Improving Usual Care Outcomes in Major Depression in Youth by Targeting Memory Specificity: A Randomized Controlled Trial of Adjunct Computerised Memory Specificity Training (c-MeST)

Objective: Memory Specificity Training (MeST) improves the recall of past personal experiences, an impairment in Major Depressive Disorder (MDD). Extending on previous findings that computerised MeST (c-MeST) improves memory specificity and depressive symptoms in adults, this study aimed to answer two questions: 1) does c-MeST improve memory specificity and depressive symptoms in youth with MDD; and 2) does c-MeST improve memory specificity and depression in addition to other treatment? Methods: Participants aged 15-25 (N=359, 76.5% female; M age=19.2, SD=3.1), receiving predominantly psychological therapy or counselling (85%) and/or antidepressants (52.9%) were randomised to c-MeST or wait-list. Cognitive and clinical outcomes were assessed at baseline and at one, three, and six-month follow-ups. Results: The c-MeST group reported higher memory specificity at one-month (M change=1.13, 95%CI [0.16,2.10], d=.42, p=.022), but not other follow-ups. There was no significant group difference for Major Depressive Episode diagnosis at six-months (55.6% c-MeST vs. 68.8% control, odds ratio=0.56 95%CI [0.21,1.53], p=.266), but the c-MeST group did report lower depressive symptoms at one (M change=-1.84, 95%CI[-3.42,-0.25], d = .42, p = .023) and six-month follow-ups (M change=-3.91, 95%CI [-6.19,-1.63], d = .84, p = .001). Conclusions: c-MeST reduces symptoms in youth with MDD when provided alongside other treatments. There was some evidence that change in memory specificity drives these changes. Contrary to previous findings, specificity effects were not maintained, potentially due to the low intensity of c-MeST in this study. Further study is needed to understand more about co-occurring mechanisms that produce antidepressant effects.

Specificity effects in reasoning with counterintuitive and arbitrary conditionals

When people have prior knowledge about an inference, they accept conclusions from specific conditionals (e.g., “If Jack does sports, then Jack loses weight”) more strongly than for unspecific conditionals (e.g., “If a person does sports, then the person loses weight”). But can specific phrasings also elevate the acceptance of conclusions from unbelievable conditionals? In Experiment 1, we varied the specificity of counterintuitive conditionals, which described the opposite of what is expected according to everyday experiences (“If Lena/a person studies hard, then Lena/the person will not do well on the test”). In Experiment 2, we varied the specificity of arbitrary conditionals, which had no obvious link between antecedent and consequent (“If Mary/a person goes shopping, then Mary/ the person gets pimples”). All conditionals were embedded in MP and AC inferences. Participants were instructed to reason as in daily life and to evaluate the conclusions on a 7-point Likert scale. Our results showed a specificity effect in both experiments: participants gave higher acceptance ratings for specific than for unspecific conditionals.

Purification and biochemical characterization of polyphenol oxidase from seeds of melon (Citrullus colocynthis)

Polyphenol oxidase (PPO) is an enzyme that is responsible for the enzymatic browning of fruits and vegetables. This is generally undesired process and need to be prevented in food technology. PPO from seeds of Citrullus colocynthis was purified, the physicochemical properties such as effects of pH and temperature, substrate specificity, effects of inhibitors and cations on PPO activity and the kinetic parameters for four substrates namely, catechol, L-DOPA, gallic acid and tyrosine, were determined. The purification steps resulted in 41-fold with 10 % yield, and the optima pH and temperature values for PPO from C. colocynthis were found to be pH 7.0 and 60 °C, respectively using catechol as substrate. About 9 % enzyme initial activity was retained after 60 min of incubation at 80 °C, and the apparent molecular weight was determined as 42 kDa by partially denaturing SDS-PAGE. PPO activity was inhibited by ascorbic acid, SDS and certain divalent (Ca2+, Zn2+, Mg2+ and, Fe2+) and monovalent (Na+) metal. Moreover, purified enzyme solution showed diphenolase activity toward catechol, gallic acid, L-DOPA and monophenolase activity toward tyrosine, therefore, tyrosinase was identified as the only one PPO in C. colocynthis seeds. This study revealed the use of temperature above 80 °C to inhibit PPO activity during processing and storage of melon seeds.