Trajectories of Hearing From Childhood to Adulthood.

OBJECTIVES: The Dunedin Multidisciplinary Health and Development Study provides a unique opportunity to document the progression of ear health and hearing ability within the same cohort of individuals from birth. This investigation draws on hearing data from 5 to 13 years and again at 45 years of age, to explore the associations between childhood hearing variables and hearing and listening ability at age 45. DESIGN: Multiple linear regression analyses were used to assess associations between childhood hearing (otological status and mid-frequency pure-tone average) and (a) age 45 peripheral hearing ability (mid-frequency pure-tone average and high-frequency pure-tone average), and (b) age 45 listening ability (listening in spatialized noise and subjective questionnaire on listening experiences). Sex, childhood socioeconomic status, and adult IQ were included in the model as covariates. RESULTS: Peripheral hearing and listening abilities at age 45 were consistently associated with childhood hearing acuity at mid-frequencies. Otological status was a moderate predicting factor for high-frequency hearing and utilization of spatial listening cues in adulthood. CONCLUSIONS: We aim to use these findings to develop a foundational model of hearing trajectories. This will form the basis for identifying precursors, to be investigated in a subsequent series of analyses, that may protect against or exacerbate hearing-associated cognitive decline in the Dunedin Study cohort as they progress from mid-life to older age.

Functional topography of the neocortex predicts covariation in complex cognitive and basic motor abilities.

Although higher-order cognitive and lower-order sensorimotor abilities are generally regarded as distinct and studied separately, there is evidence that they not only covary but also that this covariation increases across the lifespan. This pattern has been leveraged in clinical settings where a simple assessment of sensory or motor ability (e.g. hearing, gait speed) can forecast age-related cognitive decline and risk for dementia. However, the brain mechanisms underlying cognitive, sensory, and motor covariation are largely unknown. Here, we examined whether such covariation in midlife reflects variability in common versus distinct neocortical networks using individualized maps of functional topography derived from BOLD fMRI data collected in 769 45-year-old members of a population-representative cohort. Analyses revealed that variability in basic motor but not hearing ability reflected individual differences in the functional topography of neocortical networks typically supporting cognitive ability. These patterns suggest that covariation in motor and cognitive abilities in midlife reflects convergence of function in higher-order neocortical networks and that gait speed may not be simply a measure of physical function but rather an integrative index of nervous system health.

Childhood Social Isolation as a Predictor of Retinal Neuronal Thickness in Middle Age: A Lifecourse Birth Cohort Study.

OBJECTIVE: We investigated whether childhood social isolation was associated with retinal neural layer changes in adulthood, and whether this association was independent of other childhood or adulthood risk factors, including adult social isolation. METHODS: Participants were members of the Dunedin Multidisciplinary Health and Development Study, a longitudinal population-based birth cohort from Aotearoa New Zealand ( n = 1037), born 1972 to 1973 and followed until age 45 years, with 94% of the living cohort still participating. Social isolation was recorded prospectively at ages 5, 7, 9, and 11 years, from teacher and parent report. Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer thicknesses were measured via optical coherence tomography at age 45 years. RESULTS: Childhood social isolation was associated with thinner average RNFL ( B = -0.739, p = .02), nasal RNFL ( B = -1.118, p = .005), and inferior RNFL ( B = -1.524, p = .007), although only nasal RNFL remained significant after adjustment. These associations were not fully explained by other psychosocial or physical health risk factors in childhood or adulthood, nor were they mediated by adult loneliness or social support. CONCLUSIONS: Childhood social isolation was an independent predictor of RNFL thickness in middle age. Highlighting prospective links between childhood psychosocial adversity and retinal neuronal measures will help to inform future research into the utility of retinal neuronal thickness as a biomarker for neurodegeneration.

Functional Topography of the Neocortex Predicts Covariation in Complex Cognitive and Basic Motor Abilities.

Although higher-order cognitive and lower-order sensorimotor abilities are generally regarded as distinct and studied separately, there is evidence that they not only covary but also that this covariation increases across the lifespan. This pattern has been leveraged in clinical settings where a simple assessment of sensory or motor ability (e.g., hearing, gait speed) can forecast age-related cognitive decline and risk for dementia. However, the brain mechanisms underlying cognitive, sensory, and motor covariation are largely unknown. Here, we examined whether such covariation in midlife reflects variability in common versus distinct neocortical networks using individualized maps of functional topography derived from BOLD fMRI data collected in 769 45-year old members of a population-representative cohort. Analyses revealed that variability in basic motor but not hearing ability reflected individual differences in the functional topography of neocortical networks typically supporting cognitive ability. These patterns suggest that covariation in motor and cognitive abilities in midlife reflects convergence of function in higher-order neocortical networks and that gait speed may not be simply a measure of physical function but rather an integrative index of nervous system health.

Are macular drusen in midlife a marker of accelerated biological ageing?

CLINICAL RELEVANCE: Macular drusen are associated with age-related maculopathy but are not an ocular manifestation or biomarker of systemic ageing. BACKGROUND: Macular drusen are the first sign of age-related maculopathy, an eye disease for which age is the strongest risk factor. The aim of this cohort study was to investigate whether macular drusen in midlife - a sign of the earliest stages of age-related macular degeneration (AMD) - are associated with accelerated biological ageing more generally. METHODS: Members of the long-running Dunedin Multidisciplinary Health and Development Study (hereafter the Dunedin Study, n = 1037) underwent retinal photography at their most recent assessment at the age of 45 years. Images were graded for the presence of AMD using a simplified scale from the Age-Related Eye Disease Study (AREDS). Accelerated ageing was assessed by (i) a measure of Pace of Ageing defined from a combination of clinical and serum biomarkers obtained at ages 26, 32, 38, and 45 years and (ii) Facial Ageing, defined from photographs obtained at age 38 and 45 years. RESULTS: Of the 938 participants who participated at the age 45 assessments, 834 had gradable retinal photographs, and of these 165 (19.8%) had macular drusen. There was no significant difference in Pace of Ageing (p = .743) or Facial Ageing (p = .945) among participants with and without macular drusen. CONCLUSIONS: In this representative general population sample, macular drusen in midlife were not associated with accelerated ageing. Future studies tracking longitudinal changes in drusen number and severity at older ages may reveal whether drusen are a biomarker of accelerated ageing.

Childhood sexual abuse and pervasive problems across multiple life domains: Findings from a five-decade study.

The aim of this study was to use longitudinal population-based data to examine the associations between childhood sexual abuse (CSA) and risk for adverse outcomes in multiple life domains across adulthood. In 937 individuals followed from birth to age 45y, we assessed associations between CSA (retrospectively reported at age 26y) and the experience of 22 adverse outcomes in seven domains (physical, mental, sexual, interpersonal, economic, antisocial, multi-domain) from young adulthood to midlife (26 to 45y). Analyses controlled for sex, socioeconomic status, prospectively reported child harm and household dysfunction adverse childhood experiences, and adult sexual assault, and considered different definitions of CSA. After adjusting for confounders, CSA survivors were more likely than their peers to experience internalizing, externalizing, and thought disorders, suicide attempts, health risk behaviors, systemic inflammation, poor oral health, sexually transmitted diseases, high-conflict relationships, benefit use, financial difficulties, antisocial behavior, and cumulative problems across multiple domains in adulthood. In sum, CSA was associated with multiple persistent problems across adulthood, even after adjusting for confounding life stressors, and the risk for particular problems incremented with CSA severity. The higher risk for most specific problems was small to moderate, but the cumulative long-term effects across multiple domains reflect considerable individual and societal burden.

The prevalence of glaucoma among 45-year-old New Zealanders.

AIM: We aimed to estimate the prevalence of glaucoma in New Zealand using a population-based birth cohort of 45-year-olds. METHODS: Study members of the Dunedin Multidisciplinary Health & Development Study participated (n=938 out of 1037 births (91%)). The data collected included visual acuity, visual field (VF), refraction, central corneal thickness, intraocular pressure (IOP), axial length, spectral domain optical coherence tomography (OCT), and non-mydriatic fundus photographs. Two ophthalmologists reviewed data independently to generate a consensus glaucoma status: "Normal" if no suspicion of glaucoma; "Ocular hypertension" if IOP >21 mmHg; "Glaucoma suspect" if optic disc photograph was suspicious for glaucoma with no more than borderline or non-corresponding VF or OCT abnormalities; and "Glaucoma" if optic disc photograph was suspicious for glaucoma and there were corresponding abnormalities of the OCT or VF. RESULTS: Of 891 participants with sufficient data to assign a glaucoma status, 804 were "Normal" (90.2% [CI 88.3-92.2]), 15 were "Ocular hypertension" (1.68% [95% confidence interval (CI) 0.84-2.5]), 65 were "Glaucoma suspect" (7.30% [95% CI 5.6-9.0]), and 7 were classified as "Glaucoma" (0.79% [95% CI 0.21-1.4]). An additional 73 participants (8.2%, [95% CI 6.3%-10%]) had abnormalities on the OCT scan but were not deemed to be glaucoma suspects. CONCLUSION: The prevalence of glaucoma in New Zealand is between 0.2% and 1.4%, consistent with other population-based studies in the same age group. The study highlights the sensitivity of OCT and the potential for misinterpretation and over-investigation.

Associations Between Retinal Nerve Fiber Layer and Ganglion Cell Layer in Middle Age and Cognition From Childhood to Adulthood.

IMPORTANCE: The retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) have been proposed as potential biomarkers for Alzheimer disease (AD). Although a number of studies have shown that knowing the thickness of RNFL and GCL can help differentiate between patients with AD and healthy controls, it is unclear whether these associations are observable earlier in life. OBJECTIVE: To examine whether RNFL and GCL thickness was associated with global cognitive performance in middle age and in childhood and with a decline in cognitive performance from childhood to adulthood and whether RNFL and GCL thickness was associated with decline in specific cognitive domains over the same period. DESIGN, SETTING, AND PARTICIPANTS: This longitudinal cohort study involved members of the Dunedin Multidisciplinary Health and Development Study, a longitudinal representative birth cohort from New Zealand (n = 1037). Participants were born in 1972 to 1973 and followed up until age 45 years, with 94% of the living cohort still participating. MAIN OUTCOMES AND MEASURES: Cognitive performance (Full Scale IQ, processing speed, perceptual reasoning, and verbal comprehension) measured at ages 7, 9, and 11 years (mean value) and age 45 years, and RNFL and GCL thickness measured via optical coherence tomography (OCT) at age 45 years. RESULTS: Data were analyzed between August 2020 and April 2021. Data from 865 participants were included in the present study (50.2% male, 49.8% female; 92.2% of the 938 study members seen at age 45 years). Of the 73 participants who were excluded, 63 were excluded because of issues with OCT scans and 10 were excluded because of diseases affecting the retina. Thinner RNFL and GCL were associated with lower Full Scale IQ in childhood and at age 45 years. Thinner RNFL was also associated with a greater decline in processing speed from childhood to adulthood. CONCLUSIONS AND RELEVANCE: RNFL and GCL thickness in middle age was associated with cognitive performance in childhood and adulthood, and thinner RNFL with a decline in processing speed between childhood and adulthood. These data emphasize the potential utility of OCT measures as biomarkers of cognitive function; however, further longitudinal studies are needed to determine whether retinal thinning precedes cognitive decline and whether other confounding factors may account for this association.

Hippocampal Sequencing Mechanisms Are Disrupted in a Maternal Immune Activation Model of Schizophrenia Risk.

Episodic memory requires information to be stored and recalled in sequential order, and these processes are disrupted in schizophrenia. Hippocampal phase precession and theta sequences are thought to provide a biological mechanism for sequential ordering of experience at timescales suitable for plasticity. These phenomena have not previously been examined in any models of schizophrenia risk. Here, we examine these phenomena in a maternal immune activation (MIA) rodent model. We show that while individual pyramidal cells in the CA1 region continue to precess normally in MIA animals, the starting phase of precession as an animal enters a new place field is considerably more variable in MIA animals than in controls. A critical consequence of this change is a disorganization of the ordered representation of experience via theta sequences. These results provide the first evidence of a biological-level mechanism that, if it occurs in schizophrenia, may explain aspects of disorganized sequential processing that contribute to the cognitive symptoms of the disorder.SIGNIFICANCE STATEMENT Hippocampal phase precession and theta sequences have been proposed as biophysical mechanisms by which the sequential structure of cognition might be ordered. Disturbances of sequential processing have frequently been observed in schizophrenia. Here, we show for the first time that phase precession and theta sequences are disrupted in a maternal immune activation (MIA) model of schizophrenia risk. This is a result of greater variability in the starting phase of precession, indicating that the mechanisms that coordinate precession at the assembly level are disrupted. We propose that this disturbance in phase precession underlies some of the disorganized cognitive symptoms that occur in schizophrenia. These findings could have important preclinical significance for the identification and treatment of schizophrenia risk factors.

Characterising the ocular surface and tear film in a population-based birth cohort of 45-year old New Zealand men and women.

PURPOSE: To assess the prevalence of dry eye disease, aqueous tear deficiency, meibomian gland dysfunction, and asymptomatic ocular surface disease in a population-based cohort of 45-year-old New Zealand men and women. METHODS: This cross-sectional study of 885 participants (442 females, 443 males) was based on a population-representative birth cohort of individuals born between April 1 1972 and March 31 1973 in Dunedin, New Zealand (the Dunedin Multidisciplinary Health and Developmental Study). Participants were assessed at 45 years of age, and dry eye symptomology, ocular surface characteristics, and tear film quality were evaluated for each participant within a single clinical session. The diagnosis of dry eye disease was made according to the validated rapid non-invasive dry eye assessment algorithm. RESULTS: Clinical dry eye signs were present in 402 (45%) participants, of which 78 (9%) participants fulfilled the diagnostic criteria for dry eye disease, and 322 (37%) had asymptomatic ocular surface disease. Among participants with dry eye disease, 22 (2%) exhibited aqueous tear deficiency, and 65 (7%) had meibomian gland dysfunction. Females were more likely to be affected by dry eye disease, meibomian gland dysfunction, and asymptomatic ocular surface disease (all p < 0.05). CONCLUSIONS: Clinical dry eye signs were present in almost half of this population-based cohort of 45-year-old New Zealanders, although only 9% of participants fulfilled the diagnostic criteria for dry eye disease. The high prevalence of asymptomatic ocular surface disease presents an opportunity for preventative public health intervention.

On the use of a new monocular-indirect ophthalmoscope for retinal photography in a primary care setting.

AIM: There is consensus among general practitioners regarding the difficulty of direct ophthalmoscopy. Hence, there is increasing interest in smartphone-based ophthalmoscopes; the New Zealand-made oDocs Nun ophthalmoscope is one such device, released in November 2018. This study aims to subjectively assess the quality of the images captured with it in order to determine the feasibility of its use in a primary care setting. METHOD: Twenty-eight general practitioners (GPs) from different practices throughout New Zealand agreed to participate in this prospective observational study and were sent an oDocs Nun ophthalmoscope. Using the device, clinicians took retinal photographs of patients who presented with visual complaints and uploaded one image per eye onto a database. Three hundred and fifty-seven photographs were collated and rated by four professionals (two ophthalmologists and two optometrists) on the basis of image quality and the anatomical features visible. RESULTS: On a Likert scale from 1 (poor quality) to 4 (very good quality), the median and mode values for each professional's rating of all photographs were both 2. On average, 94.5% of the photographs were deemed to have visible optic discs and 50.0% to have visible maculae adequate for detecting an abnormality. Pairwise comparison showed 93.7% agreement among the four professionals for optic disc visibility, and 74.2% agreement for macula visibility. CONCLUSION: The oDocs Nun is a promising tool which GPs could use to circumvent the challenges associated with direct ophthalmoscopy. With appropriate training to ensure proficiency, it may have a valuable role in telemedicine and tele-referral.

The Detection of Spontaneous Venous Pulsation with Smartphone Video Ophthalmoscopy.

PURPOSE: Spontaneous venous pulsation (SVP) has a high negative predictive value for raised intracranial pressure and is a useful sign when assessing patients with headache. The objective was to determine if smartphone-based video ophthalmoscopy can detect SVP. PATIENTS AND METHODS: In total 233 patients and 291 eyes were recruited from the Dunedin Hospital eye clinic from July to November 2018. Patients were examined by a clinician and graded for SVP with a slit lamp and 78 Dioptre lens. Videos were taken with a smartphone ophthalmoscope and graded by two separate clinicians blinded to the slit lamp findings. RESULTS: Only 272 eyes of 215 patients were included, as others failed in the inclusion criteria for overall video quality. Sensitivity was calculated as how likely the presence of SVP on video was indicative of the presence of SVP on slit lamp. Sensitivity was 84.77% for Observer 1, with 128 videos graded as positive for SVP on video ophthalmoscopy of the 151 identified as positive on slit lamp examination. Sensitivity was 76.82% for Observer 2 with 116 videos correctly identified. The false positive rate was calculated as the number of videos graded positive for SVP that had been graded as negative on slit lamp examination. This was 10.74% for observer 1 and 31.40% for observer 2. CONCLUSION: This study demonstrates that SVP is detected by video ophthalmoscopy. This may be a useful triage, telemedicine and referral tool to be used for patients with headache in a primary care setting.

Exposure to complex environments results in more sparse representations of space in the hippocampus.

The neural circuitry mediating sensory and motor representations is adaptively tuned by an animal's interaction with its environment. Similarly, higher order representations such as spatial memories can be modified by exposure to a complex environment (CE), but in this case the changes in brain circuitry that mediate the effect are less well understood. Here, we show that prolonged CE exposure was associated with increased selectivity of CA1 "place cells" to a particular recording arena compared to a social control (SC) group. Furthermore, fewer CA1 and DG neurons in the CE group expressed high levels of Arc protein, a marker of recent activation, following brief exposure to a completely novel environment. The reduced Arc expression was not attributable to overall changes in cell density or number. These data indicate that one effect of CE exposure is to modify high-level spatial representations in the brain by increasing the sparsity of population coding within networks of neurons. Greater sparsity could result in a more efficient and compact coding system that might alter behavioural performance on spatial tasks. The results from a behavioural experiment were consistent with this hypothesis, as CE-treated animals habituated more rapidly to a novel environment despite showing equivalent initial responding.

Behavioural deficits associated with maternal immune activation in the rat model of schizophrenia.

Schizophrenia is associated with changes in memory and contextual processing. As maternal infection is a risk factor in schizophrenia we tested for these impairments in a maternal immune activation (MIA) animal model. MIA rats displayed impaired object recognition memory, despite intact object discrimination, and a reduced reinstatement of rearing in response to a contextual manipulation. These results link MIA to contextual impairments in schizophrenia, possibly through changes in hippocampal function.