Lost & Disordered

The articles by Berman et al. (2011), Sayette, Reichle, & Schooler (2009), Manly et al. (2003), and Bonnelle et al. (2011) which will be discussed in this post, examine subjects with disordered attention.  These studies were particularly interesting to me as I have done a lot of work focusing on the study of clinical psychology.  Therefore, as my knowledge in mind wandering has progressed throughout this semester, I have been constantly questioning how this mind wandering research relates to those with certain psychological disorders (refer to the Clinical Corners found in past posts).

The cyclical nature of depression is characterized by one’s increased rumination, thus leading to increased salience of negative information.  It has already been established that the default network is engaged during mind wandering episodes (Mason et al., 2007), however the study by Berman et al. (2011) suggests that this activation is different for those diagnosed with depression compared to healthy subjects.  By studying this effect in those diagnosed with major depressive disorder (MDD) we can better understand basic mind wandering research as it helps us understand the functions of more specific brain regions affected by this disordered attention, such as the subgenual-cingulate cortex, past just noting general engagement of the default network during mind wandering episodes.  While this study examines effects of rumination resulting from MDD, in order to do so, the study must also examine the rumination of HCs as a comparison group, thus offering important information about normal functioning.  This research is also important because most psychological disorders, like depression, involve symptoms that everyone experiences.  Therefore, clinical research  is relevant to normal functioning because it is just looking at the extreme cases of normal behaviors. Therefore, while excessive rumination is a symptom of MDD, HCS ruminate too, but just do so less of the time.  More specifically (see Figure bellow) this study found that HCs’ propensity to ruminate remains constant whether or not they are engaged in a task. MDDs, on the other hand, showed a difference in rumination propensity, with s significant reduction in rumination while engaged in a task (as seen in decreased connectivity) compared to during an off-task condition. 

This is particularly important in general because MDD affects approximately 17% of the U.S. population will suffer from at least one major depressive episode in their lifetime  (Lu, 2000).  Therefore, an understanding of the effects of increased rumination associated with MDD has a much larger impact than just on those currently diagnosed with MDD.  The fact that increased connectivity in the subgenual cingulate was only seen during off-task periods for MDD suggests that task engagement can temporarily relieve rumination and improve mood.  This therefore could also be an important tactic which could be used when HCs find themselves in a slightly depressed mood and task engagement at these times may act as a more permanent way to decrease rumination and improve their decreased mood back to its baseline state.

The work of Bonnelle et al. (2011) further supports the importance of the default mode network  (DMN) connectivity and associated measures of sustained attention.  It has been previously discussed that DMN activation increases when one is mind wandering.  The finding that sustained attention is impaired in those with a traumatic brain injury (TBI) is associated with an increased activation of the DMN follows in line with these past findings.  This research is particularly interesting in that the connectivity within the DMN, specifically that of the precuneus and posterior cingulate cortex, predict which patients will show sustained attention impairments.  By understanding that the impairments of TBIs’ ability to maintain consistent goal-directed behavior has to do with their increased activation of the DMN strengthens the previous findings of the importance of DMN activity regulation of normal brain function.  The changes in DMN connectivity are key to understanding impairment in sustained attention after TBI.  This is also an important finding because even though TBI seems to be able to sustain attention normally following the accident, it is over time in which such impairment occurs.  This is important for those patients as they increasingly may become less able to sustain attention though may not associate the TBI with this if they were originally told that their functioning was not impaired.

Manly et al. (2003) examine children diagnosed with ADHD, finding an associated impairment in their sustained attention. In the first study, they test a normative sample of healthy children in order to test the validity of the rather novel battery adapted from measures used to test adults’ sustained attention.  The second study then applied these measures to children diagnosed with ADHD.  In the first study they mention how they wanted to recreate the conditions in which most clinical tests occur, i.e. in rooms where experimenters can minimize noise and visual distractions.  In the second study, similar procedures were taken, however they mention that testing took place either at the clinic or at home.  I would think that these two environments could create different results as it would be much more difficult to control for distractions in one’s home environment, and I would therefore think that having the testing at home could create more distractions and therefore increase deficits in self-sustained attention of those subjects.  However, I also think that this type of testing in such an isolated environment in general is not useful because in everyday life there are distractions as well as others present, both of which will affect where and how one behaves and directs his or her attention. It is important to note that those diagnosed with ADHD in this study had not yet received any medication for treatment.  This is important to note because after being diagnosed with ADHD, patients most likely will be prescribed medication.  Therefore, it is important to understand the effects of sustained attention when on such medication.

Sayette, Reichle, & Schooler (2009) use both a self-caught and probe-caught method to understand the effects of alcohol on both mind wandering frequency and meta-awareness (i.e. propensity to catch oneself mind wandering).  This study, while comparing those given alcohol to those given a placebo, applies to all individuals that ever have had a drink, as it is analyzes individuals after consuming a very moderate amount of alcohol as opposed to studies on those with an alcohol addition.  In order to control for the many variables that affect alcohol intake, the researchers control for gender, age, body weight, height, and food intake.  However, I am a little skeptical about the chosen age range (21-35 years old), as I believe that those on the younger side of this group (who fall into the category of college students) probably drink more frequently and in a different manner (more binge drinking) compared to those towards the middle and end of this age group who tend to not drink as recklessly.  If so, both frequency and amount of alcohol intake would affect one’s alcohol tolerance and therefore could affect the results that the one drink in the study has on their sustained attention abilities.  Nevertheless, the study found that the alcohol group mind wandered about 25% more of the time than the placebo group during the reading task.