My 90-year old husband is becoming paranoid. Is that normal?

Paranoia is not normal, ever.
It is common in dementias.
It also could be medications he's on, not working right in his system [bad side effects].
It also can be related to things changed in his environment, including chemicals like laundry or cleaning products, exhaust fumes coming in the air ducts, etc.
I've even heard of someone dosing an elder with hallucinogenic drugs, causing it.

There might be medications and/or nutritional things that could help.
If it is related to something in his environment, which can be changed, that could help.

Please check with his Doctor, and maybe do some simple sleuthing of the environment he's usually in just before or during the paranoia episodes.

It is common with Alzheimer's that people become paranoid, but again, paranoia is not a normal condition. First off check his vitamin B levels, then have his thyroid checked. If those two come out normal then have a full metabolic panel. He could be diabetic or have any number of conditions that would cause this that are treatable, If all tests come out normal then call in the big guns. Prescription drugs are a last resort in my mind. Good nutrition is first.

Anyone can be paranoid not just a 90 yr old .nothing psychological is normal .
I 'm sure there are meds to help control it .He must be going through h*ll with it .
Sorry he's in that situation .poor guy .

Paranoia is not normal, but VERY common with Demenia. There are meds that really help. You just need to get an Rx.

Any new symptom, physical or psychological, should be reported and discussed with his Dr. If your husband is 90 and you're just now noticing paranoia creeping up that's not normal.

Paranoia is never normal. Share your experiences with his MD.