RESUMO
The frequent co-occurrence of post-traumatic stress disorder (PTSD) and substance use disorders (SUDs) leads to manifestations of both conditions that are more severe and more resistance to treatment than single disorders. One hypothesis to explain this synergy is the impact of intrusive memories on craving which, in turn, increases the risk of relapse among patients with substance use disorders. The aim of this systematic review is to examine this possibility by assessing the impact of PTSD and its symptoms on craving among dual disorder patients. Using PRISMA criteria, four databases were comprehensively searched up to June, 2021, in order to identify all candidate studies based on broad key words. Resulting studies were then selected if they examined the impact of PTSD or PTSD symptoms on craving, and if they used standardized assessments of PTSD, SUD, and craving. Twenty-seven articles matched the selection criteria and were included in this review. PTSD was found to be significantly associated with increased craving levels among patients with alcohol, cannabis, cocaine, tobacco, and other substance use disorders. Exposition to traumatic cues among dual disorder patients was also shown to trigger craving, with an additive effect on craving intensity when exposure to substance-related cues occurred. In addition, certain studies observed a correlation between PTSD symptom severity and craving intensity. Concerning mechanisms underlying these associations, some findings suggest that negative emotional states or emotion dysregulation may play a role in eliciting craving after traumatic exposure. Moreover, these studies suggest that PTSD symptoms may, independently of emotions, act as powerful cues that trigger craving. These findings argue for the need of dual disorder treatment programs that integrate PTSD-focused approaches and emotion regulation strategies, in addition to more traditional interventions for craving management.
RESUMO
A tris-tridentate segmental ligand has been designed for the self-assembly of homotrimetallic triple-stranded lanthanide helicates possessing different coordination sites along the threefold axis.
RESUMO
The planar aromatic tridentate ligand 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (L(1)) reacts with Ln(III) (Ln = La-Lu) in acetonitrile to give the successive complexes [Ln(L(1))(n)()](3+) (n = 1-3). Stability constants determined by spectrophotometry and potentiometric competitive titrations with Ag(I) show that the 1:1 and the 1:2 complexes display the usual thermodynamic behavior associated with electrostatic effects while the 1:3 complexes exhibit an unusual selectivity for the midrange Ln(III) ions (Delta log K(3)(Gd-Lu) approximately 4). A detailed investigation of the solution structure of [Ln(L(1))(3)](3+) (Ln = La-Dy) reveals that the closely packed triple-helical structure found in the crystal structure of [Eu(L(1))(3)](3+) is retained in acetonitrile for the complete series. A sharp control of the coordination cavity results from the interstrand pi-stacking interactions which appear to be optimum for Gd(III). For Yb(III), for instance, a 1:2 complex only could be isolated, which crystallizes as a hydroxo-bridged dimer [Yb(OH)(L(1))(2)](2)(ClO(4))(4)(HClO(4))(0.5)(CH(3)CN)(7.32)(L(1))(0.5) (triclinic, P&onemacr;, a = 13.250(2) Å, b = 16.329(2) Å, c = 27.653(3) Å, alpha = 99.941(9) degrees, beta = 93.394(9) degrees, gamma = 108.114(9) degrees, Z = 2). The binding of bulky substituents to the nitrogen atoms of the benzimidazole side arms in L(4) (i) severely affects the wrapping process, (ii) leads to less stable triple-helical building blocks, and (iii) removes the size-discriminating effect. The last can however be restored if a strong electron-donor group is connected to the central pyridine ring in L(8). Stability and solution structure data for [Ag(2)(L(i)())(2)](2+) (i = 1, 4, 8) are also reported and discussed.
