Use of 31 P magnetisation transfer magnetic resonance spectroscopy to measure ATP changes after 670 nm transcranial photobiomodulation in older adults

Mitochondrial function declines with age, and many pathological processes in neurodegenerative diseases stem from this dysfunction when mitochondria fail to produce the necessary energy required. Photobiomodulation (PBM), long-wavelength light therapy, has been shown to rescue mitochondrial function in animal models and improve human health, but clinical uptake is limited due to uncertainty around efficacy and the mechanisms responsible. Using 31 P magnetisation transfer magnetic resonance spectroscopy (MT-MRS) we quantify, for the first time, the effects of 670 nm PBM treatment on healthy ageing human brains. We find a significant increase in the rate of ATP synthase flux in the brain after PBM in a cohort of older adults. Our study provides initial evidence of PBM therapeutic efficacy for improving mitochondrial function and restoring ATP flux with age, but recognises that wider studies are now required to confirm any resultant cognitive benefits.

Localizing Sites of Activation in Primary Visual Cortex Using Visual-Evoked Potentials and Functional Magnetic Resonance Imaging

This study compared retinotopic map identification in primary visual cortex (V1) using: (i) functional magnetic resonance imaging (fMRI) and (ii) visual evoked potentials (VEPs) coupled with dipole source localization (DSL). A multielectrode array was used to record VEPs while subjects viewed a flickering dartboard pattern modulated by a 16-bit m-sequence. The stimulus preferentially activates V1. Using a common time function DSL algorithm, the primary source of each stimulus patch was found independent of the fMRI. The VEP/DSL and fMRI localization data for each subject were aligned by a rigid translation and rotation. The average distance between VEP and corresponding fMRI sources was 10.8 mm +/- 3.8 mm. To assess the significance of the results, fMRI and DSL solutions were scrambled so the comparisons were no longer for corresponding patches. The average distance between the noncorresponding data sets was 17.2 mm for 50 million scrambles. The probability of the scrambled data yielding a better fit than the real data was p < 10(-7). The combination of multielectrode recording, multiinput visual stimulation and common time function DSL analysis can provide a detailed retinotopic map of visual cortex that has high correspondence with independent fMRI localization analysis on the same subject.

[Canthaxanthin retinopathy. Follow-up of over 6 years]

After long-term treatment with high dosages, canthaxanthin causes a characteristic retinopathy with circular, macula surrounding crystals. As changes in retinal functionning disappear relatively easily after withdrawal of the drug, the crystals dissolve rather slowly--over about several years. Five patients showing a profound crystalline retinopathy were re-examined with an average of 69.7 months after withdrawal of the canthaxanthin-containing drug. Three of the patients were treated for erythropoetic protoporphyria (EPP) with Phenoro (2/5 beta-carotene, 3/5 canthaxanthin), two sisters took a canthaxanthin-containing formulation (1/8 beta-carotene, 7/8 canthaxanthin) for cosmetic reasons. Two female patients complained about an increased glare sensitivity, which was explainable for one of them with a subcapsular cataract. The retinal crystals decreased quite differently. Minor deffects of the retinal pigment epithelium remained unchanged in two patients. They increased slightly in the female patient with the smallest crystal formation but highest plasma cholesterol. Shortly after withdrawal of the drugs usually an increase of a-wave amplituded of the electroretinograms was found. The a-waves returned to normal and the b-wave amplitudes showed an increase up to the final control paralleling the reduction of the retinal crystals. A- and b-wave peak latencies which were prolonged under treatment returned to normal.