My husband has withdrawn & is not interested in doing anything. I am working from home & he disturbs me all day long. What can I do about his need for attention?

Of course your husband is wanting attention from you all day long as his brain is now forever broken and he doesn't know any better.
It's called shadowing and it is very common with someone with dementia. Perhaps like already mentioned hiring someone to keep him busy while your working or better yet taking him to an adult daycare center were he would be kept busy during his time there and let you get your work done. It would be a win win all the way around.
And yes of course education about this horrific disease will be your friend and let you know what lies ahead.
Wishing you well as you take this journey with your husband.

I would start with educating myself about the Alzheimer's and Dementia titles you have posted this under. Teepa Snow videos may be a good place to start.

Your husband suffers from Alzheimer's/dementia and depression according to your profile. Of course he wants your attention! Pick up a copy of the book Understanding the Dementia Experience by Jennifer Ghent-Fuller on Amazon so you can learn about dementia and how to deal with your husband's needs. If he interferes with your working schedule, either hire in home help or place him in Memory Care Assisted Living where he'll have activities and others to socialize with.

Good luck to you.

If you have enough money you can hire a companion aid to keep him entertained while you are working. Or, look into adult daycare.