Visual analogue scales are widely used to measure subjective responses. Norris' 16 visual analogue scales (N_VAS) measure subjective feelings of alertness and mood. Up to now, different scientists... Show moreVisual analogue scales are widely used to measure subjective responses. Norris' 16 visual analogue scales (N_VAS) measure subjective feelings of alertness and mood. Up to now, different scientists have clustered items of N_VAS into different ways and Bond and Lader's way has been the most frequently used in clinical research. However, there are concerns about the stability of this clustering over different subject samples and different drug classes. The aim of this study was to test whether Bond and Lader's clustering was stable in terms of subject samples and drug effects. Alternative clustering of N_VAS was tested. Data from studies with 3 types of drugs: cannabinoid receptor agonist (delta-9-tetrahydrocannabinol [THC]), muscarinic antagonist (scopolamine), and benzodiazepines (midazolam and lorazepam), collected between 2005 and 2012, were used for this analysis. Exploratory factor analysis (EFA) was used to test the clustering algorithm of Bond and Lader. Consensus clustering was performed to test the stability of clustering results over samples and over different drug types. Stability analysis was performed using a three-cluster assumption, and then on other alternative assumptions. Heat maps of the consensus matrix (CM) and density plots showed instability of the three-cluster hypothesis and suggested instability over the 3 drug classes. Two- and four-cluster hypothesis were also tested. Heat maps of the CM and density plots suggested that the two-cluster assumption was superior. In summary, the two-cluster assumption leads to a provably stable outcome over samples and the 3 drug types based on the data used. Show less
Zijlmans, J.; Duin, L. van; Jorink, M.; Marhe, R.; Luijks, M.J.A.; Crone, M.; ... ; Bevaart, F. 2021
Multiproblem young adults present with major problems across key life domains, but empirical studies investigating the nature of multiproblem behavior in accordance to ecobiodevelopmental theory... Show moreMultiproblem young adults present with major problems across key life domains, but empirical studies investigating the nature of multiproblem behavior in accordance to ecobiodevelopmental theory are scarce. To address this gap, we performed a cluster analysis on indicators spanning the key life domains addiction, mental health, social network, and justice. In a large sample (N = 680) of multiproblem young adults, we identified five subgroups labeled "severe with alcohol and cannabis problems" (4.3%), "severe with cannabis problems" (25.6%), "severe without alcohol or drug problems" (33.2%), "moderate with mental health problems" (22.9%), and "moderate without mental health problems" (14.0%). There were large differences between the severe and moderate groups in terms of childhood risk factors such as emotional and physical abuse, concerning baseline functioning such as comorbid disorders and aggressive behavior, and in the outcome measure of violent offending. Our findings indicate that multiproblem young adult behavior clusters within profiles that differ according to the severity and nature of problems. Investing in screening for clustered problems may be beneficial for early problem differentiation and selection of appropriate intervention before and during treatment programs. Show less
Jaarsma-Coes, M.G.; Ghaznawi, R.; Hendrikse, J.; Slump, C.; Witkamp, T.D.; Graaf, Y. van der; ... ; Second Manifestn ARTerial Dis SMAR 2020
Neurodegenerative and neurovascular diseases lead to heterogeneous brain abnormalities. A combined analysis of these abnormalities by phenotypes of the brain might give a more accurate... Show moreNeurodegenerative and neurovascular diseases lead to heterogeneous brain abnormalities. A combined analysis of these abnormalities by phenotypes of the brain might give a more accurate representation of the underlying aetiology. We aimed to identify different MRI phenotypes of the brain and assessed the risk of future stroke and mortality within these subgroups. In 1003 patients (59 +/- 10 years) from the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study, different quantitative 1.5T brain MRI markers were used in a hierarchical clustering analysis to identify 11 distinct subgroups with a different distribution in brain MRI markers and cardiovascular risk factors, and a different risk of stroke (Cox regression: from no increased risk compared to the reference group with relatively few brain abnormalities to HR = 10.34; 95% CI 3.80 <-> 28.12 for the multi-burden subgroup) and mortality (from no increased risk compared to the reference group to HR = 4.00; 95% CI 2.50 <-> 6.40 for the multi-burden subgroup). In conclusion, within a group of patients with manifest arterial disease, we showed that different MRI phenotypes of the brain can be identified and that these were associated with different risks of future stroke and mortality. These MRI phenotypes can possibly classify individual patients and assess their risk of future stroke and mortality. Show less
