"The Trouble With Brain Scans"
The Trouble With Brain Scans
by Vaughn Bell
27 May 2012
Read the full piece here.
News about our knowledge of the brain and behavior
from Anthony Risser, Ph.D.
Prospective memory (PM) is the ability to remember to execute delayed intentions. Previous studies indicate that PM is impaired in persons with mild cognitive impairment (MCI) and dementia, but the extent, nature, and cognitive correlates are unclear. A meta-analytic review was, therefore, performed (literature search 1990 to July 2011) on case-control studies on PM in dementia (10 studies, 336 patients, 505 controls) and MCI (7 studies, 225 patients, 253 controls). Differences between event-based and time-based PM and between measures of prospective and retrospective memory were examined, as well as correlations with other cognitive functions. Results showed that patients with dementia or MCI exhibit large deficits in PM (Hedges' d -1.62 [95% confidence interval -1.98 to -1.27; p < .0001] for dementia; -1.24 [-1.51 to -0.995; p < .0001] for MCI; difference dementia vs. MCI: QM = 1.94, p = .16). Impairments were comparable in size for event-based and time-based PM (p > .05), as well as for prospective and retrospective memory (p > .05). PM showed modest correlations with measures of retrospective memory (median r = 0.27) and executive functioning (median r = 0.30). PM appears a valid construct in neuropsychological assessment in patients with dementia or MCI, but more insight is needed in the optimal characteristics of PM tasks to be used in clinical practice. (JINS, 2012, 18, 1-11).
PMID: 22595831 [PubMed - as supplied by publisher]
"Sluggish cognitive tempo" (SCT) is a construct hypothesized to describe a constellation of behaviors that includes daydreaming, lethargy, drowsiness, difficulty sustaining attention, and underactivity. Although the construct has been inconsistently defined, measures of SCT have shown associations with symptoms of attention-deficit/hyperactivity disorder (ADHD), particularly inattention. Thus, better characterization of SCT symptoms may help to better predict specific areas of functional difficulty in children with ADHD. The present study examined psychometric characteristics of a recently developed 14-item scale of SCT (Penny et al., Psychological Assessment 21:380-389, 2009), completed by teachers on children referred for outpatient neuropsychological assessment. Exploratory factor analysis identified three factors in the clinical sample: Sleepy/Sluggish, Slow/Daydreamy, and Low Initiation/Persistence. Additionally, SCT symptoms, especially those loading on the Sleepy/Sluggish and Slow/Daydreamy factors, correlated more strongly with inattentive than with hyperactive/impulsive symptoms, while Low Initiation/Persistence symptoms added significant unique variance (over and above symptoms of inattention) to the predictions of impairment in academic progress.
PMID: 22566025 [PubMed - as supplied by publisher]
Awake mental replay of past experiences critical for learning
07 May 2012