Bill Gates has pledged to invest $100 million (£76 million) into research to find a breakthrough for Alzheimer's disease.

The billionaire, who is the richest person on the planet, announced yesterday he plans to make an initial $50 million (£38 million) investment into a venture capital fund, Dementia Discovery Fund, that finances new treatments for the degenerative condition.

This is due to be followed up by another $50 million investment in start-up ventures working in research on Alzheimer’s, which currently has no cure.

The Microsoft co-founder said he was partly moved to make the huge investment by his personal experience of the disease that has affected men in his family.

In a blog post, he wrote: “I know how awful it is to watch people you love struggle as the disease robs them of their mental capacity, and there is nothing you can do about it. It feels a lot like you’re experiencing a gradual death of the person that you knew.”

However he added he was also motivated by the fact Alzheimer's is the only disease in the top ten causes of death in his native US that doesn't have a meaningful treatment.

Without a breakthough treatment, Mr Gates warned the condition would put an increasing strain on healthcare systems around the world as populations aged.