Abstract
The chapter explores the research done so far on neuropsychological deficits in major depressive disorder (MDD). The most prominent deficits have been reported in executive function and the cognitive control networks. These deficits have also been shown to affect various cognitive aspects of a patient, such as metacognitions and emotional regulation. They are also predictors of socio-occupational functioning and of recovering and relapse in patients. This makes it pertinent that these newer treatments for MDD account for these deficits and work on ameliorating them for long-term gains.
TopBackground
MDD is an illness characterized by low mood, loss of interest, difficulty in concentration and easy fatigability. Whilst depressed mood and loss of interest are one of the key features, other cognitive symptoms indicate the severity and character of the episode and contribute to significant functional impairment and impact recovery. Neurocognitive dysfunction is now understood to be central to depression. Deficits are reported mainly in cognitive control functions such as, attention, working memory and other executive functions (EF), which are harbingers of cognitive biases and metacognitive deficits (Shallice, 1996; Vinogradov, Fisher, & De Villers-Sidani, 2012).
Though depression is characterized as an episodic illness, prospective studies have found that most patients have a recurrence (Mueller et al., 1999). Researchers have noted a distinct ruminative form of thinking in patients suffering from MDD. Ruminations are defined as focused attention on symptoms of one’s distress, and on its possible causes and consequences, as opposed to its solutions (Nolen-Hoeksema, 1991). From a neuropsychological perspective rumination may be understood as a result of failure to generate an adaptive response by the executive, top down systems controlling limbic activations (Marchetti et al., 2012; Pisner, 2018).
Key Terms in this Chapter
Metacognition: Metacognition refers to the psychological structures, knowledge, events, and processes that are involved in the control, modification and interpretation of thinking itself. According to recent theorizing, metacognition is an important factor in the development and maintenance of psychological disorder.
Cognitive Control: Cognitive control refers to the ability to override pre-potent responses and to inhibit the processing of irrelevant or previously relevant information. These abilities are related to the functioning of executive control processes, such as inhibition, switching, and updating in working memory.
Emotional Regulation: It is defined as the cognitive processes that may assist individuals in regulating their emotions, and gaining control over these without becoming overwhelmed by them.
Ruminations: Rumination is a maladaptive emotion regulation strategy that is characterized by the tendency to respond to a stressful event with repetitive, perseverative, and negative thinking.