Memory at work

Patients seem to take longer to 'come online' in ongoing conversation, and holding on to direction in a task. A pause is too long, disturbing current interchange, and ongoing interchange Initiated by the sufferer, conversation holds together better

Ordinarily what happens is for the next moment - or what will come up during the next day, has been prepared for; a readiness is there.
A memory bank context is held ' in mind': something ... the Will ... keeps it going, holds it relevantly to both the initial point, and updating it as things come after that starting point. Extraneous 'noise' is kept away. [ rather as the answer to a crossworld puzzle clue can be answered later when [ the point ] it could not be done earlier - something silent has kept a search going.

prospective memory

Three other Memory Studies in schizophrenia point the way to rehabilitation .... and a try at repair

A.

The authors hypothesized that patients with schizophrenia would have problems with tasks requiring prospective memory.

They might mistake remembering they have to do something with remembering they've actually done it.

Their hypothesis stemmed from the theory that people with schizophrenia confuse real ( 'outside' ) concrete acts, things, which they are impelled to notice, [ passivity - can't keep out intrusive thoughts or outside connections that seem to force in ] with 'internal thinking'... 'constructive day dreaming ' ) thought 'events'.

[ what does this mean ?
...maybe ...that they do not hold to an internally intended direction, but are distracted by inappropriate external or internal associations, not really wanted, so that they lose track and are taken over by those associations and instead of going on with a task, lose the point or lose the anchoring internal guide ]

They don't hold together the background information that is necessary to continue without mistakes. In tasks, jobs, and in living.

Patients with schizophrenia must take medication regularly to reduce their risk of relapse.

But the condition impairs working memory - meaning these patients may have difficulty in remembering to take their tablets.

Habitual tasks, like taking medicine every few hours, rely on "'prospective' memory". that is, a scheduled signal laid down and stored away in advance brings about the appropriate action at some time in the future

This preamble suggest that schizophrenia does not allow for such a schedule, confidently to be held in mind,

This type of memory, which appears to be impaired by schizophrenia, enables you to remember that you have to do something in the future, without being prompted by something else or somebody else
Ordinarily there is a schedule framework 'inside' which 'reminds' , holds in mind the thing that has to be done at a certain time, does the prompting - time of day - relationship to something else [ a built in prompt - revives what is necessary for the act to be done, soon, tomorrow, next week, whatever ] so as to keeping holding on that topic and keeping to the point or getting back to it ]

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To test their hypothesis the researchers, based at NIMH and at the University of Warwick, compared the prospective memory of people with and without the disease.
In each test participants manoeuvred a ball around an obstacle course for 90 seconds.

The ongoing activity was a commercial battery-powered game ("Kongman"; TOMY Toy Corporation, 1982) in which a steel ball was to be moved around an obstacle course by pressing a button at the appropriate time points in order to open or close certain routes through which the ball could travel. Each game lasted 90 seconds, and participants were instructed to accumulate as many points as possible during each game until the time was up.

The game commenced by each participant winding a timer at the base of the game. During the course of the game the timer moved from the start to the finish position (taking 90 seconds).
The rim surround of the timer was covered and colored with red and green colored paper, such that the first 25 seconds were red and the remaining 65 seconds green.

The Prospective Memory task was to turn a counter (a poker chip that was similar on both sides) over once during each game.
However, participants were instructed to turn the counter over only when the timer reached the green zone (i.e., they could not respond prospectively immediately, but had to wait for some proportion of time into the game before responding).

Participants were to play the game a total of 10 times (i.e., 10 trials). After each of the ten games, participants were asked if they had remembered to turn the counter over during the game. The experimenter employed a stopwatch to note the time at which the counter was turned over, and whether it was in the green or red zone. The participants' response to the question concerning whether they remembered to turn over the counter was also noted. The game was sufficiently easy and enjoyable that participants engaged in the game and all participants performed extremely well. They were asked [ the holding injunction ] to turn over a counter when they were at least 25 seconds into the test.

The time delay ensured that prospective [ i.e. recall for a future event ] memory had to be used.

Participants with schizophrenia were more likely to forget to turn over the counter.

At the end of the test the participants were asked if they had remembered to turn over the counter.

Approximately a third of the time participants with schizophrenia reported they had done so when they had not.

B.

a study published in the British Journal of Psychiatry 2000

Cognitive function in a catchment-area-based population of patients with schizophrenia

C KELLY et al: Academic Department, Gartnavel Royal Hospital, Glasgow, Scotland.

All patients with schizophrenia in a catchment area were identified (n=182).

Measures of assessment were: National Adult Reading Test (NART),

Mini-Mental State Examination (MMSE),

go to ( see below ) Rivermead Behavioural Memory Test (RBMT),

Executive Interview (EXIT),

FAS Verbal Fluency and

Health of the Nation Outcome Scales (HoNOS).

 

Results We assessed 138 patients, mean age 48 years (standard deviation (s.d.) 15). Only 14% were in-patients. The mean premorbid IQ as assessed by NART was 98 (s.d. 14);

15% of patients had significant global cognitive impairment (MMSE);

81% had impaired memory (RBMT see below );

25% had executive dyscontrol (EXIT);

and 49% had impaired verbal fluency (FAS).

Scores on the functional impairment sub-scale of HoNOS correlated with all measures of cognitive impairment.

Conclusions Cognitive dysfunction is pervasive in a community-based population of patients with schizophrenia.

C.

 

Measuring memory impairment in community-based patients with schizophrenia

B J PSYCHIATRY 2006 189 132-136

a Case-control study

Correspondence: Dr Mohammed Al-Uzri, Neuropsychopharmacology Unit, Department of Health Sciences, Leicester General Hospital,
Leicester LE5 4PW, UK. Tel(0) 116 225 7924; fax: +44(0) 116 225 7925; email: mmaul@le.ac.uk

Department of Health Sciences, University of Leicester and Leicestershire Partnership NHS Trust
J. Bruce, MBChB, MRCPsych, S. Frost, MBBS, MRCPsych and D. Mackintosh, MBChB, MRCPsych Leicestershire Partnership NHS Trust

We identified every patient with a possible diagnosis of schizophrenia, from psychiatric records, in one catchment area of approximately 100 000 people in south Leicestershire. This included examining old records of all psychiatric patients in the catchment area to make sure no potential patient was missed. The diagnoses were confirmed using ICD-10 criteria (World Health Organization, 1992). The area can be described as a suburban British residential area with a predominantly middle-class working population. The two consultants responsible for the area have a policy of not discharging patients with schizophrenia from their care even if the patients need minimal psychiatric input. The only exceptions were cases of severe and incapacitating schizophrenia that necessitated a referral to rehabilitation psychiatry. Such patients usually move out of the area into long-term care units or sheltered accommodation.

We excluded patients with organic brain disease, head injuries or comorbidity, and those whose first language was not English. None of the participants had had electroconvulsive therapy in the year prior to taking part in the study. Patients older than 60 years were also excluded, because Kelly et al (2000) suggested that people above this age with schizophrenia have a poorer cognitive performance than younger patients. The patients' performance on the memory test was compared with that of controls (n=71). Members of the control group live in the same city and were recruited by advertisements in the local hospital, university and supermarkets. They had no history of mental illness, and were subjected to the same exclusion criteria as the patient group.

Measures

Rivermead Behavioural Memory Test Participants were assessed with the Rivermead Behavioural Memory Test (RBMT; Wilson et al, 1985). This test of everyday memory has good ecological validity, and is made up of 12 measures, each aimed at testing one aspect of everyday memory:-

a. remembering a name;
b. remembering a hidden belonging;
c. remembering an appointment;
d. picture recognition;
e. immediate recall of a newspaper article;
f. delayed recall of a newspaper article;
g. face recognition;
h. remembering a new route (immediate);
i. remembering a new route (delayed);
j. delivering a message;
k. orientation questions;
l. knowing the date.

The RBMT has a screening score ( 0-12 simply pass or fail ), and is not very demanding in terms of effort or time (it takes 25-30 min to administer). It has been used before in schizophrenia studies, for example by McKenna et al (1990) and Kelly et al (2000)..... back to top

National Adult Reading Test
The National Adult Reading Test (NART; Nelson, 1982) is an estimate measure of premorbid intelligence. It has been widely used in psychiatric research and in particular in studies of schizophrenia (Gilvarry et al, 2001).

Positive and Negative Syndrome Scale

The Positive and Negative Syndrome Scale (PANSS; Kay et al, 1987) was given to patients only. It is a widely used scale for symptom ratings in schizophrenia. Health of the Nation Outcome Scales The Health of the Nation Outcome Scales (HoNOS; Wing et

 

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We report a high prevalence of memory impairment (over 80%) in a population-based study of patients with schizophrenia.
This is based on the screening score of the RBMT, where a score of less than 10 is considered to represent impaired memory. This is, to the best of our knowledge, the second population-based study of cognitive impairment in schizophrenia after that by Kelly et al (2000). Significantly, we were able to replicate their findings regarding memory impairment using the same test, but in a demographically different population.

The patients who took part in our study were relatively young and free from psychotic symptoms, living in the community and with no documented comorbidity. The exclusion criteria were also designed to avoid the participation of any patients disadvantaged in terms of age and language. Except for years in education, there was no significant demographic or clinical difference between the patients who took part in the study and those who declined. This suggests that participants might have better memory functioning than those who declined to take part in the study.

Therefore, the prevalence of memory impairment reported would be a conservative estimate of its overall prevalence in schizophrenia when taking other confounding factors (clinical or demographic) into consideration. This is supported by the findings of Tamlyn et al (1992) who used the same test (RBMT) to examine their cohort; they reported a much higher prevalence of memory impairment in their subgroup of chronically ill and hospitalised patients, 27 out of 28 of whom scored in the impaired range.

The prevalence of schizophrenia in our study population (1.9 per 1000) is at the lower end of that expected (1.4-4.6 per 1000 population; Jablensky, 2000).
This could be explained by the demographic characteristics of the catchment area. As a suburban district, it is more likely to have a lower prevalence of psychotic disorders compared with city centres, which are associated with higher morbidity in general (Mortensen et al, 1999). In addition, patients who develop schizophrenia might well migrate towards the city centre, especially when they need supported or hostel accommodation, which is most likely to be available in urban areas.
This was particularly true for our study because patients who needed rehabilitation services and supported accommodation were moved outside the catchment area.

RBMTand schizophrenia

Our study suggests that the RBMT is a good clinical marker for memory impairment in schizophrenia. This is supported by previous use of the RBMT in studies of schizophrenia, which consistently showed that people with this disorder underperform on this test (McKenna et al, 1990; Kelly et al, 2000).
Our study had the advantage, compared with previous studies, of the inclusion of a control group. This made it possible to examine the ability of the RBMT in discriminating between patients and controls. It is not common in psychiatric research to have an instrument with such a good ability (76%) to predict patient or control status.
A similar ability (76%) was reported in previous work (Palmer et al, 1997); however, this involved a more demanding neuropsychological battery which is difficult to incorporate into everyday clinical practice, and furthermore lacked the specificity of everyday memory.

Therefore, the RBMT has the potential to become an important tool in our clinical practice for the identification of memory impairment in schizophrenia, which may help predict functional outcome.

Specificity of memory impairment

The premorbid IQ reported for the patients in this study was much higher than that reported in previous studies. This is another indication that our sample can be considered among the less ill of patients with schizophrenia, making the memory impairment reported even more significant. The difference in premorbid IQ between patients and controls was small in clinical terms, but statistically significant.

However, even after correcting for this difference in premorbid IQ, patients' performance on the RBMT was worse than that of controls.

Therefore, the underperformance of patients on the RBMT, as a measure of working memory, cannot be explained as a symptom of generalised reduction of intellectual ability, but is rather a specific cognitive deficit. Furthermore, this deficit was not related to symptom rating, except for negative symptoms, or medication in clinically stable patients. This supports the view that memory impairment is a core element of the clinical presentation of schizophrenia. The association between memory impairment and the negative symptoms sub-scale of the PANSS is an important replication of previous findings (Berman et al, 1997). Conceptually, both denote the lack of a normally existing function. More importantly, this is further evidence that they may have a common underlying substrate (Rossi et al, 1997). This is an important contribution of neuropsychology towards better understanding of the underlying pathophysiology of schizophrenia.

Memory impairment and level of functioning

The association of memory impairment with occupational group provides further evidence for the importance of such impairment in schizophrenia. This echoes previous findings (Green, 1996), which suggested an association between memory impairment and functional outcome.

This would have important implications for the development of any intervention that involves the use of memory.

First, it suggests that patients with such impairment might not benefit from interventions that require intact memory.

Second, it might be necessary to include memory remediation programmes in rehabilitation services to improve level of functioning. Further validity for the RBMT comes from the significant correlation with the functional impairment sub-scale of the HoNOS. This finding echoes that previously reported by Kelly et al (2000), which reinforces the importance of memory impairment in influencing level of functioning in patients with mental illness.

Age and memory impairment

An interesting finding emerged when we divided the patient and control groups, separately, into three different age categories.

The average RBMT scores for the controls were not significantly different across age-groups and remained within the normal memory category.
In contrast, the patients' average RBMT scores remained within the impaired memory range across age-groups.
In addition, there was a significant reduction in the average score for the oldest group of patients, which suggests that memory impairment as a subset of cognitive performance is compromised before the age of 60 years (cf. Kelly et al, 2000).

We can conclude that memory decline might have a different course in schizophrenia compared with that in the general population and that older people with schizophrenia (aged 46-60 years) are significantly disadvantaged compared with younger people with this disorder.

The significance of the association between illness duration and memory impairment reported in this study raises important issues. Ostensibly, one can conclude that memory function in schizophrenia has a deteriorating course.

However, it is important to examine the impact of potential mediating factors, such as the course of the illness, before such a conclusion can be drawn definitively.
This is particularly important in the absence of clear neuropathological evidence to support a degenerative nature of the illness (Woods, 1998).

Therefore, what can be concluded from the result of this study is that longer illness duration might carry a higher risk of worsening functional memory impairment.

extracted from the original article

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A try at Repair ?

Semantic hyperpriming in schizophrenia:- Laurent Lecardeur Centre de Recherche Fernand-Seguin, Montréal, Québec H1N 3V2, Canada.
Email:lecardeur@cyceron.fr Sonia Dollfus Centre Esquirol, CHU de Caen Centre d’Imagerie, Neurosciences et d’Application aux Pathologies,
UMR 6232 14074 Caen, France Emmanuel Stip Centre de Recherche Fernand-Seguin Hôpital, Louis-H. Lafontaine, Montréal, Québec, Canada

Impairment of memory is one of the principal cognitive symptoms of schizophrenia. Pomarol-Clotet et al1 reported on a meta-analysis in which they evaluated the results of studies on semantic priming in schizophrenia.
Semantic priming is a component of long-term implicit memory. They argued that hyperpriming (i.e. greater semantic priming in patients than healthy controls) could be an artefact of a general slowing in schizophrenia. As a consequence, these authors aimed to consider general slowing as a moderator variable in their statistical analysis.

The measure of general slowing that they chose corresponded to the difference in response time between controls and patients, when prime and target were unrelated. In our opinion, this measure is not the most suitable as it reflects other cognitive processes. Individuals need to inhibit the prime so as to be able to process the target, since prime and target do not share any semantic relationship.

Consequently, response time in an unrelated condition could be the expression of an accurate inhibitory process rather than of a general slowing as proposed by the authors. Some arguments support this view. First, we evaluated slowing in a simple reaction task in two different studies.2,3
Values were included as covariates in the analyses of covariance of priming effects. Despite confirming general slowing, there was evidence of significant increased priming in patients with schizophrenia compared with controls.

Consequently, hyperpriming can be demonstrated even if general slowing is taken into account and controlled.
Second, we demonstrated that the time required to inhibit an unrelated prime was significantly enhanced in patients with schizophrenia compared with healthy controls.
General slowing was also controlled.
Consequently, we demonstrated that the increased priming effect in patients compared with controls was mainly induced by increased time required to inhibit the unrelated prime.

Our results support impairment of the inhibition of semantically unrelated information in patients with schizophrenia.

Pomarol-Clotet et al suggested that ‘the greater the slowing, the greater the amount of priming’.

Given our results, an alternative explanation has to be considered.

We suggest that hyperpriming in patients with schizophrenia could reflect decreased abilities to inhibit irrelevant information such as semantically unrelated information.

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REFERENCES 1 Pomarol-Clotet E, Oh TMSS, Laws KR, McKenna PJ. Semantic priming in schizophrenia: systematic review and meta-analysis. Br J Psychiatry 2008; 192: 92 –7.[Abstract/Free Full Text] 2 Lecardeur L, Giffard B, Laisney M, Brazo P, Delamillieure P, Eustache F, Dollfus S. Semantic hyperpriming in schizophrenic patients. Increased facilitation or impaired inhibition in semantic association processing? Schizophr Res 2007; 89: 243 –50.[CrossRef] [Medline] 3 Lecardeur L, Brazo P, Dollfus S, Giffard B, Laisney M, Eustache F, Stip E. Does hyperpriming reveal impaired spreading of activation in schizophrenia? Schizophr Res 2007; 97: 289 –91.[CrossRef] [Medline]

In the largest UK study of twins with schizophrenia two hundred sixty seven twins were invited to complete a comprehensive series of intelligence and memory tests. Both identical and non-identical twins took part, in some pairs both twins were affected by the illness and in others only one twin. Sophisticated genetic modelling statistical analyses were then used to determine to what extent the intelligence deficits were related to the genetic risk for the illness.

The researchers found a significant correlation between intelligence and schizophrenia with 92% of the covariance between the two accounted for by shared genetic variance. Genetic influences also explained most of the covariance between working memory and schizophrenia.
Environmental effects, though separately linked to neurocognition and schizophrenia did not in general contribute to their correlation. These results imply that to some extent the genes that influence schizophrenia are the same as those responsible for intelligence and working memory. Identifying those genes would effectively allow us to identify some of the genes contributing to schizophrenia.

Substantial Genetic Overlap between Neurocognition and Schizophrenia: Genetic Modelling in Twin Samples

authored by Timothea Toulopoulou; Marco Picchioni; Fruhling Rijsdijk; Mei Hua-Hall; Ulrich Ettinger; Pak Sham; Robin Murray Arch Gen Psychiatry 2007;64 1348-1355

prospective memory at fault: an experimental study

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