Experience during adolescence shapes brain development: From synapses and networks to normal and pathological behavior.

Adolescence is a period of dramatic neural reorganization creating a period of vulnerability and the possibility for the development of psychopathology. The maturation of various neural circuits during adolescence depends, to a large degree, on one's experiences both physical and psychosocial. This occurs through a process of plasticity which is the structural and functional adaptation of the nervous system in response to environmental demands, physiological changes and experiences.

Changes in cannabis potency and first-time admissions to drug treatment: a 16-year study in the Netherlands.

Background: The number of people entering specialist drug treatment for cannabis problems has increased considerably in recent years. The reasons for this are unclear, but rising cannabis potency could be a contributing factor.

Methods: Cannabis potency data were obtained from an ongoing monitoring programme in the Netherlands.

Is online information on ecstasy tablet content safe?

Background And Aims: In recent years, the prevalence of ecstasy use has increased in most European countries. Users can acquire information on ecstasy tablet composition through the internet. This study compares online information from two websites, Pillreports and Partyflock, to the validated Dutch Drugs Information and Monitoring System (DIMS) database, and aims to measure its accuracy and potential danger or value.

Limitations to the Dutch cannabis toleration policy: Assumptions underlying the reclassification of cannabis above 15% THC.

The Netherlands has seen an increase in Δ9-tetrahydrocannabinol (THC) concentrations from approximately 8% in the 1990s up to 20% in 2004. Increased cannabis potency may lead to higher THC-exposure and cannabis related harm. The Dutch government officially condones the sale of cannabis from so called 'coffee shops', and the Opium Act distinguishes cannabis as a Schedule II drug with 'acceptable risk' from other drugs with 'unacceptable risk' (Schedule I).

Potency trends of Δ9-tetrahydrocannabinol, cannabidiol and cannabinol in cannabis in the Netherlands: 2005-15.

Background And Aims: Between 2000 and 2005 the average percentage of Δ(9) -tetrahydrocannabinol (THC) in marijuana as sold in Dutch coffeeshops has increased substantially; the potency of domestic products (Nederwiet and Nederhasj) has particularly increased. In contrast with imported marijuana, Nederwiet hardly contained any cannabidiol (CBD), a cannabinoid that is thought to offset some of the adverse effects of THC. In 2005, the THC content in Nederwiet was significantly lower than in 2004.

4-Fluoroamphetamine in the Netherlands: more than a one-night stand.

Aims: To investigate the temporal pattern of appearance of a new psychoactive substance (4-fluoroamphetamine) on the Dutch drug market, as well as its patterns of use and effects.

Design: Data from the Drug Information and Monitoring System (DIMS) was used to investigate the emergence of 4-fluoroamphetamine on the Dutch drug market. An on-line questionnaire was used to study its patterns of use and effects.

[A patient in a methoxetamine-induced dissociative psychosis].

Background: The international drug market has dramatically changed with the emergence of various new psychoactive substances that are mostly being sold on the internet. One of those new psychoactive substances is methoxetamine (MXE), a structural analogue of ketamine.

Case Description: A 30-year-old man with no history of illness was presented to the accident and emergency department.

Therapeutic satisfaction and subjective effects of different strains of pharmaceutical-grade cannabis.

In The Netherlands, pharmaceutical-grade cultivated cannabis is distributed for medicinal purposes as commissioned by the Ministry of Health. Few studies have thus far described its therapeutic efficacy or subjective (adverse) effects in patients. The aims of this study are to assess the therapeutic satisfaction within a group of patients using prescribed pharmaceutical-grade cannabis and to compare the subjective effects among the available strains with special focus on their delta-9-tetrahydrocannabinol and cannabidiol content.

Does Cannabidiol Protect Against Adverse Psychological Effects of THC?

The recreational use of cannabis can have persistent adverse effects on mental health. Delta-9-tetrahydrocannabinol (THC) is the main psychoactive constituent of cannabis, and most, if not all, of the effects associated with the use of cannabis are caused by THC. Recent studies have suggested a possible protective effect of another cannabinoid, cannabidiol (CBD).

Possible long-term effects of γ-hydroxybutyric acid (GHB) due to neurotoxicity and overdose.

In several countries, including the Netherlands, the use of GHB seems to be rising. GHB is regarded by recreational users as an innocent drug without any side effects. Recently, the number of patients in treatment due to GHB addiction sharply increased.

Linking the pharmacological content of ecstasy tablets to the subjective experiences of drug users.

Rationale: Most studies on the subjective effects of ecstasy are based on the assumption that the substance that was taken is 3,4-methylenedioxymethamphetamine (MDMA). However, many tablets sold as ecstasy contain other substances and MDMA in varying doses. So far, few attempts have been made to take this into account while assessing subjective effects.

The Drug Information and Monitoring System (DIMS) in the Netherlands: implementation, results, and international comparison.

The Ministry of Health in the Netherlands has made illicit drug testing for drug users possible since the 1990s, in order to prevent serious health hazards associated with unexpected dangerous substances. This system of illicit drug testing is called the Drug Information and Monitoring System (DIMS). In nearly two decades, more than 100 000 drug samples have been handed in at DIMS testing facilities.

Impact of a transient instability of the ecstasy market on health concerns and drug use patterns in The Netherlands.

Background: A recent decline in MDMA-like substances in ecstasy tablets has been reported by a number of countries in the European Union. This study describes the instability of the ecstasy market in The Netherlands during 2008 and 2009, and investigates whether this had any impact on drug testing or patterns of drug use.

Methods: The health concerns of drug users handing in drug samples at drug testing facilities was measured using intervention time-series analysis.

Instability of the ecstasy market and a new kid on the block: mephedrone.

Recently, several reports have indicated instability of the ecstasy market in the Netherlands and other EU countries. In the current study, we demonstrate this instability in the Netherlands, showing a decrease of ecstasy tablets containing 3,4-methylenedioxymetamphetamine (MDMA) by more than 50% in 2009. In addition, we describe a partial replacement of MDMA in tablets sold as ecstasy by a previously unseen substance, mephedrone (or 4-methylmethcathinone).

Adolescent brain maturation, the endogenous cannabinoid system and the neurobiology of cannabis-induced schizophrenia.

Cannabis use during adolescence increases the risk of developing psychotic disorders later in life. However, the neurobiological processes underlying this relationship are unknown. This review reports the results of a literature search comprising various neurobiological disciplines, ultimately converging into a model that might explain the neurobiology of cannabis-induced schizophrenia.

The relationship of quality and price of the psychostimulants cocaine and amphetamine with health care outcomes.

A major component of the illicit drug market can be subcategorized as the psychostimulant drug market, with cocaine and amphetamine as popular constituents. In The Netherlands, an increase in both health care outcomes addiction treatment and hospital admissions was noted for both amphetamine and cocaine throughout a period of 17 years (1992-2008). Both cocaine price and quality showed a decrease in The Netherlands during the studied period.

Content of ecstasy in the Netherlands: 1993-2008.

Aims: The present paper outlines the results of analyses carried out on the content of tablets sold as ecstasy, collected in the Netherlands by the Drugs Information Monitoring System (DIMS) from January 1993 to December 2008.

Methods: During a period of 16 years, the DIMS analysed the content of 33 006 tablets sold as ecstasy that were handed in by numerous individual (potential) substance users. The DIMS results were compared with the results from various seized tablets to determine whether the DIMS is a monitor of the ecstasy consumer market.

An analysis of cocaine powder in the Netherlands: content and health hazards due to adulterants.

Aims: To report on trends in the content and adulterants present in street cocaine (powder) in the Netherlands and to describe the associated health hazards.

Design And Participants: Drug consumers handed in samples of cocaine powder from 1999 to 2007 for analysis. Reports were compiled of users' experiences with the samples received.

Pharmacological aspects of the combined use of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and gamma-hydroxybutyric acid (GHB): a review of the literature.

Epidemiological studies show that the use of club drugs is on the rise. Furthermore, the last few decades have seen a rise in patterns of polydrug use. One of the combinations frequently used is ecstasy (MDMA) with gammahydroxybutyrate (GHB).