Ccaring ofr someone with dementia, is probably the hardest row you can hoe when in old age, especially when the person cared for is someone who is so dear and the only way is down, but I think your experience of men with it at such a young age is unusual.
Dementia, unless there is an occupational or life style reason, tends to be a disease of extreme old age, hence Oopsadaisy's experience, which is mine as well, both when I worked for a charity for the aged and when I cared for an aunt and uncle, both with dementia. My uncle was one of the few men in the care home and the average age for all residents was over 85. I heard yesterday that a male friend has just been diagnosed in the early stages of dementia. He, again, is over 85.
All of this can be no consolation to you, living as a carer for someone who has been diagnosed with this disease so young.