快猫短视频

A shock of electricity to the temples can be a powerful, last-resort treatment for some people who have mental health conditions that don鈥檛 respond to other treatments. But it can have surprising side effects 鈥� it seems to have improved the colour vision of a woman with colour blindness in the hours after each treatment.

Electroconvulsive therapy (ECT) can be recommended for people with severe depression, schizophrenia or mania. The procedure typically involves giving someone anaesthesia and a muscle relaxant, before applying a pulse of electric current to one or both sides of the head. The pulse lasts for between 6 and 8 seconds, during which time it triggers brain seizures, says Kristian H. Reveles Jensen at the Psychiatric Centre Copenhagen in Denmark.

Jensen and his colleagues offered this treatment to a 30-year-old woman experiencing severe symptoms of post-natal depression. Since the woman had given birth six months previously, she had been experiencing symptoms of depression. Group therapy, speech therapy and anti-depressant drugs didn鈥檛 improve her symptoms, and the woman was hospitalised when she started having suicidal urges.

Even then, she continued to deteriorate, says Jensen. 鈥淪he was experiencing sleep disturbance, low mood, shame, feelings of inadequacy 鈥� the classic symptoms of depression,鈥� he says. 鈥淪he was in quite a lot of distress.鈥�

Red berries

The woman accepted the offer of ECT, and underwent a series of treatments. After her sixth, she mentioned in passing to one of the nurses that her colour vision seemed to have changed. The woman, who was red-green colour blind, said she was able to pick out red berries in a green bush for the first time, says Jensen.

The effect was only temporary. After a morning treatment, the woman could experience these colours in the afternoon and evening. But when she woke up the next morning, she once more found it difficult to distinguish red and green, says Jensen.

To find out if the woman鈥檚 colour perception was changing in a measurable way, Jensen and his colleagues administered a classic test for red-green colour blindness. The Ishihara test involves presenting images made up of coloured dots in shades of red and green, and asking a person to pick out a pattern among the dots.

Definitely surprising

When the woman was tested before an ECT treatment, she made 30 mistakes out of a possible 36. But in the hour following a treatment, she made 15 mistakes. 鈥淚t was definitely surprising,鈥� says Jensen. 鈥淚鈥檇 never heard of this.鈥�

Jensen and his colleagues aren鈥檛 sure how the change in colour perception is occurring. Colour blindness is caused by a lack of cones 鈥� cells in the retina that are responsible for colour vision. ECT won鈥檛 give people new cone cells.

But it might change the way signals from these cells are perceived by the brain. ECT treatments can change the level of a range of neurotransmitters in the brain, and seem to encourage the growth of new neurons, so it is likely to change the way brain cells communicate, says George Kirov at Cardiff University, UK. 鈥淐olours do not exist really,鈥� says Kirov. 鈥淚t鈥檚 what the brain makes up from the signals it receives.鈥�

It is also possible that treating the woman鈥檚 depression was enough to change her perception of colour. People with depression can find it difficult to concentrate, and to pick out fine details in images, and some report seeing the world in greys and muted tones.

ECT was successful at treating the woman鈥檚 depression, so may have alleviated this symptom to some degree, says Jensen. The effect was probably more pronounced in the hours following treatment because this is when many people experience an 鈥渁fterglow鈥� effect 鈥� a period of especially heightened mood after a treatment, says Jensen.

鈥淪ometimes we do see spikes in mood for a time just after ECT,鈥� says Kirov.

鈥淎 lot of [my patients] prefer to have treatments on Fridays, because then they鈥檙e guaranteed a good weekend,鈥� says Jensen.