Lilamutton,
Alzheimer's is just one cause of dementia. However, Familial Alzheimer's disease (FAD) or Early onset Familial Alzheimer's disease (EOFAD) is an uncommon form of Alzheimer's disease that usually strikes earlier in life, defined as before the age of 65 (usually between 50 and 65 years of age, but can be as early as 15) and is inherited in an autosomal dominant fashion, identified by genetics and other characteristics such as the age of onset. It accounts for approximately half the cases of early-onset Alzheimer's disease. For a diagnosis of early onset Alzheimer's, the patient must have at least one first degree relative with Alzheimer's disease.
For early onset Alzheimer's there is genetic testing that can be done. You might look into that. However, with the symptoms and the first degree relative, it may not be necessary. If your husband does not have a neurologist, you may need to arrange for him to be seen by one.
Good luck.