Study: A home-based cognitive training program improved cognition and mood in breast-cancer survivors with chemo fog
- Ten breast-cancer survivors with self-reported chemo fog completed a 45-minute, smartphone-based cognitive training program across 7 sessions in 15 days.
- Objective cognitive screening (CAB-CF) rose from 325.70 to 567.20, a 241.50-point gain (p < 0.001, Cohen’s d = −2.24).[1]
- Depressive symptoms (BDI-II) fell from 36.20 to 31.80 (p = 0.032) and cancer-coping (Mini-MAC) improved (p = 0.037); no adverse effects were reported in any session.[1]
- What it does not show: with no control group and only 10 participants over 7 sessions, this preliminary trial cannot prove the gains were caused by the training rather than by taking part in a clinical program.
Cancer survivors frequently report that their thinking changed after treatment, trouble retrieving words, holding concentration, multitasking or feeling mentally exhausted by the end of the day. This cluster, often called “chemo fog” or “chemo brain,” is common: cognitive impairment occurs in up to 80% of cancer patients at some point.5 About 40% of patients show cancer-related cognitive impairment (CRCI) right after diagnosis, rising to roughly 75% during chemotherapy and remaining near 60% months or even decades after treatment ends.3 With 5-year survival now around 70% and higher still for breast cancer, more women are living long enough to face these long-term effects.2
This 2023 study tested whether a self-administered, smartphone-delivered cognitive training program is safe and feasible for women who have survived breast cancer, and whether it produced measurable cognitive and emotional benefit in this trial’s participants.
What the study tested
The work was a Phase I/II clinical trial (registered as NCT05409248) run at the Breast Cancer Unit of the Hospital Universitario de la Ribera in Spain. Of 22 eligible patients, 13 (59.1%) enrolled; three withdrew, leaving a final Phase II sample of ten breast-cancer patients from a rural area, with a mean age of 51 years (range 35–67). To qualify, women had to have a histology-confirmed breast tumor, have completed chemotherapy at least one year earlier, report cognitive complaints, and be on hormone treatment with tamoxifen or aromatase inhibitors.[1]
A separate Phase I group of three participants first established the maximum tolerable dose using a 3 + 3 dose-escalation design. Training was delivered in 15-minute cycles of three 5-minute activities, with a fatigue questionnaire after each cycle. All three reported high fatigue (a score of 8 or higher on a 0–10 scale) after the fourth cycle, that is, after 60 minutes, so the session ceiling was set to the previous cycle: 45 minutes (varying between 40 and 45 minutes by participant).
Phase II then ran as a 15-day, pre/post intervention. A full assessment of cognition, daily functioning, emotional state and quality of life was performed on day 1 and day 15. Between those points participants completed seven training sessions (on days 2, 4, 6, 8, 10, 12 and 14, with a rest day between each), every session built from about nine activities of roughly 5 minutes, totalling the 45-minute target. The program ran remotely on the participants’ own smartphones using the CogniFit platform, whose Individualized Training System automatically tunes each task’s difficulty to the user’s performance. A clinical psychologist monitored progress online with daily contact.
Seven instruments tracked the outcomes. The primary measures were the mini-Mental Adjustment to Cancer Scale (Mini-MAC), the Functionality Assessment Instrument in Cancer Treatment–Cognitive Function (FACT-COG) and the Brief Fatigue Inventory (BFI). Secondary measures were the Cognitive Assessment for Chemo Fog Research (CAB-CF, a battery scored 0–800 across 17 activities), the Beck Depression Inventory (BDI-II), the State-Trait Anxiety Inventory (STAI, state subscale) and the WHOQOL-BREF quality-of-life questionnaire.
What it found
Safety came first: across both phases no participant reported negative effects or extreme fatigue in any Phase II session. On effectiveness, paired t-tests showed statistically significant pre-to-post change on three of the seven measures.
The largest signal was on the objective cognitive battery. The CAB-CF global score rose from a mean of 325.70 to 567.20, a gain of 241.50 points (t = 7.11, p < 0.001, Cohen’s d = −2.24). Cancer-coping, measured by the Mini-MAC, improved from 84.50 to 86.90 (t = 2.44, p = 0.037, d = −0.77). Depressive symptoms on the BDI-II fell from 36.20 to 31.80 (t = 2.52, p = 0.032, d = 0.80), and for the BDI-II a lower score means improvement.[1]
| Measure | Pre (day 1) | Post (day 15) | p | Cohen’s d |
|---|---|---|---|---|
| CAB-CF (cognition, 0–800) | 325.70 | 567.20 | < 0.001 | −2.24 |
| Mini-MAC (coping, 29–116) | 84.50 | 86.90 | 0.037 | −0.77 |
| BDI-II (depression, 0–63)* | 36.20 | 31.80 | 0.032 | 0.80 |
| FACT-COG (cognitive function, 0–148) | 80.30 | 86.10 | 0.411 | −0.27 |
| BFI (fatigue, 9–99)* | 21.00 | 17.60 | 0.278 | 0.36 |
| STAI-state (anxiety, 20–60)* | 45.90 | 43.40 | 0.082 | 0.62 |
| WHOQOL-BREF (quality of life, 28–140) | 90.80 | 91.40 | 0.838 | −0.06 |
*For BFI, BDI-II and STAI a lower score reflects an improvement in the evaluated domain.
The remaining four measures moved in the expected direction but did not reach significance: fatigue (BFI) dropped from 21.00 to 17.60 (p = 0.278), self-perceived cognitive function (FACT-COG) rose from 80.30 to 86.10 (p = 0.411), state anxiety (STAI) eased from 45.90 to 43.40 (p = 0.082), and quality of life (WHOQOL-BREF) was essentially unchanged at 90.80 to 91.40 (p = 0.838). A repeated-measures ANOVA found a significant main effect of evaluation test, F(1.23, 6.00) = 15.14, p < 0.003, η²p = 0.575, and showed the results did not correlate with participant age or with time since chemotherapy.[1]
Limitations
The authors are explicit that this is a preliminary, exploratory feasibility study, and several constraints limit how far the findings can travel. Most importantly, there was no control group: without one, the effect of the cognitive training itself cannot be separated from simply taking part in a supervised clinical intervention. The sample was small (n = 10) and varied in age, education and employment, and the program ran for only seven sessions, a low dose that the authors note further hinders generalization.[1]
There is also a transparency caveat: the data are not publicly available, owing to data-protection rules in the Spanish public health system. And while three of the seven outcomes reached statistical significance, the four that did not, including self-reported cognitive function, fatigue, anxiety and quality of life, mean the picture is encouraging rather than conclusive. The authors call for replication in larger samples with a longer-term view through randomized controlled trials.
Where this fits in the broader evidence
The findings line up with a wider literature: in this wider literature, cognitive training was generally reported to carry no detrimental effects and, in several studies, was associated with improved cognitive function and reduced depressive symptoms. The authors note that studies running more than one training session per week have consistently reported improvements, while benefits to quality of life remain uncertain across the field, consistent with the unchanged WHOQOL-BREF here. They position the trial as “one of the few studies” assessing the safety and efficacy of home-based computerized cognitive stimulation in people with cancer-related cognitive impairment. The authors framed the trial as adding to the case for studying digital cognitive-training tools in oncology.
For the full bibliography of CogniFit-related research and other studies in cognitive training, see the CogniFit research index.
References
- Effectiveness of a Computerized Home-Based Cognitive Stimulation Program for Treating Cancer-Related Cognitive Impairment. Int. J. Environ. Res. Public Health 2023, 20, 4953. https://doi.org/10.3390/ijerph20064953The focal study: a Phase I/II trial of 10 breast-cancer survivors; significant gains in cognition, coping and mood after 7 sessions, no adverse effects.
- Cancer Statistics, 2023. CA Cancer J. Clin. 2023, 73, 17–48.Source for the ~70% 5-year relative survival estimate.
- Longitudinal Trajectory and Characterization of Cancer-Related Cognitive Impairment in a Nationwide Cohort Study. J. Clin. Oncol. 2018, 36, 3231–3239.
- Cognitive Complaints in Survivors of Breast Cancer After Chemotherapy Compared With Age-Matched Controls. J. Clin. Oncol. 2017, 35, 506–514.
- Prevalence of Cognitive Impairment Following Chemotherapy Treatment for Breast Cancer: A Systematic Review and Meta-Analysis. Sci. Rep. 2022, 12, 2135.
- Cognitive Impairment in Patients With Breast Cancer: Understanding the Impact of Chemotherapy and Endocrine Therapy. J. Clin. Oncol. 2020, 38, 1871–1874.