How do you get someone screened for mental issues, depression, Alzheimer's or other dementias if they don't want it?

My husband has difficulties -- such as inability to tell the difference between an event next week vs. one 3 months in the future. He cannot make simple phone calls (i.e. to refill a prescription). He often can't find what he's looking for in the refrigerator. He DOES shower, shave, brush teeth, dress himself, stay current with TV news, yet he seems "absent" much of the time. For instance, we recently met with and hired someone to help with lawn care, but two hours later he didn't remember "shaking hands on the deal" and kept thinking we needed to call the man. I don't know whether he's not paying attention in the moment when events occur, or if it's a memory issue concerning recent events. I spend a lot of time explaining things to him, answering the same questions over & over. He also has anger issues -- is impatient, moody, accusatory, just plain mean. He complains all the time -- and I mean ALL THE TIME. He has Tourette-like vocalizations: makes anger sounds, misery sounds, wounded animal sounds, mumbles & grumbles, mutters under his breath. Yet I can't get him to agree to any kind of mental screening! I've been trying for years to get him to see a neurologist or psych, but no luck. How on earth do you get someone evaluated and into treatment???????