We aimed to investigate the association between very late-onset schizophrenia-like psychosis (VLOSLP), a schizophrenia spectrum disorder with an onset of ≥60 years, and Alzheimer’s disease (AD) using biomarkers.

Retrospective cross-sectional study.

Neuropsychology clinic of Osaka University Hospital in Japan.

Thirty-three participants were classified into three groups: eight AD biomarker-negative VLOSLP (VLOSLP−AD), nine AD biomarker-positive VLOSLP (VLOSLP+AD), and sixteen amnestic mild cognitive impairment due to AD without psychosis (aMCI−P+AD) participants.

Phosphorylated tau levels in the cerebrospinal fluid and 18F-Florbetapir positron emission tomography results were used as AD biomarkers. Several scales (e.g. the Mini-Mental State Examination (MMSE), Wechsler Memory Scale-Revised (WMS-R) Logical Memory (LM) I and II, and Neuropsychiatric Inventory (NPI)-plus) were conducted to assess clinical characteristics.

Those in both VLOSLP−AD and +AD groups scored higher than those in aMCI−P+AD in WMS-R LM I. On the other hand, VLOSLP+AD participants scored in between the other two groups in the WMS-R LM II, with only VLOSLP−AD participants scoring significantly higher than aMCI−P+AD participants. There were no significant differences in sex distribution and MMSE scores among the three groups or in the subtype of psychotic symptoms between VLOSLP−AD and +AD participants. Four VLOSLP−AD and five VLOSLP+AD participants harbored partition delusions. Delusion of theft was shown in two VLOSLP−AD patients and five VLOSLP+AD patients.

Some VLOSLP patients had AD pathology. Clinical characteristics were different between AD biomarker-positive and AD biomarker-negative VLOSLP, which may be helpful for detecting AD pathology in VLOSLP patients.

The large proportion of patients with late-onset schizophrenia (LoS) has cognitive impairment. We hypothesized that this group of patients could have more risk factors associated with neurodegeneration.

The aimed to compare various clinical and risk factors in LoS patients with low and relatively preserved cognitive status.

28 LoS patients (ICD-11) with duration of disease less than 10 years from a cohort of patients with late onset psychosis underwent clinical assessment (PANSS, HDRS-17), cognitive examination (MMSE, MoCA, FAB, verbal and symbolic memory, trail making test (part A, B)), structured interviewing on risk factors and CT. Hierarchical cluster analysis of cognitive test results was applied. Nonparametric statistic was used to compare control group (24 subjects with signs of psychosis or depression, age 58,1±10,8, 50% females) and patient`s groups.

Patients were divided on two clusters: Cluster 1 with lower cognitive functions (n=20, age 62,2, 94% of females) and Cluster 2 with preserved cognitive functions (n=8, age 56,8, 100% of females). Patients of Cluster 1 were older, had more negative symptoms, higher atrophy scores, higher rate of leukoaraiosis on CT and more history of mild brain injury than patients of Cluster 2 and controls. There was no group differences in age of manifestation, other PANSS scores, rates of social phobia and number of habitual anxiety reactions between clinical groups.

LoS patients with cognitive deficiency had more factors associated with neurodegeneration, in particular history of mild brain injury.

No significant relationships.

According to the literature, cognition may be more preserved in late-onset schizophrenia (LOS) compared to early-onset schizophrenia (EOS), but data are limited.

To compare performance on cognitive tests in LOS and EOS.

LOS patients (n=14, mean age 58.1±8.2, 13 females, illness duration 1.07±1.5 years) and age-comparable controls (n=17, mean age 55.3±7.8, 12 females), EOS patients (n=25, mean age 20.7±3.9, 25 males, illness duration 0.75±0.62 years) and age-comparable controls (n=15, mean age 22.9±2.3, 15 males) underwent the Brief Assessment of Cognition in Schizophrenia (BACS) comprised of six subtests: Verbal Memory, Digit Sequencing, Verbal Fluency, Token Motor Task, Symbol Coding, and Tower of London. The Mann-Whitney U test with Bonferroni correction for multiple comparisons was applied (p <.05/8, i.e. p <.006).

Compared to LOS, EOS patients had lower score on Verbal Fluency (VF): U=78, p=.004; mean T-scores are 43.5±9.5 and 33.6±12.6 for LOS and EOS, respectively. Additionally, we compared VF performance in each clinical group with age-comparable controls and revealed significantly lower performance in both LOS (U=37.5, p=.001) and EOS (U=56.5, p=.000).

Performance on VF is deteriorated in clinical groups, but may be more intact in LOS compared to EOS. This result is of particular interest because low performance on VF is considered as a cognitive endophenotype of schizophrenia. Performance on VF requires preserved executive functions, language, and processing speed. Our results are in line with the idea that LOS and EOS may be different subtypes of schizophrenia. Limitation of this study is that the clinical groups are not sex-matched.