Significant diversity was noted among the 12 studies on a range of parameters. Seven studies included only participants diagnosed with AD, but the other four included participants diagnosed with AD, vascular dementia or mixed dementia. In one study (Quayhagen 2000), participants were included if they were diagnosed with dementia due to Parkinson's disease (PD) in addition to AD and vascular and mixed dementia, but it was not possible to ascertain how many of the included participants had PD, because data for all aetiologies were reported together. Severity of dementia varied in the included studies from very mild to moderate; this was generally determined on the basis of scores on a measure of dementia severity or global cognition (e.g. Clinical Dementia Rating, MMSE). Although not stated explicitly in most studies, it appears that in most cases, patients were recruited from the community; in a small number of studies, patients who resided in residential care homes were also included. The duration of interventions provided in the included studies varied considerably, ranging from 4 to 24 weeks. Four studies reported follow-up assessments over the medium term; these occurred at 8 weeks, as well as at 3, 6 and 9 months, after the end of treatment. The content of the interventions also varied considerably, ranging from training in the use of compensatory strategies to practice on computerised tasks to working toward achieving collaboratively derived goals. Selected features of the included studies are further described here and are summarised in the Characteristics of included studies table.
Objectives of the studies
Beck 1988: Compared 'cognitive skills remediation training', delivered on a one-to-one basis, with a usual-treatment control condition.
Heiss 1993: Compared computerised cognitive training alone with two conditions in which computerised cognitive training was combined with drug treatment (cognitive training plus pyritinol and cognitive training plus phosphatidylserine) and an active control condition (social support). The relevant comparison for this review is that between cognitive training alone and social support.
Quayhagen 1995: Compared cognitive training with active and wait-list control conditions. The relevant comparison for this review is that between cognitive training and the wait-list control condition.
de Vreese 1998: The study initially set out to compare cognitive training alone, acetylcholinesterase-inhibiting medication (AChEI) alone, cognitive training plus AChEI and placebo. Raw data for the group receiving cognitive training alone were not reported in the 1998 paper and are no longer available. The design was subsequently amended as caregivers were dissatisfied with the possibility of receiving cognitive training alone, so the comparisons reported in 2001 and augmented with further information from the author involve three groups: AChEI alone, cognitive training plus AChEI and active control. For the purposes of this review, the comparison of interest lies in the difference between AChEI alone and cognitive training plus AChEI.
Quayhagen 2000: Compared four intervention approaches－cognitive training, dyadic counselling, dual supportive seminar groups and early-stage day care with caregiver support－with a wait-list control condition. For the purposes of this review, the comparison of interest is that between cognitive training and the wait-list control condition.
Davis 2001: Compared cognitive training with a 'mock' (active control) intervention in a cross-over design. The comparison of interest is that between training and active control groups following the initial intervention stage; cross-over data are not considered here.
Koltai 2001: Compared a memory and coping programme, delivered in individual or group session format, with a wait-list control condition. The results for individual and group training were analysed together in the trial report as no differences were observed between them.
Cahn-Weiner 2003: Compared a memory training programme delivered in small-group format with a control condition involving didactic presentation.
Loewenstein 2004: Compared 'cognitive rehabilitation training' with 'mental stimulation', delivered in one-to-one sessions.
Galante 2007: Compared individual computerised cognitive training with an active control condition.
Neely 2009: Compared collaborative cognitive training (dyadic), individual cognitive training and a no treatment control condition. The relevant comparison for this review is that between individual cognitive training and no treatment groups.
Clare 2010: Compared individual, goal-oriented cognitive rehabilitation with relaxation therapy, and with a no treatment control condition. The relevant comparison for this review is that between the cognitive rehabilitation and no treatment groups.
Participant numbers and characteristics in the overall samples
Beck 1988: Participants included 20 individuals over 55 years of age with moderately impaired cognitive functioning (MMSE score of 15 to 20) and findings compatible with a diagnosis of Alzheimer's disease or mixed dementia, living in one of four nursing homes or in the geriatric unit of a Veterans Administration hospital.
Heiss 1993: Of 80 people who entered the study, data were available for 70. Included in this group were 37 men and 33 women with a diagnosis of possible or probable AD according to NINCDS-ADRDA criteria and a modified Hachinski score of 3 or less, ranging in age from 48 to 79 years (average age 66.63 years), and with MMSE scores ranging from 13 to 26. On entry to the study, none were taking any medications known to affect the central nervous system. This study was carried out in Germany.
Quayhagen 1995: Of 135 care recipient/caregiver dyads initially assessed, 95 were eligible for inclusion, 79 completed the study and data were available for 78. These were families in which one person had a diagnosis of possible/probable AD and was in the mild or moderate stage with a Mattis Dementia Rating Scale (DRS) score of 90 or above. People with dementia included 51 men and 27 women, with an average age of 73.6 years (standard deviation (SD) 8.0) and an average education level of 12.6 years (SD 4.1). They were not participating in any clinical trials of anti-dementia medication. Caregivers consisted of 18 men and 60 women, with an average age of 66.7 years (SD 10.8) and an average education level of 14.1 years (SD 2.7). Twenty-nine percent of caregivers attended support groups periodically, and 14% had previously sought psychological help. This study was conducted in California, USA, and ethnicity within the whole sample was described as 85% white, 3% African American and 11% Hispanic.
de Vreese 1998: The 1998 paper reports the inclusion of 24 participants with a diagnosis of AD according to NINCDS-ADRDA orDSM-IV criteria and a CDR rating of 1 to 2. Average age was 72.6 years (range 61 to 83 years). The 2001 review paper reports the inclusion of 27 participants with early-stage AD and MMSE scores ranging from 20 to 26, representing the removal of the 6 people in the original cognitive training alone condition and the addition of 3 more participants to each of the other groups. Participants were taking no concurrent medication known to affect the central nervous system. This study was undertaken in Italy.
Quayhagen 2000: Participants included 103 dyads consisting of a person with dementia and a caregiving spouse. The people with dementia had a diagnosis of possible or probable AD (more than 70% were in this category), vascular dementia or Parkinson's dementia, and were in the mild or moderate stages, scoring above 100 on the DRS. They included 65 men and 38 women, with an average age of 74.51 years (SD 7.11) and an average education level of 14.57 years (SD 3.05). The caregivers were 38 men and 65 women, with an average age of 71.83 years (SD 8.12) and an average education level of 14.42 years (SD 3.05). The study took place in California, USA, and the ethnic mix within the whole sample was described as 93% white, 2% African American, 1% Asian and 4% Hispanic.
Davis 2001: The participants were 37 individuals (16 men and 21 women) with a diagnosis of probable AD according to NINCDS-ADRDA criteria. MMSE score range was 15 to 29 (average score 22.31). Average age in the sample was 70.62 years, and average level of education was 14.02 years. Mean score on the 30-item Geriatric Depression Scale (5.02) was within the normal range. This study was carried out in Texas, USA.
Koltai 2001: The participants were 24 older people aged 60 to 84 with a diagnosis of AD and a CDR score of 0.5 or 1.0. Of the 25 people initially identified as eligible, one found the group treatment modality unacceptable and declined to take part. The study was carried out in North Carolina, USA.
Cahn-Weiner 2003: The participants were 34 individuals (20 women and 14 men) with a diagnosis of probable AD according to NINCDS-ADRDA criteria. The study was conducted in Rhode Island, USA.
Loewenstein 2004: The participants were 44 individuals (26 men and 18 women) with a diagnosis of probable or possible AD according to NINCDS-ADRDA criteria. The authors note that those with a diagnosis of probable AD met DSM-IV criteria for dementia, and those with possible AD did not show sufficient functional impairment to merit a DSM-IV diagnosis of dementia. All participants had been on a stable dose of an acetylcholinesterase inhibitor for 8 weeks at the start of the study; 41 of these were taking donepezil (doses ranged from 5 to 15 mg). Approximately two-thirds of participants were English speakers, and the remaining 14 were Spanish speakers, mostly of Cuban origin, for whom all components of the programme were conducted in Spanish. The study took place in Florida, USA.
Galante 2007: Participants were 12 individuals who met NINCDS-ADRDA criteria for mild AD and scored 19 to 26 on the MMSE or 70 to 90 on the Milan Overall Dementia Assessment (MODA). All were treated with AChEI for at least 3 months. The mean age of the sample was 76 years (SD 6), and the mean educational level was 6.3 years (SD 2.2). One control participant was excluded from analysis "due to poor compliance". The study was conducted in Italy.
Neely 2009: Forty-seven individuals who met DSM-IV criteria for mild to moderate AD or vascular dementia and their spouses were approached for the study, and 30 patients (15 males, 15 females) consented to participate. All participants were diagnosed with dementia within the 8 months immediately before the study, were living at home with their spouses and were free from significant psychiatric disorders. The mean age of patients was 75.4 years (SD 6.4). The study was conducted in the Stockholm area of Sweden.
Clare 2010: Participants were 69 individuals (41 women, 28 men) with a mean age of 77.78 years (SD 6.32), and a mean education level of 10.64 years (SD 1.67). They were diagnosed with AD (n = 56) or mixed AD and vascular dementia (n = 13) according to NINCDS-ADRDA criteria. The mean MMSE score was 23 (SD = 3.02), and all participants were on a stable dose of AChEIs. Forty-four participants had family members involved, and in all but 4 cases, these individuals were living with the person with dementia. The study was conducted in the North Wales area of the UK.
Characteristics of participants in the treatment and comparison groups
Beck 1988: Characteristics of participants in the treatment and control groups are summarised in Table 1. No significant differences were found between the two groups. Each group comprised 7 white and 3 black participants. In the treatment group 2 had completed grade school, 6 high school and 2 college, and in the control group, 2 had completed grade school, 7 high school and 1 college. In the treatment group 6 people resided in nursing homes and 4 in hospital, and in the control group 9 people resided in nursing homes and 1 in hospital.
Table 1. Summary characteristics of participants in cognitive training and control groups
Age mean (SD),
|Gender balance (m:f)||Years of education||Number taking AChE-I|
| Beck 1988||Cognitive training||10||74 (range 68-75)||5:5||Attended college = 2||none||not reported||0|
| ||Control||10||76 (range 70-93)||3:7||Attended college = 1||none||not reported||0|
| Heiss 1993||Cognitive training|
not reported (18
completed the study)
|65.9 (6.28)||9:9||not reported||none||20.55 (4.42)||not reported|
not reported (17
completed the study)
|66.6 (10.17)||10:7||not reported||none||20.23 (4.10)||not reported|
| Quayhagen 1995||Cognitive training||25||not reported||not reported||not reported||not reported||not assessed||not reported|
| ||Control||25||not reported||not reported||not reported||not reported||not assessed||not reported|
| de Vreese 1998||Cognitive training||9||not reported||not reported||not reported||all||17.33 (3.39)||0|
| ||Control||9||not reported||not reported||not reported||all||17 (3.2)||0|
| Quayhagen 2000||Cognitive training||21||not reported||not reported||not reported||not reported||not assessed||not reported|
| ||Control||15||not reported||not reported||not reported||not reported||not assessed||not reported|
| Davis 2001||Cognitive training||19||68.67 (3.86)||10:9||15.06 (3.86)||5||21.84(4.03)||0|
| ||Control||18||72.56 (7.62)||6:12||12.97 (2.56)||4||22.78 (4.45)||0|
| Koltai 2001||Cognitive training||16||72.9 (6.7)||not reported||15.0 (4.0)||not reported||22.9 (3.6)||2|
| ||Control||8||73.9 (7.2)||not reported||15.0 (4.0)||not reported||26.6 (2.5)||0|
| Cahn-Weiner 2003||Cognitive training||19||77. 8 (6.9)||9:8||12.7 (2.1)||all||24.3 (2.2)||2|
| ||Control||20||76.0 (7.7)||5:12||13.1 (3.5)||all||25.1 (1.7)||3|
| Loewenstein 2004||Cognitive training||28||78.12 (4.3)||15:10||13.08 (4.1)||all||23.4 (2.9)||3|
| ||Control||21||74.74 (7.5)||11:8||14.37 (3.0)||all||24.53 (4.5)||2|
| Galante 2007||Cognitive training||7||not reported||not reported||not reported||all||22.9 (3.1)||0|
| ||Control||4||not reported||not reported||not reported||all||23.1 (1.8)||1|
| Neely 2009||Cognitive training||10||74.8 (6.7)||6:4||not reported||not reported||22.9 (4.15)||0|
| ||Control||10||77.0 (6.6)||6:4||not reported||not reported||18.6 (5.7)||1|
| Clare 2010||Cognitive rehabilitation||22||76.3 (6.39), 64-89||9:13||11.41 (2.81), 9-19||all||23.14 (3.12), 18-27||2|
| ||Control||22||78.1 (6.61), 56-87||9:13||11.43 (2.99), 9-19||all||22.32 (3.05), 18-30||1|
Heiss 1993: Mean ages and gender distributions for cognitive training and social support conditions are summarised in Table 1. No significant differences were noted between groups.
Quayhagen 1995: Details are not reported separately for the cognitive training and comparison groups, but the authors comment that no significant differences were observed between groups.
de Vreese 1998: In the 1998 paper, groups were reportedly matched on educational level and illness severity, although the cognitive training plus AChEI group had a significantly longer duration of illness. The 2001 paper reports that groups were matched on MMSE scores; mean MMSE scores are reported in Table 1.
Quayhagen 2000: Details are not reported separately for the cognitive training and comparison groups, but the authors comment that no significant differences were noted between groups.
Davis 2001: Characteristics of participants in each of the two groups are summarised in Table 1. No statistically significant differences were reported, but some trends were apparent; participants in the cognitive training group were on average younger and better educated and were more likely to be male and to be receiving anti-depressant medication.
Koltai 2001: Characteristics of participants in training and control groups are summarised in Table 1. Participants in the control group had significantly higher MMSE scores at baseline (26.6 vs 22.9) and significantly lower relative rated levels of depression on the Geriatric Depression Scale (GDS) (8.3 vs 14.7).
Cahn-Weiner 2003: Characteristics of participants in each of the two groups are summarised in Table 1. No statistically significant differences were noted between the groups on these parameters.
Loewenstein 2004: Characteristics of participants in each of the two groups are summarised in Table 1. No statistically significant differences were noted between the groups on these parameters, except that three-month follow-up was significantly later for the cognitive training group (13.67 weeks from post-intervention, compared with 12.79 for the mental stimulation group).
Galante 2007: The authors provided the mean age and education level for the full sample, but no information regarding these patient characteristics was provided at the group level. In addition, the authors report in a table the means and SDs for the two groups on the cognitive measures at all time points, but significance levels are provided only for the Time × Group interaction. Therefore, it is not possible to ascertain whether the groups were equivalent at baseline. Visual inspection shows clear trends for group differences on a number of cognitive (e.g. prose memory), functional (e.g. instrumental activities of daily living (IADL)) and mood (e.g. Neuropsychiatric Inventory (NPI)) measures at baseline. Available characteristics of participants in the training and control groups are summarised in Table 1.
Neely 2009: Relevant characteristics of the treatment and control groups are summarised in Table 1. The groups did not differ in age, levels of depression, MMSE scores or subjective health, or on any of the cognitive measures included at baseline. Data on participants' education level was not reported.
Clare 2010: Characterisitcs of the intervention and control groups are summarised in Table 1. No group differences were found at baseline in any of the demographic, cognitive or functional measures or in the presence of comorbid medical conditions.
Description of the interventions
Beck 1988: Cognitive skills remediation training included exercises on attention and reading, concentration on detail and remembering. Exercises were graded for difficulty level, and participants were given assistance when they had problems with the tasks.
Heiss 1993: Computerised cognitive training for one hour, twice a week, with commercially available software designed for use in neurological rehabilitation (produced by Rigling Reha-Service), running on a Commodore C64 computer. Participants had to solve memory, perceptual or motor tasks, selected according to the profile of cognitive impairment, of varying difficulty levels. Duration of training was 24 weeks.
Quayhagen 1995: One hour per day of active cognitive stimulation, six days per week, facilitated by the family caregiver in the home setting, using ecologically valid exercises addressing memory, problem-solving and conversational fluency. A workbook provided for family caregivers contained exercises of varying difficulty levels from which they could select appropriate tasks. The exercises were continued for 12 weeks.
de Vreese 1998: Twice-weekly, 45-minute individual sessions with caregivers present, aimed at '(re)training memory (in particular autobiographical and implicit), language and executive abilities associated with reality orientation therapy, to be repeated at home by the caregiver'. The 2001 paper describes the sessions as 30 to 40 minutes in length and involving individually tailored memory training exercises that provided support for encoding (use of real-life material, involvement of motor activity, self-generation of cues) and for retrieval (provision of supplementary cues, use of forced-choice recognition). The sessions were introduced after a 3-month run-in period on the drug treatment and were continued for 12 weeks.
Quayhagen 2000: As for Quayhagen 1995, but given 5 days per week for 8 weeks. Post-treatment assessment was carried out at 12 weeks.
Davis 2001: Weekly individual one-hour sessions at the clinic, covering (1) spaced retrieval training for personal information (although half recalled the information without training, so there was a ceiling effect); (2) the 'peg' task mnemonic strategy (for those who required little or no spaced retrieval training) and (3) face-name association using mnemonics. Home attention exercises were carried out for 30 minutes per day, 6 days a week, and were directed by the caregiver. Duration of treatment was five weeks.
Koltai 2001: The memory and coping programme was delivered in individual or group modality. The group format consisted of five weekly, one-hour sessions conducted in groups of four. The individual format consisted of a mean of six individual sessions. Caregivers joined the last 10 to 15 minutes of each session, where available. The programme involved training and practice in the following techniques: spaced retrieval, face-name recall, verbal elaboration, concentration/overt repetition, external memory aids and coping strategies.
Cahn-Weiner 2003: The memory training provided was a modified version of a manualised protocol, involving practice with memory strategies such as categorisation and visualisation and word list learning.
Loewenstein 2004: The cognitive rehabilitation training covered time and place orientation, face-name association learning, object manipulation, attention and visuomotor training with a computer, making change for a purchase from a $20 bill and balancing a cheque book. Participants were encouraged to use a memory notebook and to practice what they had learned at home between sessions.
Galante 2007: The computerised cognitive training group was trained on a set of computerised exercises selected from a software package covering the domains of memory, language, perception, attention, spatial cognition and intelligence. Exercises were administered in a fixed sequence to all participants, and most exercises lasted 3 minutes.
Neely 2009: The cognitive training was conducted with the support of a research assistant. Participants were trained on a name-face learning task and on a table-setting activity. Spaced retrieval and the provision of letter cues were used to support training on the face-name learning task, whereas a hierarchical cueing technique was used to support training on the table-setting activity.
Clare 2010: The focus of the intervention was addressing personally meaningful goals; goals were collaboratively identified, and individualised interventions were developed. This was supported by the provision of practical aids and strategies, techniques for learning new information, practice in maintaining attention and concentration and techniques for stress management. Participants were encouraged to work on goals and practise strategies between intervention sessions, and caregivers were invited to participate in the final 15 minutes of each session to assist with between-session implementation.
Length and duration of the interventions
A summary of the duration of interventions and the timing of assessments is shown in Table 2.
Table 2. Summary of duration of interventions and timing of assessments
|Study||Intervention length||Initial assessment||Interim assessment||Post-interv assessment||Follow-up assessments||Details of sessions||Format of sessions|
| Beck 1988||6 weeks||week 0||n/a||week 6||n/a||18 × 30- to 40-minute sessions||Individual|
| Heiss 1993||24 weeks||week 0||weeks 8 and 16 (plus monthly physician appointments)||week 25||n/a||48 × 1-hour sessions||Individual|
| Quayhagen 1995||12 weeks||week 0||n/a||week 13||week 38||72 × 1-hour caregiver-facilitated sessions||Individual|
| de Vreese 1998||12 weeks (after 12 weeks on drug)||weeks 0 and 13||n/a||week 26||n/a||24 × 45-minute sessions||Individual|
| Quayhagen 2000||8 weeks||week 0||n/a||week 12||n/a||40 × 1-hour caregiver-facilitated sessions||Individual|
| Koltai 2001||5 to 6 weeks||weeks 0 to 2||n/a||weeks 6 to 8||n/a||5 × 1-hour sessions (group) or mean of 6 × 1-hour sessions (group)||Group or individual|
| Davis 2001||5 weeks||week 0||n/a||week 6||week 12 (cross-over)||5 × 1-hour sessions||Individual|
| Cahn-Weiner 2003||6 weeks||week 0||n/a||weeks 8 to 9 (mean 59 days post-baseline)||week 16 (mean 114.5 days post-baseline)||6 × 45-minute sessions||Group|
| Loewenstein 2004||12 to 16 weeks||week 0||n/a||weeks 13 to 18||weeks 25 to 31||24 × 45-minute sessions||Individual|
| Galante 2007||4 weeks||week 0||n/a||week 5||3, 6 & 9 months (MMSE only) post-interventions||12 × 60-minute sessions 3 times per week||Individual|
| Neely 2009||8 weeks||week 0||n/a||week 9||n/a||8 × 60-minute sessions||Dyads or Individual|
| Clare 2010||8 weeks||week 0||n/a||week 9||6 months||8 × 60-minute sessions||Individual|
Beck 1988: The intervention was delivered in one-to-one sessions lasting 30 to 40 minutes, held three times a week for six weeks.
Heiss 1993: Twice-weekly, one-hour individual sessions for 24 weeks.
Quayhagen 1995: One hour per day, 6 days per week, for 12 weeks, facilitated by caregiver, plus weekly session with member of research team.
de Vreese 1998: Twice-weekly 45-minute individual sessions for 12 weeks, supplemented by home practice.
Quayhagen 2000: One hour per day, 5 days per week, for 8 weeks, facilitated by caregiver, plus modelling of the intervention by member of the research team to assist the caregiver.
Davis 2001: Weekly individual one-hour sessions for 5 weeks, supplemented by home practice, 30 minutes per day, 6 days per week.
Koltai 2001: The group format consisted of five weekly, one-hour sessions conducted in groups of four. The individual format consisted of a mean of six individual sessions. Caregivers joined the last 10 to 15 minutes of each session where available. As no differences were observed in results for group and individual training, the data were analysed together.
Cahn-Weiner 2003: Weekly small-group sessions lasting 45 minutes each, over a 6-week period.
Loewenstein 2004: The interventions were delivered in 24 individual sessions, each lasting 45 minutes over a 12- to 16-week period.
Galante 2007: The intervention was delivered individually, with each participant receiving twelve 60-minute sessions, three times a week, over 4 weeks,
Neely 2009: Participants were offered a one-hour session of home-based training each week for a period of 8 weeks.
Clare 2010: Cognitive rehabilitation was delivered in eight weekly, 1-hour individual sessions conducted in participants' homes.
Description of the comparison conditions
Beck 1988: Participants in the control condition received treatment as usual with no additional intervention.
Heiss 1993: The social support condition consisted of weekly, one-hour individual sessions that included conversation about personal problems in managing daily life, as well as past experiences, sometimes assisted by games. It is not clear whether the sessions were carried out individually or in groups.
Quayhagen 1995: Placebo intervention consisted of similar types of caregiver-facilitated exercises, offered for an equivalent length of time but designed to elicit only passive responses rather than active processing and engagement.
de Vreese 1998: Participants received AChEI medication alone for a 6-month period.
Quayhagen 2000: Wait-list control condition.
Davis 2001: 'Mock' intervention involved five weekly, one-hour individual sessions comprising unstructured conversation, recitation of 'overlearned material' and watching of health-related videos.
Koltai 2001: Wait-list control condition.
Cahn-Weiner 2003: The comparison condition was an educational group intervention in which didactic information about ageing and dementia was provided.
Loewenstein 2004: The mental stimulation intervention included individual sessions comprising computer games, exercises like 'hangman', word-finding tasks and discussion of the 'topic of the day'.
Galante 2007: Participants in the nonspecific treatment condition participated in a semi-structured interview on current affairs and relevant events of their own life history. The neuropsychologist who conducted the sessions made use of audiovisual material and information received from participants and their relatives on the participant's life history, hobbies and favourite activities. The control condition was matched with the intervention group in terms of number, duration and frequency of sessions.
Neely 2009: Participant dyads in the control condition did not receive any intervention between the pretest and the post-test.
Clare 2010: Participants in the 'no treatment' group had no contact with the research team between baseline and post-intervention assessments.