Doris* (name changed) realised her husband was an alien 5 months ago. An alien clone to be precise: who spoke, dressed and acted exactly like her husband, but was not the man she married.
I met Doris on a home visit as part of my four-year medical attachment in Elderly Psychiatry. She greeted the community nurse and I with a warm smile and offered us stale biscuits and warm tea. Having been diagnosed with dementia nearly 10 years ago, Doris appeared a bit scattered. She’d lost chunks of her memory and flicked between eras randomly.
It was when Doris started justifying her belief that her husband was an alien by getting me to feel his cold hands that I realised I had no clue what was going on. Doris had gone far beyond what we had been taught was ‘normal’ for a person with dementia. It wasn’t until later, when I was in the car with the nurse, that I discovered what was happening. Doris has developed the extremely rare but fascinating ‘Capgras delusion’.
Sufferers of the psychiatric illness Capgras are convinced that those close to them have been replaced by identical imposters. Such delusions (abnormal fixed beliefs) are commonly associated with dementia, but can also be found in stroke or schizophrenia cases.
As with all of psychiatry, there are many theories floating around about the cause of Capgras; however, only one is widely respected. Ramachandran’s ‘theory of dissociation’ suggests that people with Capgras can recognise the faces of loved ones perfectly but cannot relate the faces to the emotional centres of their brain.
So Doris recognises her husband as someone she should know and thus has stored emotions relating to him (love/hate/anger etc.). The lack of emotions but the familiar face forces the brain to come to a strange (but logical) conclusion – that this man is just someone who looks like her husband and that is why she feels nothing when she sees him.
Capgras is a beautifully tragic condition with unfortunately no decent treatment. Before I left, I asked Doris how she coped with the belief that her husband was a Martian imposter. She reached into her purse and placed a torn photograph in my hand: a fresh, bright, young couple stepping out of a church door, confetti raining down on them from unseen hands, “He’ll come back.”