Drugs that target glutamate neuronal transmission, such as memantine, offer a novel approach to the treatment of late-life depression, which is frequently comorbid with cognitive impairment. The results of our recently published double-blind, randomized, placebo-controlled trial of escitalopram or escitalopram/memantine in late-life depression with subjective memory complaints (NCT01902004) indicated no differences between treatments in depression remission, but additional benefits in cognition at 12-month follow-up with combination treatment. To identify pathways and biological functions uniquely induced by combination treatment that may explain cognitive improvements, we generated transcriptional profiles of remission compared with non-remission from whole blood samples. Remitters to escitalopram compared with escitalopram/memantine combination treatment display unique patterns of gene expression at baseline and 6 months after treatment initiation. Functional enrichment analysis demonstrates that escitalopram-based remission associates to functions related to cellular proliferation, apoptosis, and inflammatory response. Escitalopram/memantine-based remission, however, is characterized by processes related to cellular clearance, metabolism, and cytoskeletal dynamics. Both treatments modulate inflammatory responses, albeit via different effector pathways. Additional research is needed to understand the implications of these results in explaining the observed superior effects of combination treatment on cognition observed with prolonged treatment.

Objective

Geriatric depression is difficult to treat and frequently accompanied by cognitive complaints that increase risk for dementia. New treatment strategies targeting both depression and cognition are urgently needed.

Methods

We conducted a 6-month double-blind placebo-controlled trial to assess the efficacy and tolerability of escitalopram + memantine (ESC/MEM) compared to escitalopram + placebo (ESC/PBO) for improving mood and cognitive functioning in depressed older adults with subjective memory complaints (NCT01902004). Primary outcome was change in depression as assessed by the HAM-D post-treatment (at 6 months). Remission was defined as HAM-D ≤6; naturalistic follow-up continued until 12 months.

Results

Of the 95 randomized participants, 62 completed the 6-month assessment. Dropout and tolerability did not differ between groups. Mean daily escitalopram dose was 11.1 mg (SD = 3.7; range: 5-20 mg). Mean daily memantine dose was 19.3 mg (SD = 2.6; range 10-20 mg). Remission rate within ESC/MEM was 45.8% and 47.9%, compared to 38.3% and 31.9% in ESC/PBO, at 3 and 6 months, respectively (χ²(1) = 2.0, p = 0.15). Both groups improved significantly on the HAM-D at 3, 6, and 12 months, with no observed between-group differences. ESC/MEM demonstrated greater improvement in delayed recall (F(2,82) = 4.3, p = 0.02) and executive functioning (F(2,82) = 5.1, p = 0.01) at 12 months compared to ESC/PBO.

Conclusions

The combination of memantine with escitalopram was well tolerated and as effective as escitalopram and placebo in improving depression using HAM-D. Combination memantine and escitalopram was significantly more effective than escitalopram and placebo in improving cognitive outcomes at 12 months. Future reports will address the role of biomarkers of aging in treatment response.

Objective

Sensory overresponsivity (SOR), an atypical negative reaction to sensory stimuli, is highly prevalent in autism spectrum disorder (ASD). Previous work has related SOR to increased brain response in sensory-limbic regions. This study investigated where these atypical responses fall in three fundamental stages of sensory processing: arousal (i.e., initial response), habituation (i.e., change in response over time), and generalization of response to novel stimuli. Different areas of atypical response would require distinct intervention approaches.

Methods

Functional MRI was used to examine these patterns of neural habituation to two sets of similar mildly aversive auditory and tactile stimuli in 42 high-functioning children and adolescents with ASD (21 with high levels of SOR and 21 with low levels of SOR) and 27 age-matched typically developing youths (ages 8-17). The relationship between SOR and change in amygdala-prefrontal functional connectivity across the sensory stimulation was also examined.

Results

Across repeated sensory stimulation, high-SOR participants with ASD showed reduced ability to maintain habituation in the amygdala and relevant sensory cortices and to maintain inhibition of irrelevant sensory cortices. These results indicate that sensory habituation is a dynamic, time-varying process dependent on sustained regulation across time, which is a particular deficit in high-SOR participants with ASD. However, low-SOR participants with ASD also showed distinct, nontypical neural response patterns, including reduced responsiveness to novel but similar stimuli and increases in prefrontal-amygdala regulation across the sensory exposure.

Conclusions

The results suggest that all children with autism have atypical brain responses to sensory stimuli, but whether they express atypical behavioral responses depends on top-down regulatory mechanisms. Results are discussed in terms of targeted intervention approaches.