not only being symptom-free but that the underlying pathophysiology of depression has been successfully addressed so that wellness has been restored and future recurrence of illness is minimized.
Since depression has a highly complex pathophysiology – with problems often involving environmental-social-psychological issues, neurological, endocrine, and immunologic problems, and metabolic-nutritional problems, it is not surprising that a single treatment such as antidepressant medication treatment does not fully address the pathophysiology of illness. And thus, the patient is likely to have a recurrent episode and despite treatment remains ill.
The persistent residual memory deficit in recurrent major depressive disorder is a sign that the full pathophysiology of the illness was not addressed by treatment. Such a patient is obviously susceptible to a recurrent episode of major depression.