Vision loss and hallucinations: perspectives from neurology and ophthalmology

Approach to Vision Loss

OBJECTIVE

Diagnosing and differentiating among the many possible localizations and causes of vision loss is an essential skill for neurologists. This article outlines the examination of the eye and visual pathways and the differential diagnosis of pathophysiologic processes that can affect visual function.

LATEST DEVELOPMENTS

The eyes, optic nerves, and intracranial pathways of vision account for more than one-third of the volume of the human brain, and patients with vision loss are commonly seen by both eye care specialists and neurologists. A basic examination of the eye and visual pathways allows the neurologist to localize the abnormality causing the vision impairment and generate a differential diagnosis of the potential pathophysiologic processes that can cause a vision problem at that particular location. Neurologists should be aware of the many ocular causes of vision loss and recognize when a visual problem is not the result of an optic neuropathy or brain parenchymal lesion. The standard bedside examination of the visual system can be augmented using specialized ancillary testing of visual pathway structure and function, which is most often the purview of eye care specialists, although portable instruments such as small visual field machines and nonmydriatic ocular fundus imaging can be easily used in hospitals and neurology clinics.

ESSENTIAL POINTS

The approach to vision loss should include a history and examination geared toward localization, followed by a differential diagnosis based on the likely location of the pathophysiologic process. Coordinated care between neurologists and eye care specialists is essential for patients with optic neuropathy or other lesions of the intracranial pathways.

Association of Visual Impairment With Neuropsychiatric Symptoms of Dementia

BACKGROUND

Visual impairment is a risk factor for cognitive impairment and hallucinations in older adults, but associations with other neuropsychiatric symptoms (NPS) of dementia have not been examined.

METHODS

We analyzed cross-sectional data from the Aging, Demographics, and Memory Study (ADAMS), a nationally representative sample of the US population aged 70+ years. Vision was measured by self-report and using a near card. Dementia was ascertained through cognitive testing with expert consensus, and NPS were screened using the Neuropsychiatric Inventory. We used logistic regression to measure the association between visual impairment and prevalent NPS adjusting for sociodemographic factors and comorbidities. Analyses incorporated sample weights to account for the complex survey design of ADAMS.

RESULTS

Of 624 participants with dementia, 332 (53%) had self-reported visual impairment and 193 (31%) had best-corrected acuity of 20/40 or worse. In unadjusted models, self-reported visual impairment was significantly associated with hallucinations (OR 2.88; 95% CI 1.12-7.44), depression (OR 2.79; 95% CI 1.7-4.57), and agitation (OR 1.61; 95% CI 1.05-2.48). Reduced visual acuity was associated with hallucinations (OR 10.13; 95% CI 2.93-34.98), psychosis (OR 6.69, 95% CI 2.53-17.7), and mania (OR 5.92, 95% CI 1.77-19.82). However, these associations did not remain significant after covariate adjustment.

CONCLUSIONS

Visual impairment was associated with hallucinations, depression, agitation, psychosis, and mania in patients with dementia, but at least some of this relationship is explained by age, comorbidities, and other factors.

A Longitudinal Perspective Case Study of Delusional Parasitosis in a Geriatric Psychiatry Unit

Delusional parasitosis is not a common presentation in hospital-based geriatric units. Our aim was to review the presentation of a sudden onset of parasitosis in an older patient who had no prior psychiatric history, and its management. This case report describes an 82-year-old man who presented with delusions of parasitosis for the past three years of his life. The report includes a longitudinal description of the patient's symptoms, signs, and manifestations during his stay at an inpatient senior mental health service center, emergency department (ED) visits, and medical floor stay along with medication management of his psychiatric symptoms with concomitant medical issues. Presentation of delusional parasitosis poses a special challenge not only psychiatrically but also medically and dermatologically. The unique difficulty of finding appropriate antipsychotics for not only the symptoms of parasitosis but also the compulsive behavior that follows a deeply ingrained belief of being infested must be carefully managed, especially in the elderly. Somatic delusions that resemble a plausible but inaccurate reality of infestations could delay treatment as well.

Medicare Claims Data Underestimate Hallucinations in Older Adults With Dementia

OBJECTIVE

Administrative claims data are used to study the incidence and outcomes of dementia-related hallucinations, but the validity of International Classification of Diseases (ICD) codes for identifying dementia-related hallucinations is unknown.

METHODS

We analyzed Medicare-linked survey data from 2 nationally representative studies of U.S. older adults (the National Health and Aging Trends Study and the Health and Retirement Study) which contain validated cognitive assessments and a screening question for hallucinations. We identified older adults who had dementia or were permanent nursing home residents, and we combined this with questionnaire responses to define dementia-related hallucinations. Using Medicare claims data, we calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ICD codes for dementia-related hallucinations overall and within prespecified strata of age, neurologic comorbidity, and health care utilization.

RESULTS

We included 2,337 older adults with dementia in our cohort. Among 3,789 person-years of data, 1,249 (33.0%) had hallucations, and of these 286 had a qualifying ICD code for dementia-related hallucinations or psychosis (sensitivity 22.9%). Of 2,540 person-years of dementia without hallucinations, 284 had a diagnosis code for hallucinations (specificity 88.8%). PPV was 50.2%, and NPV was 70.1%. Sensitivity was greatest (57.0%) among those seeing a psychiatrist. Otherwise, there were no significant differences in sensitivity, specificity, PPV, or NPV by age, neurologic diagnosis, or neurologist care.

CONCLUSION

Dementia-related hallucinations are poorly captured in administrative claims data, and estimates of their prevalence and outcomes using these data are likely to be biased.