Discussion

To the best of our knowledge, this analysis is the largest and most recent assessment of time trends for general anxiety in general practice. This is likely because of the general lack of large, standardised primary care data-sets. The most important finding of this analysis is the sharp increase in the recording of generalised anxiety disorders and symptoms in the past few years, and the disproportionate impact of this increase on young adults. Recording rates for the combination of generalised anxiety, depression or mixed have been relatively stable, except for sharp increases for men and women aged 18–24 in the past 10 years, and a moderate increase for men aged 25–34 years in the past 4 years. Although the rates of incident recordings for generalised anxiety are about twice as high for men compared with women across age cohorts, the rates of the recent increases in the youngest cohorts are parallel across genders, suggesting that the increases in rates over time are similar. For women aged 35–44 years and 45–54 years, the recent increase in generalised anxiety corresponds with a decrease in the composite of generalised anxiety, depression or mixed. Taken together, these findings could illustrate a difference in general practitioner recording patterns. However, for the cohorts of women aged ≥55 years, there has been no increase in generalised anxiety and, simultaneously, a decrease in the composite, suggesting temporal changes in depression for older women. For men aged 18–24 years and 25–34 years, both generalised anxiety and the composite were increased, which is inconsistent with a change in reporting patterns. The trends since about 2008 are largely similar for anxiety diagnoses and anxiety symptoms, although from 1998 to 2008 there were declines in diagnoses and slight increases in anxiety symptom recording across all strata. This could be explained by change in coding practice by the general practitioners over this period, which seemed to stabilise thereafter.

Consistent with previous reports,^{Reference Bandelow and Michaelis22–Reference Remes, Wainwright, Surtees, Lafortune, Khaw and Brayne24} this analysis demonstrates generalised anxiety is much more commonly reported in women than men. To the best of our knowledge, the recent substantial increase in generalised anxiety in younger cohorts has not been previously reported in a UK general practice setting, which is of considerable public health importance. This increase may reflect an underlying increase in generalised anxiety in the general population or an increasing awareness of, and investigation for, generalised anxiety on the part of general practitioner, although the concentration of the increase in the younger adults may mitigate against a change in general practitioner behaviour being a plausible explanation for these observations. Although the increase is most striking in young women, there has also been a significant recent increase in generalised anxiety recording for young men. The median healthcare cost for persons with generalised anxiety disorder are estimated to be 64% higher than for those without generalised anxiety disorder,^{Reference Olfson and Gameroff25} so, along with considerable health decrement, this recent increase in recording is likely to cause a material depletion of budgeted resources. Although the increases were similar across genders, the budget and public health impact of the increase for women will be greater than for men, because of the initial rate differences. Primary care clinicians may usefully be aware of these increases and remain vigilant for generalised anxiety disorders and symptoms in all young adults.

Changes in suicide rate in the UK are consistent with the changes in generalised anxiety and depression. Correlates of suicide that may also interact with mental illness include psychosocial crisis, hopelessness, impulsivity, treatment and many others. Although young people represent a small number of total suicide deaths, the suicide rates among 10- to 24-year-olds have increased recently for both genders, according to the 2018 report from the Office for National Statistics. There was a significant increase of 31% from 2017 to 2018 among males aged 20–24 years. Among females aged 10–24 years, the suicide rate in 2018 was 3.3 deaths/100 000 females, which is the highest rate since recording began in 1981. Comparing the changes from 2014 to 2018, there have been increases in the two youngest age cohorts, with the increase in the 10–24 years cohort about twice the increase in the 25–44 years cohort.²⁶ Although suicide is more common in men than women across all age groups, self-harm is more common in women. A recent study of adolescents in the UK found a 68% increase in self-harm among girls aged 13–16 years, from 45.9 per 10 000 in 2011 to 77.0 per 10 000 in 2014.^{Reference Morgan, Webb, Carr, Kontopantelis, Green and Chew-Graham27} A study based on data from the National Self-Harm Registry in Ireland found increases between 2007 and 2016 in self-harm presenting at hospital emergency rooms of 14% and 29% for males and females aged 10–24 years, respectively.^{Reference Griffin, McMahon, McNicholas, Corcoran, Perry and Arensman28} Whether and how increases in generalised anxiety and depression relate to increases in self-harm and suicide is unclear, but it is clear that increases in both psychiatric and behavioural changes are affecting young people, and young women in particular.

It is notable that rates of generalised anxiety disorders and symptoms began their current upward trajectory around the time that the effects of the 2008 economic downturn and during the policy of austerity. The relationship between employment,^{Reference Ford, Campion, Chamles, Habash-Bailey and Cooper29,Reference Moore, Kapur, Hawton, Richards, Metcalfe and Gunnell30} finances^{Reference Sweet, Kuzawa and McDade31,Reference Drentea and Reynolds32} and anxiety is well known. Of note, generalised anxiety is also taking a toll on employed people; the Office for National Statistics reported a 24% increase between 2009 and 2014 in the number of sick days lost to ‘stress, depression and anxiety’ in England and Wales.³³

The difference in generalised anxiety rates by age probably reflect several recent changes. Social media use, which early research suggests is strongly associated with anxiety, is more common among young people and may be partly responsible. A recent study in 563 emerging adults (aged 18–22 years) found that daily social media use was associated with dispositional anxiety scores indicating a probable anxiety disorder.^{Reference Vannucci, Flannery and Ohannessian34} Profitable social media platforms use a business model that monetises the attention of users by selling it to advertisers, but in actuality, social media users are the product and not the customers. Maximising profit is analogous to maximising the amount of time that users spend engaged with the platform, which can interfere with personal and professional responsibilities. For example, in the USA, a study of 1730 adults aged 19–32 years identified five categories of social media use. The two highest levels (labelled ‘wired’ and ‘connected’) had odds ratios of 1.9 and 3.1 for depression and 4.5 and 2.2 for anxiety symptoms compared with the lowest level (‘unplugged’).^{Reference Shensa, Sidani, Dew, Escobar-Viera and Primack35} However, it is unclear to what extent these relationships may be causal or, alternatively, an alternate manifestation of the underlying anxiety. In addition, cuts to social services may disproportionately affect young people, as housing, university or apprenticeship opportunities, and employment are less certain under the recent austerity paradigm. These uncertainties may disproportionately increase generalised anxiety in young people who are seeking to establish careers, and have minimal effect on people with well-established careers and retired people.

Previous research has described the link between anxiety and drug use.^{Reference Grant, Stinson, Dawson, Chou, Dufour and Compton36} Increasing anxiety rates are temporally associated with changes in drug and alcohol use in young adults in the UK. However, the increases in anxiety in this analysis are occurring against a backdrop of recent reductions in alcohol use among young adults. A longitudinal assessment of 10 000 people aged 16–24 years showed an increase in the proportion of non-drinkers and a reduction in the rate of binge drinking from 2005 to 2015.^{Reference Ng Fat, Shelton and Cable37}The Office for National Statistics Opinions and Lifestyle Survey also found recent reductions in alcohol consumption, and especially among 16- to 24-year-olds.³⁸ The trends are more ominous for illicit drug use. An international 7-year analysis of wastewater demonstrated higher levels of cocaine (based on benzoylecgonine levels) and 3,4-methylenedioxy-methamphetamine (MDMA, ecstasy) consumption in the UK in 2014–2017 compared with 2011–2013.^{Reference González-Mariño, Baz-Lomba, Alygizakis, Andrés-Costa, Bade and Bannwarth39} The Office for National Statistics reports that illicit drug use in the UK for adults aged 16–59 years has remained relatively stable over the past decade, although there has been a slight increase recently.⁴⁰ Young adults aged 16–24 years appear to be responsible for this increase, and higher incidences of powder cocaine and ecstasy use were reported in this age group. Drug use is lower for women compared with men, but the difference in rates of use is largely unchanged since 2008.

Although we continue to study the underlying reasons for increasing rates of generalised anxiety, there are several effective therapeutic^{Reference Slee, Nazareth, Bondaronek, Liu, Cheng and Freemantle41} and psychological^{Reference Bandelow, Sagebiel, Belz, Gorlich, Michaelis and Wedekind42} treatments for generalised anxiety disorder, although how these treatment options perform on a group of patients identified by symptoms rather than generalised anxiety disorder diagnoses has not been studied. One of the key messages in the 2011 NICE generalised anxiety guidelines was the recommendation not to prescribe benzodiazepine as a treatment for generalised anxiety disorder, and to limit its duration of use to 1–2 weeks. We did not examine duration in this study, but we did identify a reduction in benzodiazepine prescribing among psychotropic-naïve (at least in the past year) patients. Sertraline, an SSRI, is the recommended first-line therapy, and the proportion of patients diagnosed with generalised anxiety who received an SSRI prescription increased, to become the most common therapeutic category over the course of the study. The increase in SSRI use and reduction in benzodiazepine use began before the publication of the NICE guidelines,⁵ but since the release of the guidelines, both trends have continued. When patients taking medication before recorded generalised anxiety were considered, these patterns were largely similar. The use of TCAs was more common at the beginning of this study, but there has been a steady reduction over time. These findings suggest that general practitioners are aware of the NICE guidelines, and prescribing patterns are more adherent to these recommendations now than at any prior time point.

This analysis has several limitations. First and foremost, it is based on identification of symptoms and diagnoses in patients seeking help from their general practitioners. We selected data by using the practice specific quality indicators of acceptable computer usage^{Reference Horsfall, Walters and Petersen14} and mortality reporting,^{Reference Maguire, Blak and Thompson13} which should improve the accuracy of the data in our analysis, but may slightly reduce generalisability. Although there is evidence for the accuracy of recorded diagnoses among those who seek help,^{Reference Khan, Harrison and Rose43} these results will underestimate the incidence rates of generalised anxiety and depression in the UK because many patients experiencing generalised anxiety and depression do not seek help, or do not seek help from their primary care general practitioner. However, this analysis does represent a broad group of patients who do present to their general practitioners seeking help. As described above, there is some evidence of hesitation on the part of general practitioners to record generalised anxiety disorders even when suspected clinically, and to instead report generalised anxiety symptoms. The reluctance to record mental illness may extend further, to a group presenting with generalised anxiety symptoms where even these are not recorded. In addition, we cannot determine whether changes in reporting of generalised anxiety and depression are driven by changes in the relative rates of underlying disease, in health-seeking behaviour or simply a change in the way general practitioners classify patients with an overlapping set of symptoms. However, especially in young people, the evidence of a recent increase in rates is impervious to these classification problems.

An additional limitation is that our analysis was restricted to generalised anxiety and did not examine other anxiety disorders such as panic disorder, obsessive–compulsive disorder and social phobias. Although generalised anxiety is frequently comorbid with other anxiety disorders, the context and management of generalised anxiety differ from other anxiety disorders, and this work is insufficient to address these nuances adequately. Our analysis also did not account for concurrent substance misuse, which is also comorbid with anxiety disorders but tends to be poorly coded in general practice.^{Reference Davies, Nazareth and Petersen44}