Two-year longitudinal follow-up of visual illusions and hallucinations in Parkinson's disease.

BACKGROUND: Previous longitudinal studies assessing visual hallucinations in Parkinson's disease (PD) have not specifically considered the respective evolution of visual illusions (VI) and visual hallucinations (VH), neither did they assess the role of ocular pathology on the evolution of those manifestations. OBJECTIVE: We aimed to determine whether VI evolve towards VH along the time in PD, and whether ophthalmological treatment may have a positive effect on the prognosis of those visuo-perceptive manifestations. METHODS: PD patients from a previous cohort [PD with VI (n = 26), PD with VH (n = 28), and PD without VI or VH (n = 28)] were contacted by phone 2 years later and questioned regarding the current presence of VI or VH, any current visual complaints, and the occurrence of any ophthalmological or antipsychotic treatment during the 2-year period, as well as any dopatherapy adjustment. RESULTS: Among PD-VI patients, 43% normalized, 48% remained PD-VI, 9% evolved towards coexisting VI and VH, and none converted to pure VH. Among PD-VH patients, 42% normalized, 32% remained PD-VH, 21% evolved towards coexisting VI and VH, and only 5% converted to pure VI. At follow-up, visual complaints remained greater among PD-VI and PD-VH compared to controls (p = 0.005). Among PD-VI and PD-VH who became control at follow-up, 35% received ophthalmologic treatment, 29% antipsychotic treatment, and 23% a dopatherapy reduction. CONCLUSION: PD Patients with VI do not necessarily evolve towards VH over time, and ophthalmological treatment may have a positive effect on the prognosis of those visuo-perceptive manifestations in PD similar to antipsychotic treatment and dopatherapy adjustment. TRIAL REGISTRATION: clinicaltrials.gov number NCT01114321.

Structural and Functional Correlates of Hallucinations and Illusions in Parkinson's Disease.

BACKGROUND: Visual illusions (VI) in Parkinson's disease (PD) are generally considered as an early feature of the psychosis spectrum leading to fully formed visual hallucinations (VH), although this sequential relationship has not been clearly demonstrated. OBJECTIVE: We aimed to determine whether there are any overlapping, potentially graded patterns of structural and functional connectivity abnormalities in PD with VI and with VH. Such a finding would argue for a continuum between these entities, whereas distinct imaging features would suggest different neural underpinnings for the phenomena. METHODS: In this case control study, we compared structural and resting state functional MRI brain patterns of PD patients with VH (PD-H, n = 20), with VI (PD-I, n = 19), and without VH or VI (PD-C, n = 23). RESULTS: 1) PD-H had hypo-connectivity between the ILO and anterior cingulate precuneus and parahippocampal gyrus compared to PD-C and PD-I; 2) In contrast, PD-I had hyper-connectivity between the inferior frontal gyrus and the postcentral gyrus compared to PD-C and PD-H. Moreover, PD-I had higher levels of functional connectivity between the amygdala, hippocampus, insula, and fronto-temporal regions compared to PD-H, together with divergent patterns toward the cingulate. 3) Both PD-I and PD-H had functional hypo-connectivity between the lingual gyrus and the parahippocampal region vs. PD-C, and no significant grey matter volume differences was observed between PD-I and PD-H. CONCLUSION: Distinct patterns of functional connectivity characterized VI and VH in PD, suggesting that these two perceptual experiences, while probably linked and driven by at least some similar mechanisms, could reflect differing neural dysfunction.

Visual hallucinations and illusions in Parkinson's disease: the role of ocular pathology.

INTRODUCTION: Whether different mechanisms, particularly ocular pathology, could lead to the emergence of visual hallucinations (VH) (defined as false perceptions with no external stimulus) versus visual illusions (VI) (defined as a misperception of a real stimulus) in Parkinson's disease (PD) remains debated. We assessed retinal, clinical and structural brain characteristics depending on the presence of VH or VI in PD. METHODS: In this case-control study, we compared retinal thickness using optical coherence tomography (OCT), between PD patients with: VI (PD-I; n = 26), VH (PD-H; n = 28), and without VI or VH (PD-C; n = 28), and assessed demographic data, disease severity, treatment, anatomical and functional visual complaints, cognitive and visuo-perceptive functions and MRI brain volumetry for each group of PD patients. RESULTS: Parafoveal retina was thinner in PD-H compared to PD-C (p = 0.005) and PD-I (p = 0.009) but did not differ between PD-I and PD-C (p = 0.85). Multivariate analysis showed that 1/retinal parafoveal thinning and total brain gray matter atrophy were independently associated with the presence of VH compared to PD-I; 2/retinal parafoveal thickness, PD duration, sleep quality impairment and total brain gray matter volume were independent factors associated with the presence of VH compared to PD-C; 3/anterior ocular abnormalities were the only factor independently associated with the presence of illusions compared to PD-C. CONCLUSION: These findings reinforce the hypothesis that there may be different mechanisms contributing to VH and VI in PD, suggesting that these two entities may also have a different prognosis rather than simply lying along a continuous spectrum. REGISTRATION NUMBER: Clinicaltrials.gov number NCT01114321.