To be “in default” is commonly defined as “failing to meet an obligation or to fulfill a responsibility or goal.” The term “default” is also synonymous with “insufficient performance.” If you have experienced such mental states as “having brain fog” or “having no motivation” or “being unable to get anything done,” you were stuck in the default mode. In 2001, neuroscientist Marcus Raichle, M.D., proposed that the brain’s Default Mode Network (DMN) and the Task Positive Network (TPN) are two critical networks involved in goal-directed behaviors, emotional regulation, and executive functions, such as problem-solving, decision-making, memory, organizational skills, and attention span. The Default Mode Network is a brain region which has been determined to have lower levels of activity when an individual needs to exhibit attention and conscious effort toward completing tasks. This network consists of the medial prefrontal cortex, the precuneus, and the posterior cingulate cortex, which are responsible for self-reflection, memory, learning, and emotional regulation, and the medial prefrontal cortex sends signals to the hippocampus, which is the brain’s primary memory center. Dr. Raichle proposed that the brain’s Task Positive Network (also called the salient network) mobilizes when an individual must perform necessary tasks, complete projects, study for exams, and fulfill daily personal responsibilities, yet those who are prone to the default mode can experience great difficulty with accomplishing these tasks. The low motivation and poor focus caused by the Default Mode Network have been found to be more prominent in those with Attention Deficit Hyperactivity Disorder (ADHD), Post-Traumatic Stress Disorder (PTSD) and Generalized Anxiety Disorder (GAD). Individuals with these disorders struggle with getting stuck in the default mode, to the point of feeling “mentally paralyzed” and being unable to activate the necessary cognitive and behavioral skills for accomplishing their goals.
Research on dysregulation in the Default Mode Network has found that individuals with ADHD have very high incidences of distractibility during work, academic, and social activities. Researchers attribute this occurrence to weak connectivity between the prefrontal cortex and the brain’s memory structure, the hippocampus, causing a disconnect between what the individual sees or hears and what the individual retains through the hippocampal processes. Furthermore, the Default Mode Network keeps the brain in a resting, unfocused state and challenges the Task Positive Network when the ADHD individual needs to stay focused, causing a sense of dissociation from what needs to be accomplished in the present situation. Due to the brain’s low level of reaction to external stimuli, an individual with ADHD may start a project but is distracted by almost any stimulus, such as one’s text message alert sounds, one’s dishes which need to be done, or one’s phone which triggers the desire to scroll through social media posts. Another common ADHD symptom is “reduced task-switching ability,” referring to frequent difficulties switching from “default mode” into “work mode.” Furthermore, an overactive Default Mode Network impacts the basal ganglia region, which is responsible for motor skills and alertness, resulting in an ADHD individual’s difficulty with behavioral tasks, such as organizing one’s work space or getting oneself to an appointment on time.
Even when the ADHD individual is trying to focus, there will be random lapses in attention and memory which have been associated with the Default Mode Network. A state of default shows in brain scans (MRI’s) as resting states, which cause the poor connectivity from the executive functioning structures to the hippocampus. This explains why working memory deficits and difficulty prioritizing important information are commonly observed in those with ADHD. The linkage between working memory deficits and attentional fluctuations causes those with ADHD to have a more difficult time with goal-directed tasks and to dissociate by daydreaming or just thinking about random, unrelated information. Communicating in the workplace may provoke much anxiety, due to frequent forgetfulness of deadlines and instructions or ideas getting mixed up when speaking to colleagues or supervisors. All of these work or academic experiences can cause intense shame.
PTSD and GAD have some overlapping symptoms with ADHD, such as forgetfulness, thought disorganization in work, academic, and social settings, poor short-term memory, and frequent dissociation when needing to focus. In those with PTSD and GAD, default mode network dysfunction may underlie the tendency to ruminate over the past or to have intrusive worries and fears about the future. While ADHD individuals tend to be impulsive and “mind-wandering,” those with PTSD or GAD tend to exhibit the “freeze” response when confronted with a task, especially one which is uninteresting or challenging. However, attention deficits and trauma/stress triggers can both cause dysfunctions in emotional regulation, coping skills, learning, and memory. In PTSD and GAD, the Medial Prefrontal Cortex loses control over the hippocampus, resulting in ruminating or hyper-focusing on self-defeating thoughts, past traumatic experiences, and/or fears about inadequacy and failure. Those with PTSD and GAD have been found to have impaired emotional and behavioral regulation, due to poor connectivity between the executive functioning structures and the amygdala, which is responsible for managing fear and aggression. Furthermore, due to the poor connectivity from the executive functioning structures to the hippocampus, those with PTSD and GAD tend to experience past traumatic memories as if they are occurring in the present, thus the trauma remains unprocessed. Researchers have also attributed this poor connectivity to avoidance/numbing symptoms, which include avoidance of thoughts and feelings about the trauma and avoidance of reminders of the trauma.
In ADHD, PTSD, and GAD, distractibility and dissociation during important tasks are caused by decreased activity in the hippocampus, the brain’s memory center. The default state of the medial prefrontal cortex can take the individual away from the present moment’s necessary thought processes and intentional actions. The frustrating and embarrassing mental fugue caused by getting stuck in the default mode occurs randomly and increases when the individual is dealing with greater stress. Researchers have become increasingly interested in the role of the Default Mode Network in lower levels of work and academic performance. Many studies have correlated neurological dysfunctions with attention and learning deficits or trauma-related anxiety symptoms. ADHD, PTSD, and GAD are three diagnoses which have often been minimized or misunderstood by medical and psychological professionals. Therefore, the role of the Default Mode Network in these disorders requires more research and should be incorporated in trainings for mental health professionals. The treatment of an overactive Default Mode Network must be multi-modal, such as medication with Mindfulness-Based Stress Reduction and Cognitive Behavioral Therapy.
