Anton J M Loonen

Prof. Anton J M Loonen

University of Groningen, Groningen, The Netherlands
orcid

Research Focus & Metrics

Academic Career Length

50Years (1977-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 December 2010 in The British Journal of Psychiatry
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Journal Article
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ASA. B. P. Staring
A. B. P. Staring
MGMark van der Gaag
Mark van der Gaag
GKG. T. Koopmans
G. T. Koopmans
JSJ. P. Selten
J. P. Selten
JBJ. M. Van Beveren
J. M. Van Beveren
CMC. L. Mulder
C. L. Mulder
Background: Interventions to improve adherence to treatment in people with psychotic disorders have produced inconclusive results. We developed a new treatment, treatment adherence therapy (TAT), whose intervention modules are tailored to the reasons for an individual's non-adherence.Aims: To examine the effectiveness of TAT with regard to service engagement and medication adherence in out-patients with psychotic disorders who engage poorly.Method: Randomised controlled study of TAT v. treatment as usual (TAU) in 109 out-patients. Most outcome measurements were performed by masked assessors. We used intention-to-treat multivariate analyses (Dutch Trial Registry: NTR1159).Results: Treatment adherence therapy v. TAU significantly benefited service engagement (Cohen's d = 0.48) and medication adherence (Cohen's d = 0.43). Results remained significant at 6-month follow-up for medication adherence. Near-significant effects were also found regarding involuntary readmissions (1.9% v. 11.8%, P = 0.053). Symptoms and quality of life did not improve.Conclusions: Treatment adherence therapy helps improve engagement and adherence, and may prevent involuntary admission.

31 March 2007 in European Journal of Clinical Pharmacology
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RMRob J. van Marum
Rob J. van Marum
MWMichelle A. Wegewijs
Michelle A. Wegewijs
ALAnton J M Loonen
Anton J M Loonen
EBErna Beers
Erna Beers
Hypothermia is an adverse drug reaction (ADR) of antipsychotic drug (APD) use. Risk factors for hypothermia in ADP users are unknown. We studied which risk factors for hypothermia can be identified based on case reports. Case reports of hypothermia in APD-users found in PUBMED or EMBASE were searched for risk factors. The WHO international database for Adverse Drug Reactions was searched for reports of hypothermia and APD use. The literature search resulted in 32 articles containing 43 case reports. In the WHO database, 480 reports were registered of patients developing hypothermia during the use of APDs which almost equals the number of reports for hyperthermia associated with APD use (n = 524). Hypothermia risk seems to be increased in the first days following start or dose increase of APs. APs with strong 5-HT2 antagonism seem to be more involved in hypothermia; 55% of hypothermia reports are for atypical antipsychotics. Schizophrenia was the most prevalent diagnosis in the case reports. Especially in admitted patients who are not able to control their own environment or physical status, frequent measurements of body temperature (with a thermometer that can measure low body temperatures) must be performed in order to detect developing hypothermia.

1 September 2017 in Neuroscience & Biobehavioral Reviews
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ABAlbert Batalla
Albert Batalla
Judith HombergJudith Homberg
Judith Homberg
TLTatiana V. Lipina
Tatiana V. Lipina
GSGuillaume Sescousse
Guillaume Sescousse
MLMaartje Luijten
Maartje Luijten
ALAnton J M Loonen
Anton J M Loonen

20 December 2012 in CNS Spectrums
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ALAnton J M Loonen
Anton J M Loonen
SISvetlana Ivanova
Svetlana Ivanova
Dyskinesia is an extrapyramidal movement disorder characterized by involuntary, repetitive, irregular motions that affect the mouth and face and/or the limbs and trunk. Tardive dyskinesia (TD) is a well-known complication of long-term treatment with antipsychotic drugs. Dyskinesia is also induced with levodopa, a treatment for Parkinson's disease, and it occurs spontaneously as a symptom of Huntington's disease. Research on the pathogenesis of TD has focused on a dysfunction of either the dopaminergic or serotonergic system. However, recent evidence has suggested that we should focus on the possible damage of GABAergic medium spiny neurons (MSNs). MSNs are the first station in the cortico-striato-thalamo-cortical circuit that regulates the amplitude and velocity of movements. Two pathways can be distinguished in this circuit: a direct pathway, which increases movements (hyperkinesia), and an indirect pathway, which decreases movements (hypokinesia). Both pathways are activated by glutamatergic corticostriatal neurons. Here, we discuss some evidence that supports the hypothesis that indirect pathway MSNs are damaged in dyskinesia.

10 November 2016 in Frontiers in Human Neuroscience
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Journal Article
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ALAnton J M Loonen
Anton J M Loonen
SISvetlana Ivanova
Svetlana Ivanova
According to our model of the regulation of appetitive-searching versus distress-avoiding behaviors, the motivation to display these essential conducts is regulated by two parallel cortico-striato-thalamo-cortical, re-entry circuits, including the core and the shell parts of the nucleus accumbens, respectively. An entire series of basal ganglia, running from the caudate nucleus on one side, to the centromedial amygdala on the other side, controls the intensity of these reward-seeking and misery-fleeing behaviors by stimulating the activity of the (pre)frontal and limbic cortices. Hyperactive motivation to display behavior that potentially results in reward induces feelings of hankering (relief leads to pleasure). Hyperactive motivation to exhibit behavior related to avoidance of misery results in dysphoria (relief leads to happiness). These two systems collaborate in a reciprocal fashion. In clinical depression, a mismatch exists between the activities of these two circuits: the balance is shifted to the misery-avoiding side. Five theories have been developed to explain the mechanism of depressive mood disorders, including the monoamine, biorhythm, neuro-endocrine, neuro-immune, and kindling/neuroplasticity theories. This paper describes these theories in relationship to the model (described above) of the regulation of reward-seeking versus misery-avoiding behaviors. Chronic stress that leads to structural changes may induce the mismatch between the two systems. This mismatch leads to lack of pleasure, low energy, and indecisiveness, on one hand, and dysphoria, continuous worrying, and negative expectations on the other hand. The neuroplastic effects of monoamines, cortisol, and cytokines may mediate the induction of these structural alterations. Long-term exposure to stressful situations (particularly experienced during childhood) may lead to increased susceptibility for developing this condition. This hypothesis opens up the possibility of treating depression with psychotherapy. Genetic and other biological factors (toxic, infectious, or traumatic) may increase sensitivity to the induction of relevant neuroplastic changes. Reversal or compensation of these neuroplastic adjustments may explain the effects of biological therapies in treating depression.

1 February 2016 in Medical Hypotheses
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Journal Article
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ALAnton J M Loonen
Anton J M Loonen
SISvetlana Ivanova
Svetlana Ivanova
The introduction of selective serotonin reuptake inhibitors has gradually changed the borders of the major depression disease class. Anhedonia was considered a cardinal symptom of endogenous depression, but the potential of selective serotonin reuptake inhibitors to treat anxiety disorders has increased the relevance of stress-induced morbidity. This shift has led to an important heterogeneity of current major depressive disorder. The complexity can be disentangled by postulating the existence of two different but mutually interacting neuronal circuits regulating the intensity of anhedonia (lack of pleasure) and dysphoria (lack of happiness). These circuits are functionally dominated by partly closed limbic (regulating misery-fleeing behaviour) and extrapyramidal (regulating reward-seeking behaviour) cortico-striato-thalamo-cortical (CSTC) circuits. The re-entry circuits include the shell and core parts of the accumbens nucleus, respectively. Pleasure can be considered to result from finding relief from the hypermotivation to exhibit rewarding behaviour, and happiness from finding relief from negative or conflicting circumstances. Hyperactivity of the extrapyramidal CSTC circuit results in craving, whereas hyperactivity of the limbic system results in dysphoria.