Cortical microvascular raspberries and ageing: an independent but not exclusive relationship.

INTRODUCTION: Raspberries are cerebral microvascular formations of unknown origin, defined as three or more transversally sectioned vascular lumina surrounded by a common perivascular space. We have previously demonstrated an increased raspberry density in the cortex of patients with vascular dementia and cerebral atherosclerosis, while studies by other authors on overlapping and synonymously defined vascular entities mainly associate them with advancing age. The aim of the present study was to examine the relationship between raspberries and age in a large study sample while including multiple potential confounding factors in the analysis. MATERIALS AND METHODS: Our study sample consisted of 263 individuals aged 20-97 years who had undergone a clinical autopsy including a neuropathological examination. The cortical raspberry density had either been quantified as part of a previous study or was examined de novo in a uniform manner on haematoxylin- and eosin-stained tissue sections from the frontal lobe. The medical records and autopsy reports were assessed regarding neurodegeneration, cerebral infarcts, cerebral atherosclerosis and small vessel disease, cardiac hypertrophy, nephrosclerosis, hypertension, and diabetes mellitus. With the patients grouped according to 10-year age interval, non-parametric tests (the Kruskal-Wallis test, followed by pairwise testing with Bonferroni-corrected P values) and multiple linear regression models (not corrected for multiple tests) were performed. RESULTS: The average raspberry density increased with advancing age. The non-parametric tests demonstrated statistically significant differences in raspberry density when comparing the groups aged 60-99 years and 70-99 years to those aged 20-29 years (P < 0.012) and 30-59 years (P < 0.011), respectively. The multiple linear regression models demonstrated positive associations with age interval (P < 0.001), cerebral atherosclerosis (P = 0.024), cardiac hypertrophy (P = 0.021), hypertension subgrouped for organ damage (P = 0.006), and female sex (P = 0.004), and a tendency towards a negative association with Alzheimer's disease neuropathologic change (P = 0.048). CONCLUSION: The raspberry density of the frontal cortex increases with advancing age, but our results also indicate associations with acquired pathologies. Awareness of the biological and pathological context where raspberries occur can guide further research on their origin.

On the regional distribution of cerebral microvascular 'raspberries' and their association with cerebral atherosclerosis and acute circulatory failure.

Introduction: In this follow-up study, cerebral microvascular formations termed 'raspberries' were quantified according to cerebral atherosclerosis (C-ASCL) and acute circulatory failure (ACF). We also examined the regional distribution of raspberries throughout the brain. Materials and methods: The study population consisted of adult individuals who had undergone a diagnostic neuropathological autopsy. Groups were formed to examine the association between raspberries, C-ASCL and ACF (control group, C-ASCL group, C-ASCL+ACF group [n = 47 per group] and a combined C-ASCL-tot group [n = 94]). To examine the regional distribution, additional groups were formed based on previously known raspberry densities of the frontal cortex (high-, medium- and low-density group [n = 6 per group]). Raspberries were quantified on scanned haematoxylin-eosin-stained sections. Results: Cortical raspberry density did not differ at a statistically significant level between the control group, the C-ASCL group and the C-ASCL+ACF group (P = 0.10) but did so between the control group and the C-ASCL-tot group (P = 0.033). The total raspberry density of the high-, medium- and low-density groups differed at a statistically significant level (P = 0.005), which remained in group-to-group comparisons of the high- and medium-density groups (P = 0.015) and the high- and low-density groups (P = 0.002). Raspberries were rare in cerebral white matter and in the cerebellum. Conclusion: An association between raspberry density and C-ASCL is supported but is weaker than previously indicated. An association with ACF is not indicated. The raspberry density of the frontal cortex provides an approximation of the brain's total raspberry density.

Are cortical microvascular raspberries caused by cerebral hypoperfusion? An exploratory pathological study.

Introduction: This retrospective study investigated a cortical microvascular formation, termed a 'raspberry' due to its appearance under a bright-field microscope. We examined whether there is support for the hypothesis that raspberry formation is an angiogenic process induced by cerebral hypoperfusion. Materials and Methods: Raspberries were manually quantified in haematoxylin and eosin-stained cortical sections from the anterior frontal lobe of deceased individuals who had undergone a diagnostic neuropathological examination at the Department of Pathology, Lund, Sweden, during April 2019-January 2021. Subjects represented consecutively received cases during this 22-month period. The raspberry density was compared between subjects according to variables collected from medical records and autopsy reports: age, sex, hypertension, diabetes mellitus, atrial fibrillation, orthostatic hypotension, chronic heart failure, acute circulatory failure, aortic atherosclerosis, atherosclerosis of the basal cerebral arteries (referred to as 'cerebral atherosclerosis'), cerebral small vessel disease, cerebral amyloid angiopathy, cerebral infarction, and ischaemic white matter disease. Results: 62 subjects were included. The mean age was 71.9 years (range 46-97 years). 21 subjects (33.9%) were female. Independent-samples t-test showed a higher raspberry density in subjects with cerebral atherosclerosis (p = 0.029; 95% CI 0.7, 11.6 raspberries/cm²). The higher raspberry density in subjects with cerebral atherosclerosis remained in multiple linear regression (p = 0.003; 95% CI 2.3, 11.1 raspberries/cm²). Conclusion: This exploratory study indicates that cortical raspberries could be associated with cerebral atherosclerosis. The remaining results were inconclusive but motivate further examination of variables such as acute circulatory failure.