T2 signal hyperintensities (WMHs) are readily visualized on brain scans of elderly individuals. WMHs occur both in demented patients and in healthy elderly subjects. The main risk factors associated with development of WMHs are older age and hypertension (
1). Vladimir Hachinski proposed the descriptive term “leukoaraiosis” to refer to these changes, based on the Greek for “white matter rarefaction” (
- Longstreth Jr., WT
- Manolio TA
- Arnold A
- Burke GL
- Bryan N
- Jungreis CA
- et al.
Clinical correlates of white matter findings on cranial magnetic resonance imaging of 3301 elderly people. The Cardiovascular Health Study.
Stroke. 1996; 27: 1274-1282
2). The origin and pathophysiology of WMHs are not fully understood. Histopathological-imaging correlational studies in post-mortem brains have shown that WMHs reflect heterogeneous histological changes including myelin pallor, myelin loss, axonal loss, gliosis and incomplete white matter infarction (
- Hachinski VC
- Potter P
- Merskey H.
Arch Neurol. 1987; 44: 21-23
- Fazekas F
- Kleinert R
- Offenbacher H
- Schmidt R
- Kleinert G
- Payer F
- et al.
Pathologic correlates of incidental MRI white matter signal hyperintensities.
Neurology. 1993; 43: 1683-1689
4). Some of these histological changes are thought to be ischemic in origin, but non-vascular mechanisms such as CSF transudation through discontinuities of the ependyma into the brain interstitium are also important. Brain pathological examination of Alzheimer's disease (AD) cases have demonstrated deep white matter rarefaction with partial loss of myelin and axons, referred to as selective incomplete WM infarction, and are thought to result from non-amyloid arteriolosclerosis associated with hypoperfusion (
- Fazekas F
- Schmidt R
- Scheltens P.
Pathophysiologic mechanisms in the development of age-related white matter changes of the brain.
Dement Geriatr Cogn Disord. 1998; 9 Suppl 1: 2-5
5). Accordingly, increased volume or higher severity of PWMHs are found in patients with AD dementia (
- Englund E
- Brun A
- Alling C.
White matter changes in dementia of Alzheimer's type. Biochemical and neuropathological correlates.
J Neurol. 1988; 111: 1425-1439
- Fazekas F
- Chawluk JB
- Alavi A
- Hurtig HI
- Zimmerman RA.
MR signal abnormalities at 1.5 T in Alzheimer's dementia and normal aging.
AJR. 1987; 149: 351-356
7).WMHs in conjunction with lacunar brain infarctions are also highly prevalent in subcortical ischemic vascular disease (SIVD), the most common type of vascular dementia (
- Lee S
- Viqar F
- Zimmerman ME
- Narkhede A
- Tosto G
- Benzinger TL
- et al.
White matter hyperintensities are a core feature of Alzheimer's disease: Evidence from the dominantly inherited Alzheimer network.
Ann Neurol. 2016; 79: 929-939
- Román GC
- Erkinjuntti T
- Wallin A
- Pantoni L
- Chui HC.
Subcortical ischaemic vascular dementia.
Lancet Neurol. 2002; 1: 426-436
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- Clinical correlates of white matter findings on cranial magnetic resonance imaging of 3301 elderly people. The Cardiovascular Health Study.Stroke. 1996; 27: 1274-1282
- Leuko-araiosis.Arch Neurol. 1987; 44: 21-23
- Pathologic correlates of incidental MRI white matter signal hyperintensities.Neurology. 1993; 43: 1683-1689
- Pathophysiologic mechanisms in the development of age-related white matter changes of the brain.Dement Geriatr Cogn Disord. 1998; 9 Suppl 1: 2-5
- White matter changes in dementia of Alzheimer's type. Biochemical and neuropathological correlates.J Neurol. 1988; 111: 1425-1439
- MR signal abnormalities at 1.5 T in Alzheimer's dementia and normal aging.AJR. 1987; 149: 351-356
- White matter hyperintensities are a core feature of Alzheimer's disease: Evidence from the dominantly inherited Alzheimer network.Ann Neurol. 2016; 79: 929-939
- Subcortical ischaemic vascular dementia.Lancet Neurol. 2002; 1: 426-436
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Luo W AC, Albright J. The NeuroQuant Normative Database. Comparing Individual Brain Structures. In: Cortechs labs I, editor. San Diego, CA USA.
Published online: June 05, 2021
Accepted: April 24, 2021
Received: April 23, 2021
© 2021 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.