The recovered memory/false memory debate. Comment

Does sleep disruption mediate the effects of childhood maltreatment on brain structure?

Background: Childhood maltreatment is associated with alterations in morphology of stress susceptible brain regions. Maltreatment is also known to markedly increase risk for psychopathology and to have an enduring disruptive effect on sleep. Objective: To determine whether abnormalities in sleep continuity have effects on brain morphometry and to evaluate the extent to which sleep impairments mediate the effects of maltreatment on brain structure. Method: Maltreatment and Abuse Chronology of Exposure (MACE) scale ratings, actigraph-assessed sleep and 3T MRI were obtained on N = 37 18-19-year-old participants recruited from the community (N = 34 with neuroimaging). Results: Fourteen participants had no history of maltreatment while N = 23 were exposed, on average, to 4.7 types of maltreatment. Multiplicity of maltreatment was strongly associated with reduced sleep efficiency, increased wake after sleep onset time and number/duration of awakenings, which were independent of effects of maltreatment on depression and anxiety. The most important predictors of impaired sleep were exposure to parental non-verbal emotional abuse at 9-10 years of age. Reduced sleep efficiency correlated with reduced grey matter volume in hippocampus including CA1 subfield, molecular layer and dentate gyrus as well as inferior frontal gyrus and insula. Sleep mediated 39-46% of the effects of maltreatment on volume of hippocampal structures and inferior frontal gyrus. Conclusions: Actigraph-assessed sleep is disrupted in maltreated late teens and mediates a significant portion of the effects of maltreatment on hippocampal volume. Studies are needed to assess whether efforts to enhance sleep in maltreated children can pre-empt or ameliorate neurobiological consequences of maltreatment.

Mood dysregulation and affective instability in emerging adults with childhood maltreatment: An ecological momentary assessment study

Childhood maltreatment increases risk for mood, anxiety, substance use and personality disorders and is associated with alterations in structure, function and connectivity of brain regions involved in emotional regulation. We sought to assess whether maltreatment was specifically associated with disturbances in positive or negative mood regulation. Ecological momentary ratings were collected with a wristwatch-like device with joy-stick (Seiko ecolog) approximately six times per day over a week in 60 unmedicated participants (22 control, 38 maltreated, 18-25 years old). Forty-five percent of maltreated subjects had a history of major depression but all were currently euthymic. Principal component analysis with varimax rotation was used to provide orthogonal measures of positive and negative valence, which were analyzed for indices of variability, circadian rhythmicity and persistence, using linear and non-linear hierarchical modeling and Hurst analysis. Groups did not differ in mean levels of positive or negative affect. Maltreated subjects had increased variability and circadian and hemicircadian abnormalities in ratings of positive but not negative affect. Conversely, they had higher estimated Hurst exponents for negative but not positive affect ratings indicating a greater degree of persistence. Abnormalities in variability, rhythmicity and persistence were present in both maltreated subjects with and without histories of major depression. These findings suggest that both positive and negative valence systems may be dysregulated in individuals with childhood maltreatment. However the nature of the dysregulation appears to differ fundamentally in these domains, as positive mood ratings were more variable and negative ratings more persistent.