Objectives: To highlight the importance of differential diagnosis in the psychogeriatric context, with an emphasis on Lewy Body Dementia (LBD).

Case Report: A 68-year-old woman with 6 years of education presented with symptoms of hypobulia, social withdrawal, sadness, and anhedonia 10 years ago. Concurrently, she experienced delusions and visual hallucinations, believing that armed neighbors were entering her house to kill her. She began psychiatric treatment at the Geriatric Psychiatry department at UNIFESP, where she was diagnosed with depressive disorder with psychotic symptoms and panic disorder. She was started on sertraline, and due to QT interval prolongation with risperidone and quetiapine, clozapine 100mg was introduced, without extrapyramidal signs and symptoms She experienced remission of visual hallucinations but developed apathy but started to exhibit periods of mental confusion. During follow-up, cognitive impairment was noted, and a diagnosis of dementia was made. She began forgetting to turn off the stove, leaving doors open, and getting lost in unfamiliar places. MRI of the brain (2017) showed diffuse bilateral atrophy, and SPECT (2018) showed diffuse (non-localized) hypoperfusion, as per medical records. The attending team referred her for joint evaluation, suspecting frontotemporal dementia and behavioral variant Alzheimer’s disease due to observed apathy and behavioral changes. She was referred for follow-up at the Behavioral Neurology Clinic at UNIFESP. The patient was evaluated by behavioral, sleep, and extrapyramidal neurology clinics. All concurred on the most probable diagnosis of Lewy body dementia (LBD), characterized initially by well- defined visual hallucinations of deceased relatives interacting with her, significant movement during sleep with vocalization and dream enactment, rigidity, gait instability that worsened with antipsychotic treatment, episodes of inattention, and marked apathy. Cognitive fluctuation was noted by her husband and confirmed by the application of the MMSE in different consultations. Galantamine 24mg was prescribed, leading to initial improvement in cognitive complaints at the start of treatment.

Discussion: Lewy Body Dementia is the second most common neurodegenerative disease causing dementia. It is believed to be vastly underdiagnosed, with a significant disparity between the number of clinically diagnosed cases and those diagnosed via neuropathology at postmortem autopsy. According to a study conducted by Auning E et al., which differentiated the presenting complaints of DLB and AD, the most common complaint reported by DLB patients was memory dysfunction, with a prevalence of 57%, followed by visual hallucinations (44%), depression (34%), problem-solving difficulties (33%), gait disturbances (28%), and tremor and stiffness (25%), all features presented by the patient in this case report.

Conclusions: Specificity and diagnostic accuracy in the clinical setting remain challenges in the diagnosis of DLB. In the clinical setting, DLB is often misdiagnosed.