Cognitive impairment and Charles Bonnet syndrome: a prospective study

Abstract

Objectives: Charles Bonnet syndrome (CBS) is a common cause of visual hallucinations in older people. The relationship between CBS and cognitive impairment is unclear, but anecdotal reports exist of dementia emerging in patients diagnosed with CBS. This work set out to determine if there is an increased incidence of dementia, and increased severity of cognitive impairment, in people with CBS compared to controls from the same clinical setting. Method: People over 65 attending low-vision and glaucoma clinics, and a cohort of age-matched controls, underwent a psychiatric assessment. The cohorts were followed up after one year. Results: Mild cognitive impairment was present in 2/12 CBS participants and 2/10 controls. Partial insight was seen in nine CBS participants. Two participants with CBS, and no controls, developed dementia at follow-up. No significant differences in performance on the ACE-R were found between the groups. Both participants who developed dementia had partial insight and hallucinations of familiar figures at diagnosis of CBS, and one had mild cognitive impairment. Conclusions: Reassurance that CBS is universally benign may be misplaced. Some people given this diagnosis go on to develop dementia. Cognitive testing at the point of diagnosis was unable to identify those at risk of this outcome. Partial insight, the presence of Mild Cognitive Impairment, and hallucinations of familiar figures at diagnosis of CBS may confer an increased risk of subsequent dementia diagnosis. Copyright # 2017 John Wiley & Sons, Ltd. IntroductionCharles Bonnet syndrome (CBS) was introduced to the medical literature nearly 80 years ago by a Genevan neurologist, Georges de Morsier (de Morsier, 1936). Its name refers to a fellow resident of Geneva, the natural philosopher Charles Bonnet, who gave a detailed description of the visual hallucinations experienced by his grandfather (Bonnet, 1760). In de Morsier's original definition, the syndrome was intended to denote visual hallucinations in elderly people with intact mental functioning. Subsequently, authors have defined CBS on phenomenological grounds, stressing the key features as being formed, complex, persistent visual hallucinations, occurring with insight, and without delusions or hallucinations in other modalities (Damas-Mora et al., 1982;Gold and Rabins, 1989). The most recent review of these criteria was in 1996 (Teunisse et al., 1996), and these operationalised criteria are set out in Table 1. The criteria allow for the diagnosis to be made in cases where insight is partial, reflecting the finding that in many cases there is an initial period of deception where the hallucinations are accepted as real (Menon et al., 2003;Menon, 2005).The exclusion from the CBS diagnosis of patients who lack insight into the nature of the hallucinations RESEARCH ARTICLE means that patients with established dementia are unlikely to meet diagnostic criteria for CBS. However, the expansion of the criteria to allow for cases where insight was partial raises the potential for there to ...

Resting-state functional connectivity and cortical thickness characterization of a patient with Charles Bonnet syndrome

“…CBS symptoms can last for many years and have negatives consequences in around a third of CBS population [51], thus a better understanding of this pathology might enhance the healthcare provided to this population and their quality of life. From a clinical perspective, a better understanding of this syndrome is essential since, for example, a recent study suggests that patients with CBS may present an increased risk of subsequently developing dementia, when combined with Mild Cognitive Impairment and partial impairment of insight [52]. Indeed, so far the interpretation of the connectivity changes, as well as their clinical significance, is still not understood.…”

Hallucinatory Experiences in Visually Impaired Individuals: Charles Bonnet Syndrome – Implications for Research and Clinical Practice

“…In some cases after a complete visual loss, the condition might improve spontaneously ( . Several studies indicate that some of patients with CBS may develop dementia latter on and thus, recommendations are to emphasize frequent neurologic monitoring in order to detect cognitive impairments as early as possible (Pliskin et al 1996, Lapid et al 2013, Russell 2017.Use of atypical antipsychotic medications (olanzapine, quetiapine, risperidone) showed different success, where anticonvulsants (clonazepam, valproate, carbamazepine) were useful only in selected cases (Boller et al 2018). It is regarded that atypical and even more so typical antipsychotic medications should be avoided as much as possible because of the side effects in elderly patients.…”

Hallucinations in Healthy Older Adults: An Overview of the Literature and Perspectives for Future Research

“…For instance, there has been an ongoing debate as to whether visual hallucinations in Charles Bonnet Syndrome are, or are not, an early risk marker for dementia (Pliskin et al, 1996; Lapid et al, 2013). However, recent prospective data from Russell et al (2017) point to an increased incidence of dementia in people over 65 with this syndrome. On the other hand, minor hallucinations are reported in 42% of new, untreated cases of Parkinson's disease (Pagonabarraga et al, 2016), with early evidence of visual hallucinations predicting an increased risk of dementia (ffytche et al, 2017).…”