Neuroplasticity in cognitive and psychological mechanisms of depression: an integrative model

Abstract

Chronic stress and depressive-like behaviors in basic neuroscience research have been associated with impairments of neuroplasticity, such as neuronal atrophy and synaptic loss in the medial prefrontal cortex (mPFC) and hippocampus. The current review presents a novel integrative model of neuroplasticity as a multi-domain neurobiological, cognitive, and psychological construct relevant in depression and other related disorders of negative affect (e.g., anxiety). We delineate a working conceptual model in which synaptic plasticity deficits described in animal models are integrated and conceptually linked with human patient findings from cognitive science and clinical psychology. We review relevant reports including neuroimaging findings (e.g., decreased functional connectivity in prefrontal-limbic circuits), cognitive deficits (e.g., executive function and memory impairments), affective information processing patterns (e.g., rigid, negative biases in attention, memory, interpretations, and self-associations), and patient-reported symptoms (perseverative, inflexible thought patterns; inflexible and maladaptive behaviors). Finally, we incorporate discussion of integrative research methods capable of building additional direct empirical support, including using rapid-acting treatments (e.g., ketamine) as a means to test this integrative model by attempting to simultaneously reverse these deficits across levels of analysis.

Figure 1:

Regions with prominent neuroplasticity deficits in animal models of depression^, (in green) and functionally interconnected regions within a cortico-mesolimbic circuit relevant to mood regulation (blue). Some proposed functions of these regions with relevance in our integrative model are highlighted. “Medial prefrontal cortex (PFC),” as implicated in animal models, includes a number of subdivisions implicated in human depression including subgenual anterior cingulate cortex (ACC) and ventro- and dorso-medial PFC areas. Dashed lines represent primary hypothesized impairments in prefrontal cortex connectivity and top-down regulation of limbic regions, resulting in impairments in behavioral and cognitive flexibility across levels of analysis.