Traumatic life experiences and post‐traumatic stress symptoms in middle‐aged and older adults with and without autistic traits

Research with younger adults has begun to explore associations between autism/autistic traits and vulnerability to Post Traumatic Stress Disorder (PTSD). Large scale studies and/or examination of age‐effects have not been conducted.


| INTRODUCTION
Autism is a neurodevelopmental condition characterised by differences in social communication and restricted-repetitive behaviours. 1 Autism is increasingly seen as lying at one end of a spectrum, with common genetic influences operating on diagnosed autism and subclinical autistic traits in the general population. 2,3 Autism affects approximately 1% of the general population, with an additional 10%-20% endorsing high but sub-clinical autistic traits. 4 Despite autism being a lifelong condition and an ageing demographic in many countries, most autism research has examined children and young adults with little attention on old age. 5 Research suggests that autistic adults experience higher rates of trauma and post-traumatic stress disorder (PTSD) compared to the general population. 6 The rates of trauma and PTSD in autistic adults in latter life has not yet been explored, despite evidence that effects of trauma persist across the lifespan and into old-age. 7 By examining the association of autistic traits with trauma, it is possible to explore the influence of autism in understudied (and possibly under-diagnosed) populations, such as in older age. 8,9 It has been posited that core features of the symptomology and genetic aetiology of autism may increase the risk of trauma exposure. 6,10 Studies exploring traumatic experiences have typically focused on early life, with elevated rates of emotional and physical abuse and neglect being reported by autistic children and retrospectively by autistic adults. [10][11][12][13][14][15] Elevated rates of childhood sexual abuse have also been reported, in particular by autistic women and girls. 12,15 This increased vulnerability to traumatic experiences has also been documented in adulthood, with autistic and high autistic trait adults reporting higher rates of emotional and domestic abuse, sexual and physical violence, and victimisation 13,16,17 compared to the general population. The impact that these experiences may have in old age has not yet been explored.
In the general population, the experience of trauma has been identified as a risk factor for subsequent psychiatric difficulties, including the development of PTSD, depression, and anxiety. 17 Posttraumatic stress disorder symptoms include recurrent, involuntary, and intrusive distressing memories following the experience of a traumatic event, 1 and are associated with a wide range of negative physical, psychological, and adaptive outcomes over the life course. 7,18 Clinical PTSD affects approximately 4%−7% of the general population 19,20 ; however, in adults aged 55 and over this prevalence has been found to be lower, with rates of approximately 1%-2%. 21,22 The prevalence of clinical PTSD among autistic adult populations has not been widely studied, but estimates suggest prevalence rates up to 17% in childhood 6,23 and 16% in adulthood, 13 while rates among older autistic adults are unknown. Elevated rates of depression (OR = 2.8−5.6) and anxiety (OR = 3.3−6.2) have also been documented in autistic populations across the lifespan, 24,25 and recently in older adults with high autistic traits. 26 A small selection of studies has examined the prevalence of traumatic experiences and PTSD symptoms in younger autistic populations, however, there has yet to be any examination of either autistic or high autistic traits populations in mid-life or older age.
Studies examining older adults in the general population have reported that the impact of trauma and subsequent PTSD symptoms often persist throughout the life course. 7,27 Trauma experienced during different developmental periods may lead to different PTSD symptom severities and outcomes. 7 Childhood is a period of rapid cognitive and psychosocial development, making it a vulnerable period for the effects of trauma. Older adults who experience abuse and neglect during childhood often experience more severe PTSD symptoms than those who experience trauma in other developmental periods. [28][29][30][31] Furthermore, older adults who report severe trauma in childhood have been found to experience lower subjective happiness and to be less able to cope with stress than those who experience trauma at latter ages. 28 Additionally, severe childhood trauma has been found to lead to a 12-fold increase in the likelihood of mental health crises in adulthood and older age, including higher rates of suicidal ideation and behaviours. [29][30][31][32] Therefore, while experiencing trauma at any age can lead to subsequent PTSD symptoms, older adults with high autistic traits who have experienced trauma during childhood may be vulnerable to more severe PTSD symptoms in latter life.
The current study investigates the prevalence of traumatic experiences in childhood and adulthood and current symptoms of PTSD, depression, and anxiety in a large sample of adults aged 50 years and older. It is hypothesised that older adults with high autistic traits (AST) will (1) report a higher prevalence of traumatic childhood and adulthood experiences, (2) report elevated and above clinical cut-off symptoms of PTSD, depression, and anxiety, and that (3) exposure to severe trauma in childhood/adulthood will be associated with elevated symptoms of PTSD, depression, and anxiety, when compared to a matched group who do not endorse any autistic traits Comparison Older Adults (COA).  relating to having been bothered by a range of problems over the past two weeks. On the original 20-item PCL participants who on average across items report "2 = moderate" or above are considered to meet criteria for probable clinical PTSD symptoms. Using this criterion, those with scores ≥10 were identified as likely to be experiencing probable clinical PTSD symptoms.

Recent depression was measured using the Patient Health
Questionnaire (PHQ-9 36 ). The PHQ-9 is a nine-item questionnaire (rated on a 4-point scale, maximum score = 27) examining low mood over the past two weeks. Using the conventional cut-off score of ≥10, the PHQ-9 has 88% sensitivity and 88% specificity for major depressive disorder.
Recent anxiety was measured using the General Anxiety Disorder questionnaire (GAD-7 37 ). The GAD-7 is a seven-item questionnaire (rated on a 4-point scale, maximum score = 21) examining anxiety symptoms over the past two weeks. Using the conventional cut-off score of ≥10, the GAD-7 has 89% sensitivity and 82% specificity for generalised anxiety disorder.

| Statistical analyses
All statistical analyses were performed using SPSS (version 25.0; IBM Corp., 2017). Multiple comparisons were controlled for using the False Discovery Rate method, 38 with an α of 0.05 being used.

| Specific types of traumatic events in childhood and adulthood
For trauma in childhood, the AST group reported significantly higher rates on all items compared to COA, including emotional, physical, and sexual abuse. For trauma in adulthood, the AST group reported significantly higher rates on items concerning emotional, physical, and sexual abuse, but not financial hardship (see Table 2).

| Gender differences
Some gender differences were observed in the types of trauma experienced. In childhood, more COA females than males reported experiencing emotional and sexual abuse. In adulthood, both COA and AST females reported experiencing more physical, emotional and sexual abuse than COA and AST males. Additionally, more COA females reported experiencing financial hardship than COA males (see Supplementary Table S1).

| Self-reported trauma and psychiatric difficulties
The AST group reported significantly higher trauma scores in childhood and adulthood than individuals in the COA group.
Additionally, the AST group reported significantly more current symptoms of PTSD, depression, and anxiety than the COA group (see Table 3). rates of symptoms when compared to COA males, but no differences were found between AST males and females (see Supplementary Table S2).

| Experiences of above cut-off trauma and psychiatric difficulties
More individuals in the AST versus COA group met cut-off criteria for childhood trauma, adulthood trauma, and current symptoms of PTSD, depression, and anxiety (see Table 3). Twenty-two (8.8%) of the AST group and 213 (2.3%) of the COA group met cut-off criteria for both childhood and adulthood trauma (see Supplementary Figure   S1 Venn diagram showing overlap).

| Gender differences
More COA females than males met cut-off criteria for childhood and adulthood trauma, current symptoms of PTSD, and depression. No gender difference were observed for anxiety. More AST females than males met cut-off criteria for adulthood trauma, with no other gender differences observed (see Supplementary Table S3 for details). Note: N (%) endorsing "sometimes" or more frequently. "R" items are reverse coded, with square bracketed words for context. *p < 0.05, **p < 0.01, ***p < 0.001.

| Association of severe trauma with psychiatric difficulties
Using the 95th percentile cut-offs described above, participants were categorised into childhood and adulthood "High Trauma" or "Low Trauma" groups.  Table 4).  Table 5.

| Associations between trauma and PTSD symptoms
For the AST group, significant moderate positive associations were found between PTSD symptoms and childhood trauma (r = 0.42, p < 0.001), and PTSD symptoms and adulthood trauma (r = 0.27, p < 0.001), with the former significantly stronger than the latter association (z = 1.85, p < 0.001).
For the COA group, significant small positive associations were found between PTSD symptoms and childhood trauma (r = 0.15, p < 0.001), and PTSD symptoms and adulthood trauma (r = 0.21, p < 0.001), with the latter being significantly stronger than the former association (z = −4.28, p < 0.001).
Comparing groups, the strength of the PTSD symptoms and childhood trauma association was significantly stronger in AST than T A B L E 3 Self-report questionnaire means, standard deviations and confidence intervals of the Control Older Adult (COA) and Autism Spectrum Traits (AST) groups Note: Childhood Trauma measured using CTS-5; Adulthood Trauma measured using ATS-5; Post-Traumatic Stress measured using PCL-CSF; Depression measured using PHQ-9; Anxiety measured using GAD-7. *p < 0.05, **p < 0.01, ***p < 0.001.

| Post-hoc analyses of the intermediate (INT) group
The pattern of results showed that the INT group fell between the other two groups, generally scoring significantly worse than the COA group and significantly better (e.g., less trauma, lower PTSD symp- High rates of many types of trauma were observed in our older adult sample, consistent with the previous literature exploring the occurrence of childhood and adulthood traumatic experiences in autistic and high autistic trait populations. [10][11][12][13]15,17 Those with high autistic traits reported elevated rates of emotional and physical abuse or neglect, as well as sexual abuse, when compared to the comparison sample; almost 30% of the AST group, compared to less than 8% of the COA, reported severe trauma in childhood/adulthood. These higher rates represented a three-to-eightfold increased incidence of trauma during childhood, and a three-to-fivefold increased incidence of trauma during adulthood. Notably, emotional traumas were also reported at particularly high rates in the AST group compared to COA, including an eight-fold increase in emotional neglect and seven-fold increase in emotional abuse.
These higher rates of emotional trauma were also found in adulthood, with the AST group reporting higher rates than the COA group for emotional neglect and emotional abuse. This finding may be of particular importance; in the general population, emotional neglect and abuse during childhood have been identified as key precursors to poor psychosocial development and subsequent psychiatric difficulties during adulthood, including an increased likelihood for PTSD, depression, and anxiety symptoms. 29  population of older adults, and represent a first step towards greater understanding of ageing for those with persistent poor socio-communicative functioning.
In conclusion, our study exploring the experience of trauma and psychiatric difficulties of older adults suggests that those who selfreport high autistic traits are at greater risk of experiencing trauma across the lifespan, as well as symptoms of PTSD, depression and anxiety in older age. Indeed, self-reported childhood or adulthood trauma appears to be even more damaging to those with high autistic traits than to the general population, in terms of PTSD and depression symptoms in older adulthood. As such, individuals with high autistic traits-and especially those who have experienced severe trauma-may benefit from intervention to mitigate this vulnerability.
The findings of the current study highlight the need for adequate mental health support for those on the autism spectrum, including those with high traits who may not have a diagnosis, to ensure that they receive appropriate support to prevent psychiatric problems and resulting crises, such as suicide.

ACKNOWLEDGEMENT
This paper represents independent research funded by the National