147 Study protocol of the WHIMAS 7 In this population, the prevalence and severity of SVD and thus WMH will be higher, justifying our assumption of increased power. At the same time we do not want to risk an underpowered study. For example, in a case-control study comparing type 2 diabetes patients with healthy controls an average effect size of 0.37 for a more complex WMH shape was found.12 To illustrate this we have calculated the sample size with two different effect sizes that are higher than the one used in the initial calculation (0.2 and 0.3), but still lower than 0.37 (as found by De Bresser et al., 2018). These calculations resulted in a sample size of 42 or 29 participants. Therefore, a number of 50 participants should give the necessary statistical power to overcome biological and clinical variation. In order to be eligible to participate in the current study, a participant must meet all of the following criteria; participants receive care in the outpatient memory clinic or the geriatric clinic of the LUMC or the memory clinic of the Alrijne hospital in Leiden. Inclusion can be done if the participant is over 65 years of age and eligible for MRI. Moreover, the participant has to be native-level in the Dutch language. A potential participant who meets any of the following criteria will be excluded from participation in this study: • Claustrophobia • Contraindications for MRI such as metal implants and pacemaker • Regular use of benzodiazepines • Initiated treatment with antidepressants less than 6 weeks prior to inclusion • Not being able to provide written informed consent (assessed by the treating physician) • Individuals who have been declared mentally incapacitated • Other severe neurological disease outside of the dementia spectrum • Cognitive impairment due to known other neurological disease • Previous brain surgery 7.4.3 Clinical data We will collect basic demographic information including age, sex and education level. Information about medical history, psychiatric comorbidity, medication, and current blood values are extracted from the clinical file of the participant. Furthermore, a cardiovascular risk factor questionnaire is used to gather information about hypertension, diabetes, arrythmia, alcohol consumption, smoking, physical activity, and medical history. Another questionnaire includes questions about sleep
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