Results

Demographic and clinical findings are shown in table 1. There was a high prevalence of formed visual hallucinations, consisting of people or animals. Auditory hallucinations were relatively rare. Delusions were predominantly linked to patients' visual hallucinations, consisting of false belief of people having entered the home. However, they also comprised paranoid ideation, including the belief that someone wished to kill them, delusions of infidelity, belief that their spouse was an impostor (Capgras delusion) and that the family home was duplicated (reduplicative paramnesia). Thirty-three patients exhibited hallucinations without delusions whereas only four patients exhibited delusions without hallucinations, in two cases this constituting Capgras delusion.

In 100/102 patients (98%) no repeat expansions in the C9ORF72 gene were found (median repeats 3, range 1–25). Expansions (>30) were detected in two patients (2%).

Patient 1 presented with gradual decline in memory, expressive language, calculation and visuospatial skills aged 60 years. She became lost in familiar surroundings, could no longer cook or operate household gadgets. Behaviour and affect were unchanged, aside from a false belief that neighbours were taking part in television programmes. No hallucinations were reported. Neurological examination revealed amimia, limb rigidity and resting tremor, but no weakness, wasting or fasciculations. Neuropsychological examination revealed performance fluctuations. There were impairments in language, perception, spatial skills, memory (with confabulation and interference) and executive skills. An MRI scan showed generalised atrophy, single-photon emission CT scan parietal hypoperfusion and EEG delta activity. She became increasingly parkinsonian and tremulous. Her sleep pattern was disrupted. She was prescribed cholinesterase inhibitors, leading to some improvement. There was a previous medical history of an acute onset of aphasia and limb weakness, ascribed to a stroke. These symptoms had apparently resolved prior to the onset of her progressive illness. There was no family history of dementia or other neurodegenerative disease.

Patient 2 presented with gradual mental and physical slowing aged 69 years. His gait was shuffling, his hands trembled and his voice was hypophonic. Speech content was rambling and off the point. His personality was retained and he exhibited no stereotypic behaviours or altered eating habits. During a routine hospital admission he suffered an acute confusional episode lasting several days in which he became deluded and hallucinated. He believed he was being poisoned and that there were criminal activities taking place on the ward. He saw animals and puppets. There was no relevant previous medical or family history. Neurological examination revealed parkinsonism, but no wasting or fasciculations. Neuropsychological examination revealed performance variability, with fluctuations of attention and distractibility. Mild deficits were elicited in spelling, calculation, visual perception, spatial and constructional skills. Confrontation naming, word and sentence comprehension and repetition were preserved. He had a normal span of eight digits. There was no gestural apraxia. Memory recall was poor and on story recall he misconstrued the thematic content. However, he was well oriented, recognition memory was intact with no abnormal information loss over a delay. Executive tests elicited poor sequencing and a mild perseverative tendency, but preserved abstraction and mental set shifting. Category and letter fluency performance was within normal limits. Motor responses were slowed. A CT scan showed generalised cerebral atrophy. He was lost to follow-up.