A Reverse Flynn Effect: Trends in Six Decades of Neuropsychological Data in a UK High Security Population

A Reverse Flynn Effect: Trends in Six Decades of Neuropsychological Data in a UK High Security Population

In a sample of adult patients admitted to a High Secure Psychiatric Care hospital in the United Kingdom over the span of six decades, the majority of the patients had a full scale IQ that in the ‘low average’ and ‘extremely low’ categories. In addition, processing speed was the most compromised area of cognitive functioning and a one standard deviation decline in the overall IQs of patients was observed. This is the bottom line of a recently published article in The International Journal of Forensic Mental Health. Below is a summary of the research and findings as well as a translation of this research into practice.

Featured Article | International Journal of Forensic Mental Health | 2021, Vol. 20, No. 4, 386-397

Weschler Adult Intelligence Scale Full Scale IQ of Male Admissions to a High Secure Psychiatric Hospital Over Six Decades


David Murphy, West London NHS Trust
Joanna Mitchell, Broadmoor Hospital
Joseph Vacher, Broadmoor Hospital
Emily Jane Morley, Broadmoor Hospital
Ignazio Puzzo, Brunel University London


The present study describes the Wechsler Adult Intelligence Scale (WAIS) full scale IQ (FIQ) of admissions to one UK High Secure Psychiatric Care hospital. WAIS IV comparative data and the FIQ of admissions from the 1960s to the 2010s are presented (n = 639). Results suggest 75% of current admissions have FIQs within the ‘low average’ and ‘extremely low’ classifications, with significant discrepancies between composite scales being common and processing speed being the most compromised area of cognitive functioning. A one standard deviation decline in FIQs of admissions since the 1960s to the 2010s is also present. The results are discussed in terms of the changing clinical presentations of admissions, along with research and clinical implications.


High secure psychiatric care, Intelligence, Weschler Adult Intelligence Scale

Summary of the Research

“The most widely used test of adult intelligence among neuropsychologists and forensic psychologists is the Weschler Adult Intelligence Scale (WAIS), designed to measure cognitive ability in individuals 16 years old and above…Within the UK, HSPC is the highest level of adult secure psychiatric care. All admissions are 18 years old or older, considered to present with a grave and immediate risk of harm to others, as well as viewed as having a mental disorder as defined by the Mental Health Act…and requiring hospital treatment…Within one HSPC hospital, psychological archives suggest that cognitive assessments date back to at least the 1940s…Although the complexity of neuropsychological examinations has increased over the years, the [WAIS] has remained the cornerstone of these assessments…despite the WAIS being routinely administered, there has been little examination of how individuals admitted to HSPC perform specifically in the WAIS…” (p.387-388).

“Within the context of the limited background literature on WAIS profiles of forensic psychiatric populations, the study set out to: 1) Describe the WAIS IV profiles of male patients admitted to one HSPC hospital…in line with previous research, it was expected that processing speed would be the most compromised area of cognitive functioning in admissions; 2) Describe the WAIS full scale IQs of admissions within a historical context…it was expected that the average full IQ of admissions would follow the increase over the decades as observed in the general population; 3) Describe the number of admissions to the hospital with full scale IQs two standard deviations below the mean over these six decades. This analysis was exploratory with the intention of examining the number of admissions who meet the cognitive criteria for having a learning disability (LD)…” (p. 388-389).

“639 male admissions were examined for analysis from the six decades since 1962…105 WAIS IV profiles were examined, with assessments being completed between 2009 and 2019…The finding that the majority of contemporary admissions to HSPC (62%) present with WAIS IV full scale IQs falling in the ‘borderline’ and ‘low average’ ranges, along with the 15% whose full scale IQ fall in the ‘extremely low’ range suggest suboptimal levels of cognitive functioning are typical in the current population. However, the quarter of admissions who present with full scale IQs falling in the ‘average’ or ‘high average’ range suggest overt cognitive dysfunction is not true for all…Of significance is the application of the Flynn adjustment to full scale IQs which suggests individuals admitted may be less able than the WAIS IV manual data suggests…” (p.389-391).

“…Consistent with the literature…the examination of the WAIS IV composite profiles and subtests suggest that processing speed (specifically the subtests of coding and symbol search) is the most compromised compared to other areas of cognitive functioning. However, this finding should be treated with caution…Contrary to the observation that full scale IQs appear to have increased in the general population is the finding that the full scale IQs of the current sample over the six decades has significantly reduced, with a one standard deviation drop between those admitted during the 1960s and 2010s. This suggests that contemporary admissions present with more cognitive dysfunction compared to admissions from previous decades…Whatever the potential explanations for the reduction in general levels of intellectual functioning, a reverse Flynn effect appears to have occurred in his population…” (p.392).

Translating Research into Practice

“…The presence of high levels of cognitive dysfunction among admissions to HSPC as reflected by low levels of general intellectual functioning and notably processing speed difficulties suggest the consideration of an individual’s cognitive functioning remains important. As well as all clinical staff making reasonable adjustments and adaptations to everyday procedures to minimize the effects of any cognitive dysfunction, specific application and evaluation of cognitive remediation interventions for those who might benefit from targeting cognitive problems is required, especially those directed at processing speed…Including cognitive dysfunction awareness in staff training on mental illness is also essential as clinical impressions suggest such knowledge is lacking in many staff…” (p.394).

“In terms of clinical assessments and interventions, full scale IQ continues to be requested for many individuals to inform future clinical pathways notably to [obtain] intellectual disability services and is often associated with requests for repeat IQ testing. Such situations can create much debate as to an individual’s level of difficulties and ignores research evidence suggesting repeat IQ testing in forensic intellectual disabilities is associated with significant inconsistency between scores…and where IQ may not be a reliable indication of an individual’s level of functioning…It could be argued that the results also support the continued need for routine neuropsychological assessments of admissions into HSPC. Not only do such assessments provide useful clinical information regarding an individual’s functioning and specific needs, they assist with monitoring the changing clinical presentation of the population…” (p.394).

Other Interesting Tidbits for Researchers and Clinicians

“…Among the many theories and definitions of intelligence put forward, it has been Spearman’s (1904) concept of ‘g’ or general factor theory (that there is a broad mental capacity that individuals possess which influences performance on cognitive ability measures) that has been widely adopted, followed by Cattell’s (1943) idea of ‘fluid’ (ability to solve novel problems by using reasoning) and ‘crystalized’ (knowledge based ability) intelligences. In terms of the assessment of intelligence, the majority of tests aim to assess these forms of intelligence and quantify ‘g,’ with most using the concept of an ‘intelligence quotient’ (IQ)…Regardless of the method used for assessing intelligence is the observation that during the twentieth century the full scale IQ of the general population has steadily increased by approximately three points every decade (Flynn, 2009). In order to compensate for this increase, it has also been suggested that a calculated full scale IQ needs to be adjusted by deducting 0.3 points for every year since the collection of the comparative data used…” (p.386).

“…Whilst the increasing complexity and demands of each version of the WAIS test may account for some of the reduction in full scale IQ…other contributing factors must also be at work. Of particular significance is the gradual change in presenting characteristics of admissions into HSPC, notably higher levels of mental disorder, interpersonal risks to others and an associated increase in the level of cognitive disturbance…The finding that current admissions to HSPC present with lower levels of ‘intelligence’ compared to previous generations is particularly interesting within the context of the wider changes in society where general levels of intellectual functioning…are thought to have increased due to improved early nutrition, education, literacy levels and general standard of living…Although speculative, it could be argued that whilst many admissions to HSPC during the 1960s would have experienced considerable social deprivation within the context of a postwar Britain, current admissions are exposed to other factors that have a detrimental impact on cognitive development and functioning, notably early and possibly sustained polysubstance misuse by themselves and possibly by their mothers when pregnant…as well as many growing up in urban environments with high levels of air pollution…” (p. 392-293).

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Authored by Amber Lin

Amber Lin is a clinical psychology doctoral student at Fairleigh Dickinson University. Her research interests include forensic assessment, competency to stand trial, and the refinement of instruments used to assess the psychological states of criminal defendants.

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