Prof Alex Leff
Professor of Cognitive Neurology
Neurotherapeutics Group Leader
Current Research and Interests
- Brain imaging studies of aphasia and alexia.
- Web-based therapies for patients with visual impairment or language impairment.
Lasting language dysfunction is among the most feared and disabling symptoms complicating stroke, yet there is little in the way of an evidence base for its treatment. This is because the mechanisms underpinning recovery from language disorders are not understood and trial interventions are generally not tested within rigorously designed studies. My work is aimed at filling in both these knowledge gaps simultaneously by combining modern trial-based methodology with functional imaging techniques so that the neural correlates of therapy driven recovery can be identified. My work is split between two common post-stroke syndromes: generalized language dysfunction (aphasia) and isolated reading dysfunction (alexia).
1. Acquired generalized language disorders (aphasia)
I have published several papers on the cortical regions involved in supporting speech perception in both normal subjects and patients with post-stroke aphasia. Supported by a Wellcome Trust Fellowship in Clinical Science, I am Chief Investigator on a trial of both a behavioural and drug (cholinergic) therapy in a group of patients with aphasia caused by stroke: Imaging the neural correlates of cholinergic and behaviour driven rehabilitation in patients with Wernickeâ??s aphasia. The aim of this project is to identify neural regions that correlate with therapy induced improvements in language function using functional Magnetic Resonance Imaging and Magnetoencephalography. The design is longitudinal, randomized, cross-over and double-blind (for the drug therapy).
2. Acquired isolated reading disorders (alexia)
The commonest type of alexia is hemianopic alexia (HA). It is caused by a right-sided homonymous hemianopia that interferes with text reading (in left-to-right readers); patients cannot plan their reading eye-movements efficiently across a line of text. My work to date has been on: a) characterizing the reading deficit in these patients (both in terms of behaviour and brain function); and, b) developing a community based behavioural therapy that produces a clinically meaningful, statistically significant improvement in text reading speed in the context of a controlled clinical trial. I have now made this therapy available for free on a website Read-Right: http://www.readright.ucl.ac.uk/ and have received a grant to further extend the diagnostic, therapeutic and research potential of this resource (Project grant from The Stroke Association: Web-based rehabilitation of hemianopic alexia). I am also supporting a trial of behavioural therapy for one of the other, rarer forms of peripheral alexia, pure alexia: Investigation of the rehabilitation of pure alexia using MEG.