Normative data from linear and nonlinear quantile regression in CANTAB: Cognition in mid-to-late life in an epidemiological sample.

INTRODUCTION: Normative cognitive data can help to distinguish pathological decline from normal aging. This study presents normative data from the Cambridge Neuropsychological Test Automated Battery, using linear regression and nonlinear quantile regression approaches. METHODS: Heinz Nixdorf Recall study participants completed Cambridge Neuropsychological Test Automated Battery tests: paired-associate learning, spatial working memory, and reaction time. Data were available for 1349-1529 healthy adults aged 57-84 years. Linear and nonlinear quantile regression analyses examined age-related changes, adjusting for sex and education. Quantile regression differentiated seven performance bands (percentiles: 97.7, 93.3, 84.1, 50, 15.9, 6.7, and 2.3). RESULTS: Normative data show age-related cognitive decline across all tests, but with quantile regression revealing heterogeneous trajectories of cognitive aging, particularly for the test of episodic memory function (paired-associate learning). DISCUSSION: This study presents normative data from Cambridge Neuropsychological Test Automated Battery in mid-to-late life. Quantile regression can model heterogeneity in age-related cognitive trajectories as seen in the paired-associate learning episodic memory measure.

Effects of short-term quetiapine treatment on emotional processing, sleep and circadian rhythms.

BACKGROUND: Quetiapine is an atypical antipsychotic that can stabilise mood from any index episode of bipolar disorder. This study investigated the effects of seven-day quetiapine administration on sleep, circadian rhythms and emotional processing in healthy volunteers. METHODS: Twenty healthy volunteers received 150 mg quetiapine XL for seven nights and 20 matched controls received placebo. Sleep-wake actigraphy was completed for one week both pre-dose and during drug treatment. On Day 8, participants completed emotional processing tasks. RESULTS: Actigraphy revealed that quetiapine treatment increased sleep duration and efficiency, delayed final wake time and had a tendency to reduce within-day variability. There were no effects of quetiapine on subjective ratings of mood or energy. Quetiapine-treated participants showed diminished bias towards positive words and away from negative words during recognition memory. Quetiapine did not significantly affect facial expression recognition, emotional word categorisation, emotion-potentiated startle or emotional word/faces dot-probe vigilance reaction times. CONCLUSIONS: These changes in sleep timing and circadian rhythmicity in healthy volunteers may be relevant to quetiapine's therapeutic actions. Effects on emotional processing did not emulate the effects of antidepressants. The effects of quetiapine on sleep and circadian rhythms in patients with bipolar disorder merit further investigation to elucidate its mechanisms of action.

Daily rest-activity patterns in the bipolar phenotype: A controlled actigraphy study.

This study assessed daily rest-activity patterns in euthymic, medication-naïve bipolar phenotype individuals. The Mood Disorder Questionnaire was used to identify 19 bipolar phenotype individuals and 21 controls. Participants wore an Actiwatch-L for 2 weeks to assess their sleep behaviour and circadian rest-activity rhythmicity. Bipolar phenotype individuals had increased movement during sleep, as assessed by the fragmentation index, greater activity levels during their least active 5 h (2 am-7 am), and lower circadian relative amplitude compared to controls. Higher activity levels during sleep affecting circadian amplitude in young adults with the bipolar phenotype may be associated with vulnerability for developing mood disorder.

Short-term quetiapine treatment alters the use of reinforcement signals during risky decision-making and promotes the choice of negative expected values in healthy adult males.

Effective decision-making can involve using environmental signals about the possible good and bad outcomes, and their probabilities, to select optimal actions. Problematic decision-making in psychiatric disorders, and particularly bipolar illness, may result from disrupted use of these reinforcement cues, leading to actions that reflect or precipitate pathological changes in mood. Previous experiments indicate that the processing of reinforcement cues while selecting between risky actions can be influenced by dopamine and serotonin activity. Quetiapine is an atypical antipsychotic agent with a complex pharmacology, including antagonist actions at 5-HT2A and, to a lesser extent, D2 receptors. Here, we investigated the effects of (short-term) treatment with quetiapine on the risky decision-making of healthy human adults. Twenty participants received 150 mg of quetiapine XL for 7 d, whereas 20 age- and IQ-matched participants received a placebo. On the eighth day, all participants completed a risky decision-making task that involved making a series of choices between two simultaneously presented gambles that differed in the magnitudes of their possible gains and losses, and the probabilities with which these outcomes were delivered. Quetiapine treatment was associated with a marked tendency to choose options with negative expected values compared with placebo treatment in male but not female participants. Our results demonstrate that antagonism of serotonin and dopamine receptor activity can alter the way individuals use information about gains and losses when selecting between risky actions, possibly reflecting gender-specific differences in risk attitudes. These effects may be beneficial by correcting decision-making biases that feature in mood disorders.

The common adolescent bipolar phenotype shows positive biases in emotional processing.

OBJECTIVES: Bipolar disorder is associated with abnormalities in emotional processing that persist into periods of remission. However, studies of euthymic bipolar disorder patients may be confounded by the experience of mood episodes and medication. We therefore assessed an adolescent group for vulnerability markers associated with the bipolar phenotype. METHODS: The Mood Disorder Questionnaire (MDQ) is a screening tool for bipolar disorder that targets mood-elevation symptoms. We selected 32 high-scoring students (≥ 7 symptoms) with the adolescent bipolar phenotype and 30 low-scoring controls (≤ 3 symptoms) and screened them with the Mini International Neuropsychiatric Interview-Plus for bipolar disorder and other psychiatric disorders. We investigated emotional processing by assessing facial expression recognition, emotional memory, emotion-potentiated startle, and a dot-probe task. RESULTS: Of the high-MDQ participants, 12 were in remission from bipolar disorder defined by DSM-IV-TR and interview (bipolar II disorder/bipolar disorder not otherwise specified) and 3 from major depressive disorder. High-MDQ participants had higher levels of neuroticism, low mood, and lifetime anxiety comorbidity and alcohol dependence compared with low-MDQ participants. The high-MDQ group showed facilitated recognition of surprised and neutral facial expressions and enhanced processing of positive versus negative information in emotional recognition memory and emotion-potentiated startle. There were no effects on emotional categorisation/recall memory or attentional bias in the dot-probe task. CONCLUSIONS: These results suggest that students with the common adolescent bipolar phenotype show positive emotional processing biases despite increased levels of neuroticism, low mood, and anxiety. Such effects may represent a psychological vulnerability marker associated with the bipolar phenotype.