Questions have been raised about whether poor performance on memory tasks by individuals with major depressive disorder (MDD) might be the result of poor or variable effort or disease-related disruption of neural circuits supporting memory functions. The present study examined performance on a measure of task engagement and on an auditory memory task among 45 patients with MDD (M age = 47.82, SD = 19.55) relative to 32 healthy controls (HC; M age = 51.03, SD = 22.09). One-hundred percent of HC and MDD volunteers performed above the threshold for adequate effort on a formal measure of task engagement. The MDD subjects performed significantly more poorly than the HC subjects on an auditory learning and memory test. The present results suggest that auditory memory difficulties do occur among those with MDD and that decrements in performance in this group may be related to factors other than lack of effort.

Background

Peginterferon and ribavirin treatment of chronic hepatitis C (CHC) is frequently associated with dose-limiting neuropsychiatric toxicity. The purpose of this study is to determine whether prolonged administration of low-dose peginterferon-α2a is associated with an increase in the rate and severity of depression compared to untreated controls.

Methods

129 non-responders to full dose peginterferon and ribavirin treatment were randomized to low dose maintenance treatment with peginterferon-α2a 90 ug/wk or no treatment for 3.5 years. Depression was assessed using the Beck Depression inventory (BDI-II) and the Composite International Diagnostic Interview (CIDI) at baseline and at 12, 24, 36, and 48 months. “Clinical depression” was defined as BDI-II ≥11 and/or meeting DSM-IV criteria for major depression on the CIDI. Serial cortisol and serotonin plasma concentrations were obtained in a subgroup of patients.

Results

Rates of clinical depression did not significantly differ over time or between treatment groups. Baseline clinical depression was the only significant predictor of clinical depression over time (p<0.001). Rates of clinical depression were also significantly higher in patients experiencing liver disease progression (p=0.016). Antidepressant use did not significantly differ between groups. Adjusted whole blood serotonin levels dropped significantly over time (p=0.04), but there was no group by time effect.

Limitations

Lack of significant group differences in antidepressant use does not completely preclude significant mood changes masked by antidepressants. Results may differ in treatment-naïve CHC patients or in those receiving full dose peginterferon.

Conclusions

Prolonged low-dose peginterferon-α2a treatment is not associated with an increase in the frequency or severity of clinical depression in prior non-responder patients with chronic hepatitis C.

The most extensively described pathological abnormality in Parkinson's disease (PD) is loss of dopaminergic neurons in the substantia nigra pars compacta and the ventral tegmental area, with degeneration of their striatal terminals. Because of the intimate connections between the striatum and the frontal lobes, individuals with PD often demonstrate impairments on those tasks relying on the prefrontal cortex (e.g., tests of executive functioning). Source memory, or memory for context, is believed to rely on the prefrontal cortex and has been previously associated with executive functioning performance, although it has received little attention in the PD literature. Executive functioning and source memory were measured in a group of nondemented PD patients and healthy control participants. Within the PD group, an anti-Parkinson's medication withdrawal manipulation was used to examine whether source memory was affected by phasic changes in dopamine levels. Compared to healthy control participants, PD patients were impaired in source memory (both on- and off-medication) and on a composite measure of executive functioning. Within the PD group, medication administration improved motor performance but did not have a significant effect on source memory.