Cognitive Decline After Stroke

This article was originally published by the BHRC [http://www.otago.ac.nz/bhrc/news/otago629705.html]

Stroke is one of the leading causes of death and disability in the developed world. Around 5 million people are permanently disabled by stroke every year and new research, from Dr Andrew Clarkson, demonstrates that the damage caused to the brain is not all immediate.

Stroke is caused by a blockage or bleed from a blood source in the brain. The area which is immediately affected by this change to blood supply experiences severe cell death, resulting in an actual hole being created in the brain. Over the days following a stroke this hole grows, and the disabling effects of the stroke can become worse. However, Dr Clarkson and his team found that the effects can keep getting worse even after the area affected by the stroke has stopped growing.

Your brain is intricately interconnected. Each cell can be connected to hundreds or thousands of other cells, working together toward a variety of aims. When an individual has a stroke and they experience cell death they’re not just losing the functions of the cells that die, but also some of the functions of the cells which connected to those now dead cells. This can cause knock-on effects which result in a worsening of symptoms even though the obvious injury has stopped growing.

Dr Clarkson and his team looked at the effect of a stroke in the prefrontal cortex on a number of functions, testing them one week and four weeks after the stroke had occurred. They found that spatial memory, our memory of where an object is located in space, was significantly worse at four weeks than it had been at one week. This shows that the individual is still losing function weeks after the actual stroke.

This could be due to brain-wide changes which occur as the rest of the brain tries to take up the role of those now-dead cells, or it could be because as a result of cell-death some circuits just aren’t being maintained and so they begin to deteriorate as time goes on.

The study confirms reports gathered from stroke victims, and provides greater information of what to expect after a stroke. It also reinforces the importance of rehabilitation for those recovering from stroke, to minimise the chance of further damage as time goes on. Knowledge is crucially important for the management, treatment, and rehabilitation of stroke and this work ensures that individuals can be more prepared for the after-effects of this life-altering event.

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