How best to tackle a challenging core feature of MDD.
Cognitive behavioral therapy (CBT) has become a popular psychological therapy for MDD, but little is known about its impact on neuropsychological functioning-a challenging core feature of MDD.
A multicenter team of researchers from New Zealand examined the impact of CBT and schema therapy on neuropsychological functioning in patients with MDD and found that despite significant improvement in mood, impairment in neuropsychological functioning persisted.1 The results confirm earlier research that showed a significant degree of neuropsychological impairment persists after mood symptoms resolve in patients with MDD.2
The study included 69 outpatients with MDD, who were randomized to a yearlong course of either CBT or schema therapy, and 58 healthy controls. Participants completed mood ratings, neuropsychological measures, and measures of emotional processing at baseline and after 16 weeks; they were medication-free throughout the study and in the lead-up to it.
The researchers expected to at least see gains in verbal learning and memory, if not attention and executive functioning, based on previous research on the impact of therapeutic interventions for MDD on neuropsychological functioning.3 Neuropsychological assessments, which included a total of 35 measures, targeted verbal learning and memory, visuospatial learning and memory, and facial emotion processing.
Although mean depression rating scores in the patients fell by more than 50% after 16 weeks of psychological therapy, no convincing evidence of improvement in neuropsychological functioning was detected and no change in emotional processing was seen.
Performance regarding attention and executive functioning (Controlled Oral Word Association Test), digit span, spatial recognition memory, and several measures of verbal learning and memory significantly correlated with baseline severity of depressive symptoms (P < .01), but minimal to no change was seen at 16-weeks’ follow-up.
When the impact of CBT on neuropsychological functioning was compared with that of schema therapy, only a measure of auditory verbal learning (Consonant Vowel Consonant Auditory Verbal Learning Test) significantly differed: performance in the schema therapy group improved and that of the CBT group worsened after 16 weeks (P = .02).
The researchers concluded that although CBT and schema therapy improve depressive symptoms, they do not affect neuropsychological functioning-at least not in the short term. As for pharmaceutical therapy, definitive information on the effects of antidepressants on neuropsychological functioning in patients with MDD is not available, the authors emphasized.
They did point out, however, that several studies suggest that newer psychological methods that include a cognitive functioning component, such as meta-cognitive therapy, hold promise for better outcomes in relation to neurological functioning.
1. Porter RJ, Bourke C, Carter JD, et al. No change in neuropsychological dysfunction or emotional processing during treatment of major depression with cognitive behavior therapy or schema therapy. Psychol Med. 2016;46:393-404.
2. Bortolato B, Carvalho AF, McIntyre RS. Cognitive dysfunction in major depressive disorder: a state-of-the-art clinical review. CNS Neurol Disord Drug Targets. 2014;13:1804-1818.
3. Douglas KM, Porter RJ. Longitudinal assessment of neuropsychological function in major depression. Aust N Z J Psychiatry. 2009;43:1105-1117.