An Early Report in this week's issue of THE LANCET outlines an imaging technique that could identify the early progression of Alzheimer's disease before the onset of clinical symptoms.
The early diagnosis and monitoring of the progression of Alzheimer's disease is important for the development of therapeutic strategies aimed at disease prevention. To detect the earliest structural brain changes, individuals need to be studied before symptom onset. Martin Rossor and colleagues from the National Hospital, London, UK, used an imaging technique (voxel-compression mapping) to localise progressive atrophy (brain-cell degeneration) in patients with preclinical Alzheimer's disease.
Four symptom-free individuals from families with early-onset Alzheimer's disease with known genetic (autosomal dominant) mutations underwent serial magnetic resonance imaging (MRI) over 5-8 years. All four developed symptomatic Alzheimer's disease during follow-up. 20 individuals with a clinical diagnosis of probable Alzheimer's disease and 20 control participants also underwent serial MRI.
Progressive atrophy was revealed in specific brain areas (posterior cingulate and neocortical temporoparietal cortical and medial temporal-lobe atrophy) in individuals before they had disease symptoms; in patients with known Alzheimer's disease, atrophy was widespread (apart from in the primary motor and sensory cortices and cerebellum).
Nick Fox, one of the investigators, comments: "Voxel-compression mapping provides a valuable technique for in-vivo monitoring of the progression of Alzheimer's disease. The ability to track physical disease progression in an individual patient from the earliest symptomatic stages has implications for the assessment of new treatments. We have been able to show a presymptomatic phase of 3 years or more of increased rates of tissue loss; the recognition of a presymptomatic phase which extends beyond the medial temporal lobe implies that structural changes might start earlier and are more widely distributed than previously appreciated. It raises the hope that we might one day be able to intervene with therapy at a very early stage, before the devastating cognitive decline of the disease has already become established."
Contact:Dr Nick Fox, Dementia Research Group, The National Hospital, 8-11 Queen Square, London WC1N 3BG, UK; T) +44 (0)20 7829 8773; F)+44 (0)20 7820 7132; E) firstname.lastname@example.org