Brain reserve and the prevention of dementia

Purpose of review To evaluate and synthesize recent evidence linking mental activity and dementia risk, which commonly invokes ‘brain reserve’ as the mediating construct. Recent findings Brain reserve has acquired several interpretations; however, the most reliable and practical definition focuses at the behavioural level by assessing frequency and range of participation in complex mental activities. Epidemiological research suggests a clear and consistent link of high brain reserve with reduced dementia risk. Furthermore, emerging clinical trials of cognitive exercise suggest that it may be effective for the prevention of longitudinal cognitive and functional decline. Recent animal studies implicate several mechanisms, including disease-dependent and disease-independent compensatory pathways. Summary Given the precipitous forecasts for dementia over the coming decades, effective preventive strategies are of utmost importance. Findings from brain reserve studies now meet many of the formal criteria for causal agency between complex mental activity and reduced dementia risk. Key clinical trials are therefore under way to test these claims and results are keenly awaited.

[1]  A. Hannan,et al.  Enriched environments, experience-dependent plasticity and disorders of the nervous system , 2006, Nature Reviews Neuroscience.

[2]  H. Kavirajan,et al.  Benefits of cognitive-motor intervention in MCI and mild to moderate Alzheimer disease , 2005, Neurology.

[3]  L. Bäckman,et al.  Design your own memory strategies! Self-generated strategy training versus mnemonic training in old age: An 8-month follow-up , 2005, Neuropsychological rehabilitation.

[4]  Ted Abel,et al.  Recombinant BDNF Rescues Deficits in Basal Synaptic Transmission and Hippocampal LTP in BDNF Knockout Mice , 1996, Neuron.

[5]  A. B. Hill.  The Environment and Disease: Association or Causation? , 1965, Proceedings of the Royal Society of Medicine.

[6]  D. Jeste,et al.  Cognitive training in Alzheimer's disease: a meta‐analysis of the literature , 2006, Acta psychiatrica Scandinavica.

[7]  F. Gage,et al.  Neural consequences of enviromental enrichment , 2000, Nature Reviews Neuroscience.

[8]  A. Roses,et al.  ApoE4 impairs hippocampal plasticity isoform-specifically and blocks the environmental stimulation of synaptogenesis and memory , 2003, Neurobiology of Disease.

[9]  J. Morris,et al.  Education and Alzheimer disease without dementia , 2007, Neurology.

[10]  J. Altman,et al.  Behaviorally induced changes in length of cerebrum in rats , 1968 .

[11]  Michael J. Valenzuela,et al.  Memory training alters hippocampal neurochemistry in healthy elderly , 2003, Neuroreport.

[12]  D. Bennett,et al.  Cognitive leisure activities, but not watching TV, for future brain benefits , 2006, Neurology.

[13]  Anthony F Jorm,et al.  The advantage of being broad-minded: Brain diameter and neuropsychological test performance in elderly war veterans , 1997 .

[14]  S. Scheff,et al.  Synaptic pathology in Alzheimer’s disease: a review of ultrastructural studies , 2003, Neurobiology of Aging.

[15]  Y. Stern,et al.  An association between head circumference and Alzheimer's disease in a population-based study of aging and dementia , 1997, Neurology.

[16]  M R Rosenzweig,et al.  Effects of differential environments on brain weights and enzyme activities in gerbils, rats, and mice. , 1969, Developmental psychobiology.

[17]  T. Klingberg,et al.  Increased prefrontal and parietal activity after training of working memory , 2004, Nature Neuroscience.

[18]  Ilana S. Hairston,et al.  Environmental Enrichment Reduces Aβ Levels and Amyloid Deposition in Transgenic Mice , 2005, Cell.

[19]  H. Tuokko,et al.  Cognitive decline in high-functioning older adults: Reserve or ascertainment bias? , 2003, Aging & mental health.

[20]  P. Eriksson,et al.  Environmental enrichment and the brain. , 2002, Progress in brain research.

[21]  Victoria M Perreau,et al.  Voluntary Exercise Decreases Amyloid Load in a Transgenic Model of Alzheimer's Disease , 2005, The Journal of Neuroscience.

[22]  Sharona M. Atkins,et al.  Memory enhancement in healthy older adults using a brain plasticity-based training program: A randomized, controlled study , 2006, Proceedings of the National Academy of Sciences.

[23]  R. Katzman.,et al.  Clinical, pathological, and neurochemical changes in dementia: A subgroup with preserved mental status and numerous neocortical plaques , 1988, Annals of neurology.

[24]  D. Salmon,et al.  Physical basis of cognitive alterations in alzheimer's disease: Synapse loss is the major correlate of cognitive impairment , 1991, Annals of neurology.

[25]  M. Carlson,et al.  Training and Maintaining Memory Abilities in Healthy Older Adults: Traditional and Novel Approaches. , 2007, The journals of gerontology. Series B, Psychological sciences and social sciences.

[26]  J. Schneider,et al.  Participation in cognitively stimulating activities and risk of incident Alzheimer disease. , 2002, JAMA.

[27]  A. Artola,et al.  Long‐lasting modulation of the induction of LTD and LTP in rat hippocampal CA1 by behavioural stress and environmental enrichment , 2006, The European journal of neuroscience.

[28]  P. Sachdev,et al.  Assessment of complex mental activity across the lifespan: development of the Lifetime of Experiences Questionnaire (LEQ) , 2006, Psychological Medicine.

[29]  L. Goossens,et al.  Improving memory performance in the aged through mnemonic training: a meta-analytic study. , 1992, Psychology and aging.

[30]  M. Breakspear,et al.  Complex mental activity and the aging brain: Molecular, cellular and cortical network mechanisms , 2007, Brain Research Reviews.

[31]  A. S. Neely,et al.  Long-Term Maintenance of Gains From Memory Training in Older Adults: Two 3½Year Follow-up Studies , 1993 .

[32]  J. Bienias,et al.  A three-year follow-up of older adult participants in a memory-skills training program. , 1988, Psychology and aging.

[33]  J. Gallacher,et al.  Commentary: Activity each day keeps dementia away--does social interaction really preserve cognitive function? , 2005, International journal of epidemiology.

[34]  R. Rupprecht,et al.  Differential effects of single versus combined cognitive and physical training with older adults: the SimA study in a 5-year perspective , 2006, European journal of ageing.

[35]  Y. Stern.  What is cognitive reserve? Theory and research application of the reserve concept , 2002, Journal of the International Neuropsychological Society.

[36]  P. Sachdev,et al.  Brain reserve and dementia: a systematic review , 2005, Psychological Medicine.

[37]  G. Knott,et al.  Altered Synapse Formation in the Adult Somatosensory Cortex of Brain-Derived Neurotrophic Factor Heterozygote Mice , 2004, The Journal of Neuroscience.

[38]  D. Borchelt,et al.  Environmental Enrichment Mitigates Cognitive Deficits in a Mouse Model of Alzheimer's Disease , 2005, The Journal of Neuroscience.

[39]  George W Rebok,et al.  Effects of cognitive training interventions with older adults: a randomized controlled trial. , 2002, JAMA.

[40]  Y. Stern,et al.  Influence of leisure activity on the incidence of Alzheimer’s Disease , 2001, Neurology.

[41]  A. Davison.  Etiology of dementia of Alzheimer's type By A.S. Henderson and J.H. Henderson (eds.), Life Sci. Res. Rep. 43, John Wiley & Sons, New York, 1988 , 1989, Journal of the Neurological Sciences.

[42]  T del Ser,et al.  Benefits of cognitive-motor intervention in MCI and mild to moderate Alzheimer disease , 2004, Neurology.

[43]  Paige E. Scalf,et al.  Aerobic exercise training increases brain volume in aging humans. , 2006, The journals of gerontology. Series A, Biological sciences and medical sciences.

[44]  Laura Fratiglioni,et al.  Late-life engagement in social and leisure activities is associated with a decreased risk of dementia: a longitudinal study from the Kungsholmen project. , 2002, American journal of epidemiology.

[45]  L. Bäckman,et al.  Long-term maintenance of gains from memory training in older adults: two 3 1/2-year follow-up studies. , 1993, Journal of gerontology.

[46]  P. Satz.  Brain reserve capacity on symptom onset after brain injury: A formulation and review of evidence for threshold theory. , 1993 .

[47]  J. Dartigues,et al.  Leisure activities and the risk of dementia in the elderly , 2007 .

[48]  D. Commenges,et al.  Social and Leisure Activities and Risk of Dementia: A Prospective Longitudinal Study , 1995, Journal of the American Geriatrics Society.

[49]  P. Sachdev,et al.  Brain reserve and cognitive decline: a non-parametric systematic review , 2006, Psychological Medicine.

[50]  S. Paul,et al.  Enrichment improves cognition in AD mice by amyloid-related and unrelated mechanisms , 2007, Neurobiology of Aging.

[51]  K. Ball,et al.  Long-term effects of cognitive training on everyday functional outcomes in older adults. , 2006, JAMA.

[52]  A. May,et al.  Structural brain alterations following 5 days of intervention: dynamic aspects of neuroplasticity. , 2007, Cerebral cortex.

[53]  J. Mortimer,et al.  Brain reserve and the clinical expression of Alzheimer's disease. , 1997, Geriatrics.

[54]  B. Winblad,et al.  Influence of social network on occurrence of dementia: a community-based longitudinal study , 2000, The Lancet.

[55]  A. Granholm,et al.  Long-Term Environmental Enrichment Leads to Regional Increases in Neurotrophin Levels in Rat Brain , 2000, Experimental Neurology.

[56]  H. Buschke,et al.  Leisure activities and the risk of dementia in the elderly. , 2003, The New England journal of medicine.

[57]  C. Rampon,et al.  Genetic analysis of learning behavior‐induced structural plasticity , 2000, Hippocampus.