Practice Effects May Influence MCI Detection
Failing to account for practice effects may lead to underdiagnosis of mild cognitive impairment (MCI), according to a study published May 14 in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring. In an approximately six-year follow-up of the Vietnam Era Twin Study of Aging, researchers retested the cognitive function of 995 late-middle-aged men. In addition, the researchers tested 170 age-matched study replacements for the first time. The investigators used group differences to calculate practice effects after controlling for attrition effects and generated MCI diagnoses from practice-adjusted scores. There were significant practice effects on most cognitive domains, even though participants’ uncorrected scores may have declined. Conversion to MCI doubled after correcting for practice effects, from 4.5% to 9%.
Elman JA, Jak AJ, Panizzon MS, et al. Underdiagnosis of mild cognitive impairment: a consequence of ignoring practice effects. Alzheimers Dement (Amst). 2018;10:372-381.
Brain Iron Levels Predict Disability in Patients With MS
Iron levels in the brains of patients with multiple sclerosis (MS) measured using quantitative susceptibility mapping (QSM) may help identify people at a higher risk of physical disability, according to a study published online ahead of print July 17 in Radiology. In this prospective study, 600 participants with MS and 250 age- and sex-matched healthy controls were imaged with 3.0-T MRI. The researchers assessed QSM and MRI volumetric differences between study groups and associations with clinical outcomes using analysis of covariance, multivariable linear regression, and voxelwise analyses, controlling for age and sex. Compared with controls, participants with MS had lower thalamic susceptibility and higher susceptibility of basal ganglia. Lower thalamic susceptibility was associated with longer disease duration, greater disability, and secondary-progressive disease course.
Zivadinov R, Tavazzi E, Bergsland N, et al. Brain iron at quantitative MRI is associated with disability in multiple sclerosis. Radiology. 2018 Jul 17 [Epub ahead of print].