Prevalence of psychiatric disorder
This level of prior contact with services is commensurate with the very high prevalence of disorders identified in our sample. As indicated above, our sampling strategy is likely to result in prevalence rates somewhat higher than those using the single-sample approach. In Table
3, we provide comparisons with NPMS-P [
6], and with the English Adult Psychiatric Morbidity Survey of 2007 [
24], together with data from systematic reviews of international studies of mental disorder in prisons [
13,
30,
31]. Overall, the gender differences in our survey were less marked than would be expected from general population rates. In fact, morbidity rates were generally consistent between the sexes, and the differences in this sample were not statistically significant (with the exception of PTSD and phobias). This suggests that the increased permeability of the prison/community boundary to people with mental health problems is greater in men.
Table 3
Comparison of ANPTP results with other relevant findings
Psychosis |
Men | 14.2 | 8.4 | 3.6 | 4 | 4 | 0.3 |
Women | 9.9 | 13.8 | 3.9 | 4 | 4 | 0.5 |
Depressive states* |
Men | 49.2 | 35.5 | | | | 8.8 |
Women | 58.0 | 48.6 | | | | 13.8 |
Depressive episode |
Men | 19.9 | 12.8 | 10.2 | 10 | 10 | 1.9 |
Women | 23.7 | 16.5 | 14.1 | 12 | 12 | 2.8 |
Anxiety states†
|
Men | 29.1 | 22.3 | | | | 5.2 |
Women | 24.3 | 27.9 | | | | 8.5 |
Phobias |
Men | 6.6 | 8.1 | | | | 0.8 |
Women | 16.0 | 12.7 | | | | 2.0 |
Panic |
Men | 5.1 | 4.6 | | | | 1.0 |
Women | 5.9 | 4.2 | | | | 1.2 |
PTSD |
Men | 4.6 | 4.1 | | 4–21 | | 2.6 |
Women | 12.0 | 9.1 | | 10–21 | | 3.3 |
Antisocial personality disorder |
Men | 26.4 | 55.2 | | 65 | 47 | 0.6 |
Women | 17.5 | 31.4 | | 42 | 21 | 0.1 |
Borderline personality disorder |
Men | 10.7 | 18.1 | | | | 0.3 |
Women | 15.2 | 20.0 | | | | 0.6 |
Alcohol dependence |
Men | 32.0 | NA | | 18–30 | | 8.7 |
Women | 34.3 | | | 10–24 | | 3.3 |
Drug dependence |
Men | 54.8 | 47.2 | | 10–48 | | 4.5 |
Women | 59.6 | 54.1 | | 30–60 | | 2.3 |
Both NPMS-P and the current study identified rates of psychiatric disorder much higher than in members of the community at large. This is particularly clear in relation to the more severe disorders: depressive episode and, notably, psychosis. This skew towards severity is apparent in the ratio between the prevalences of mixed anxiety/depression and depressive episode: while this is 3.7 in the general population, it is only 1.4 in our prison sample.
ANPTP and NPMS-P both found a very high prevalence of psychosis. This was over 20 times the 0.5% prevalence in the English population [
32], and appears to have persisted for the 15 years separating the studies. However, in their systemic review, Fazel and Seewald [
13] reported a much lower prevalence of 3.6% for psychosis. Some of this discrepancy may be the result of the selection criteria of the meta-analysis (the authors used a time-frame of 6 months before imprisonment for assessing psychosis, not the 12 months used here and in NPMS-P: thus the review excluded the 3000 prisoners with high rates of psychosis in NPMS-P). It is also possible that the international studies used less rigorous techniques of sampling and interviewing, or that, in some jurisdictions, there was something idiosyncratic about prisons suitable for accommodating psychiatric surveys. We should emphasize that psychosis in both NPMS-P and ANPTP was identified by trained interviewers using a standardised psychiatric interview (SCAN). Our results for depressive episode were also higher than those obtained in the various international systematic reviews carried out by Fazel and colleagues [
13,
14,
30,
31], though the excess was less than for psychosis. Rates of depressive and anxiety disorders were similar in NPMS-P and the current study, though we found higher rates of PTSD in women.
High rates of psychiatric disorder might be expected in prisons like Holloway and Pentonville serving economically depressed inner city areas, as the social correlates of severe psychiatric disorder are very similar to those of criminal behaviour [
33]. However, NPMS-P, with equally high rates, sampled from all prisons in England and Wales.
Figures for hazardous drinking are appreciably higher than the general population rate, but those for alcohol dependence are three times as high in males and ten times in females. In contrast to the general population, there was no sex difference. Thus, alcohol problems are also skewed towards the more severe end of the spectrum in prisoners, particularly in women. Drug dependence was equally widespread, and our figures stand in starkest contrast to the general population, representing a 12-fold increase in men and 26-fold in women [
24].
Our overall prevalence rate for personality disorder was also high, with borderline personality disorder 33 times, and antisocial personality disorder 73 times more frequent than in the general population. Nevertheless, it was only half that in the NPMS-P sample [
6]. However, this may be because the method of identifying personality disorders was different: we used the full version of the SCID-II, whereas the NPMS-P data were based only on the screening version, increasing the possibility of false positives. The discrepancy with the systemic reviews carried out by Fazel and colleagues in relation to antisocial personality disorder (Table
3) may also be due to methods of assessment [
13,
31]. However, there was substantial heterogeneity between the included studies. This may originate from differences both in research methodology and in judicial policy.
Our data on comorbidity provide a final indicator of the burden of mental disorder in prisoners: in the general population, the sum total of disorders follows an exponential curve, with a majority having no disorders at all. Comorbidity was also very frequent in the meta-analysis of Fazel and Seewald [
13].
It should be noted that the differences between sentenced and remand prisoners were small. Only psychosis and personality disorder were commoner in remand prisoners than in their sentenced counterparts, though the difference was only significant for psychosis. This may represent some, limited, success in diverting offenders with psychosis from custodial sentences.
However, the English prison population rose by 64% between 1993 and 2011 [
34]. The rates of disorder in the current study are commensurate with those from NPMS-P more than 10 years previously. This implies a considerable absolute increase in the numbers of people with mental disorders in prison. It should be noted that the number of psychiatric beds declined by 44% over this period [
34].
If our values for psychosis are valid, and in particular if the UK is indeed an outlier in international terms, it suggests an idiosyncrasy in the way the justice system in the UK deals with people with serious mental illness. It implies that current approaches to management are unjust and inefficient. In their latest paper, Fazel and colleagues [
14] produce a comprehensive and plausible wish-list of suitable interventions in prisons. However, it is always difficult to deliver such treatments in the prison environment, and diversion is likely to be more efficient and just.