Do older adults respond to cognitive behavioral therapy as well as younger adults? An analysis of a large, multi‐diagnostic, real‐world sample

Older adults (OA; ≥55 years of age) are underrepresented in patients receiving cognitive‐behavioral therapy (CBT). This study evaluates mental health outcomes for OA compared to younger adults (YA; <55 years of age) receiving CBT.


| INTRODUCTION
Cognitive-behavioral therapy (CBT) is a proven treatment modality for anxiety and mood disorders in adults. [1][2][3] Previous studies have reported that CBT is effective in older adults (OA). Despite this, there is widespread ageism and a perception that OA will not benefit from CBT as much as younger adults (YA), and that OA are not as willing or able to discuss their mental health issues. [4][5][6] Thus, OA are less likely to be referred for therapy by their physicians, and more likely to be prescribed antidepressants. 7 Several studies have shown that older adults benefit from CBT, especially for depression and anxiety disorders (mainly generalized anxiety disorder). 4,8,9 Unfortunately, OA represent less than 10% of all CBT referrals. 5 There is still a large gap in the outcome literature on older adults, as most previous studies are with younger adults, and studies with community-dwelling older adults have small sample sizes or are often limited to specific diagnoses. [10][11][12][13][14][15][16][17] While these studies suggest that older adults do as well as younger adults, there is a need for larger studies exploring real-world outcomes of CBT treatment in community-dwelling older adults.
With that aim, we analyzed data collected over 20 years from a CBT service located in a university-affiliated tertiary care hospital. We compared the effectiveness of CBT for older adults and younger adults. We hypothesized that "real world" older patients would benefit less from CBT than younger patients, as a way to understand the disparity in referral rates.

| METHODS
Data analyzed in this study was collected between July 2001 and July 2021, as part of an ongoing prospective observational study of consecutive referrals for short-term CBT in the McGill University Health Centre (MUHC) CBT Unit. The MUHC CBT Unit is a specialized teaching unit, located in a tertiary care hospital. Patients are referred from physicians both within the hospital and from the general community.
The research ethics board of the McGill University Health Centre approved the study and reviewed the application annually.

| Participants
The sample for the present study consisted of 1500 patients referred for CBT for any diagnosis during the study period. The sample was then divided into a YA group (less than 54 years of age) and an OA group (55 years of age and older).

| Procedure
All patients underwent an initial telephone triage where preliminary diagnoses were recorded. They were then asked to fill out a set of validated symptom measures (BDI II, BAI, SCL90-R, SCID II selfreport), [18][19][20][21] as well as diagnostic questionnaires specific to their preliminary diagnoses. For example, patients referred for obsessivecompulsive disorder were asked to fill out the Yale-Brown Obsessive-Compulsive Scale 22 in addition to the above measures.
A subsequent 2-h clinical interview with a psychiatrist ascertained the precise clinical diagnoses using the prevailing Diagnostic and Statistical Manual of Mental Disorders that is, DSM-IV, DSM-IV-TR, DSM-5. [23][24][25] All primary, secondary, and exploratory data were collected at baseline and after CBT treatment.
Inclusion criteria were: (1) being over 18 years of age (2) willingness to engage in CBT, and (3) having a diagnosis for which there was evidence of CBT effectiveness. Exclusion criteria included requiring emergency or alternate psychiatric services.
The CBT administered in this study was problem-focused and employed standard, evidence-based techniques. Therapy was not manualized but guided using the individualized case conceptualization approach. 26 Patients were told therapy was short term, usually between 12 and 20 sessions, but all therapy endpoints were decided collaboratively. Trainee CBT therapists were from all mental health disciplines and included psychiatry residents, psychology interns, psychiatry fellows, and allied mental health professionals who were already experienced therapists getting additional training in the Center. All trainees received close individual supervision, and all therapy sessions were videorecorded for supervision and treatment integrity purposes. Selected videotapes were evaluated in their entirety to ensure competent CBT delivery using the Cognitive Therapy Rating Scale 27 or the Cognitive Therapy Scale Revised. 28 Complete protocol details have been previously published. 29

| Primary outcome measure
The primary outcome measure of this study was the Reliable Change Index (RCI). The RCI is a pre to post treatment change score, corrected for the reliability of a given diagnostic specific measure.
This provides a single continuous measure of outcome across a range of diagnoses. A value greater than 1.96 indicates that an observed change is statistically reliable, and not due to measurement error. 30 The full list of diagnosis-specific measures used is available upon request.

| Secondary outcome measures
Clinical significance A secondary outcome measure was a dichotomous variable indicating whether clinically significant change had occurred in the individual patient. If the patient's RCI was >1.96 (indicating statistically reliable change), and if the value of the post treatment test score was less than the "cut score" established for a given diagnostic measure, then clinically significant change was said to have occurred. This meant the patient no longer met the threshold for diagnosis of their condition. 30

RCI by diagnostic categories
To explore diagnosis-specific effects, RCI values for patients within different diagnostic categories were compared. The categories were: anxiety disorders, mood disorders, obsessive-compulsive (OCD) and related disorders, psychotic disorders and other disorders. This last category captured any disorder not included in the previous categories.

Clinical global impression and improvement
The Clinical Global Impression (CGI) assesses the overall severity of each patient's symptoms before and after treatment. Possible scores for severity range from 1 (normal, not at all ill) to 7 (among the most extremely ill patients). The CGI Improvement measure indicates the extent of change over the course of the therapy, ranging from 1 "Very much improved" to 7 "Very much worse". 31 Initial CGI values were the means of the assessment team member scores at intake.
Post-treatment severity and improvement values were entered by the treating therapist.

| Exploratory measures
Participants also completed the Symptoms Checklist-90-Revised (SCL-90-R), a 90 item self-report inventory where items are rated on a 5-point Likert scale of distress. 20 The Global Severity Index (GSI) from the SCL-90-R was used as a measure of general psychopathology.

| Statistical analyses
Data were analyzed using SPSS release 24 for Mac. The sample size for each analysis includes only those participants with complete data on the main outcome measure.
In this study, we are interested in comparing the mean difference in RCI, as well as the change of CGI, and SCL-90 subscales over time and between OA and YA. This can be done by using the ANOVA which is a statistical test to determine whether two or more population means are different. That is, the ANOVA is used to compare two or more groups to see if they are significantly different. 32 A one-way ANOVA with a two-factor design (age) was done to assess group differences in RCI between older adult (age >= 55) and younger adult (<55) groups. A two-way ANOVA was done to assess group differences between OA and YA in each diagnostic category group. Repeated measures ANOVA were used to test for group dif-  (Table 1) with no significant difference in proportion of trainees treating older versus younger adults.    Table 4 Table 5).

| DISCUSSION
In this study, we compared CBT outcomes in adults ≥55 years of after their CBT treatment.
The CGI severity and improvement scores also indicated improvement with time in both groups after treatment. However, both before and after treatment, CGI severity scores for older patients had lower values (i.e., OA had "milder" illnesses). Despite this, there were no interactions. This could reflect a selection bias in our sample in which only patients with a milder illness were selected.
Given that older adults are less likely to be referred for psychotherapy, 5 it could reflect that only "extremely good" older candidates were referred by their physicians. This is consistent with previous findings. 5 While this could have helped with therapy adherence, it also limited potential improvement by excluding the cases with more improvement to be gained. In any case, our CBT treatment effect remains robust for adults of all ages.

T A B L E 3 Reliable change indices by diagnostic categories in older versus
younger adults (older n = 99; younger n = 601).

Group Younger (<55) Older (≥55)
Mixed between-within ANOVAs (F) Category £ age Category Age Note: Description: Reports GSI total score, a severity measured derived from the subscales of the SCL checklist (higher scores = more psychopathology). Interpretation: Both younger and older people improved over time (had a lower GSI subscore). There were no significant differences between older and younger groups. There was no significant interaction effect.
-5 of 7 Our findings corroborate and extends the existing literature on CBT outcomes in older adults. To our knowledge, there has never been such a large non-veteran comparative study between older and younger adults. Most studies to date are limited by small sample sizes and have focused on single diagnoses (such as depression). [10][11][12][13][14][15][16][17] Our work adds to the literature on the potential effectiveness of CBT in older adults for less-studied disorders, such as obsessive-compulsive and related disorders.
In this paper, we show how CBT appears to benefit a diagnostically heterogenous sample of patients aged 55 years and older in the same way it helps those younger than 55 years of age.

| Limitations and strengths
There are some limitations to this study. A lot of the data collected comes from self-reported symptom questionnaires. A selection bias could have occurred, so that only the most motivated patients filled the questionnaires. This would be true of both groups, however. The questionnaires themselves reflect symptom burden, and do not directly touch upon the question of quality of life, which is a major concern for the elderly, and for all individuals with mental health disorders. While it is possible that quality of life is unchanged or worsened with CBT, a collaborative, problem focused therapy, is more likely to improve quality of life. Another possibility is that most of the patients are treated with trainee therapists; results may be expected to be lower than CBT practiced by professionals in the real world. However, these trainees are closely supervised, and treatment integrity checks ensure that structured CBT is being administered as described. This might lead to comparable results in the real world, where therapist "drift" is a known phenomenon. 33

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.