Memory Complaints, Mild Cognitive Impairment and Dementia

Essentials

• Dementia symptoms and significant impairment of cognitive capacity are not a part of normal aging.
• One in three individuals over 65 years presents with subjective memory complaints, but the majority of them do not have a progressive memory disease.
• Even of those in working age, one out of five experience difficulties with memory and/or concentration.
• Memory disease may begin with some other symptom than one related to memory.

Memory and normal aging

• Normal age-related changes in memory and cognitive functions are relatively minor, and they do not have a significant impact on the person's daily activities or social competence.
• A normal elderly person is capable of learning, albeit more slowly, and thus is not "senile".
• Knowledge and skills acquired earlier are well preserved in healthy ageing.
• The normal ageing process involves a slight decline in functions such as
  • ability to memorize and retrieve information
  • efficiency of the active short-term memory (“working memory”)
  • speed of cognitive processes
  • reasoning that requires flexibility
  • memory capacity and susceptibility to distraction.
• However, no decline is seen in the following functions
  • ability to retain information
  • cued recall and recognition memory
  • ability to learn in general
  • managing knowledge and skills acquired earlier.

Epidemiology

• In Finland, 8.1% of individuals over 65 years of age suffer from moderate to severe memory disorder.
• Of patients with a memory disorder, the majority (66%) are over 80 years old.
• Three out of four elderly patients in long-term institutional care have a memory disorder.

Definitions

• Cognitive symptoms refer to problems that reflect a decline in the cognitive domains. Different aspects of cognition include e.g.: attention, executive functioning, deductive reasoning, orientation, language, memory, visuomotor and motor skills, as well as visuospatial and visuoconstructive abilities.
• In cognitive symptoms it is important to distinguish between the subjective symptoms experienced by the person him-/herself, the cognitive difficulties reported by family members and close friends, and cognitive impairments detected objectively (by psychological/neuropsychological tests).
• Memory complaints are usually related to difficulties encountered in either the short term (“working”) memory, the episodic, or the semantic memory. This may be caused by changes in the function of the frontal or temporal lobe resulting in an impaired ability to memorize, store and retrieve information. The assessment of memory complaints should also take into account attention and executive function, since these affect the learning of new things and the function of memory.
• Mild cognitive impairment (MCI) is a symptom term. It refers to a situation where an individual self reports memory problems, or has other subjective symptoms of declining cognitive performance, and a clear deterioration from the premorbid level has been shown objectively for one or more cognitive domains. However, the ability to carry out normal daily activities has been fairly well preserved, and the patient does not meet the criteria for a specific memory disease. MCI is not a diagnosis as such but a collection of symptoms originating from multifactorial aetiologies. A memory disease may, however, usually be diagnosed already at the stage of MCI if appropriate special investigations (neuropsychological examination, imaging and biomarker studies) are carried out at an early enough stage. In such cases the condition is referred to as an early memory disorder.
• A memory disease refers to a disease that results in a decline both in memory and other cognitive functions, such as verbal functions, visual perception and executive functions. Progressive memory diseases usually result in a decline in memory and cognitive functions to a degree sufficient to cause dementia. The most common memory diseases are: Alzheimer's disease (AD), memory disorder associated with cerebrovascular disease (large vessel disease, small vessel disease, infarcts resulting in critical cognitive impairment), diseases connected with Lewy body pathology, including the memory disorder in Parkinson's disease and Lewy body dementia, as well as frontotemporal lobar degeneration (frontotemporal dementia, progressive nonfluent aphasia, semantic dementia).
• By definition, dementia refers to a decline in more than one cognitive function, from the premorbid level, that is sufficient to cause significant impairment in the ability to cope independently with daily activities, work and social relationships. Dementia is a syndrome, not a disease in itself. In dementia, the cognitive impairment is due to an organic cause. Dementia may be caused by a progressive disease (e.g. AD), permanent sequela (e.g. brain damage) or a treatable condition (e.g. hypothyroidism Curable Causes of Memory-Related Symptoms and Diseases). Memory diseases that result in dementia (e.g. AD) are known as progressive memory diseases.

When to suspect a memory disease?

• Concern expressed by a family member over the impairment of the patient's memory function or of other area of cognitive capacity, as compared to earlier status
• Subjective, persistent memory lapses that are considered as impeding
• Impairment of functional capacity: memory lapses impede the performance of work or domestic tasks
• Oversight of appointment times and already discussed matters (which cannot be recollected even if they are talked about), inappropriate use of health care services, difficulty following treatment instructions
• Proneness to confusion or poor recuperation in association with acute illness or surgical operation
• Difficulty finding words or problems with orientation (sense of time, proneness to getting lost)
• Difficulties in visual perception and perceptual errors
• Impairment of reasoning and problem solving, as well as of managing complex tasks
• Impairment of conceptual thinking, e.g. difficulties in taking care of financial matters
• Change in personality, suspiciousness or fearfulness
• Decline of initiative, withdrawal from social contacts
• Poor recognition of symptoms (e.g. difficulties with memory are spoken about in an interview, but the person him-/herself does not recognize them or downplays them)
• During the consultation, a change in the patient's mental acuity arouses the suspicion of the physician or nurse ("one needs to explain things multiple times, a peculiar, strange patient").

Causes and assessment of memory impairments Mini-Mental State Examination (Mmse) for the Detection of Dementia in Clinically Unevaluated People Aged 65 and over in Community and Primary Care Populations, CSF Tau and the CSF Tau/Abeta Ratio for the Diagnosis of Alzheimer's Disease Dementia and other Dementias in People with Mild Cognitive Impairment (Mci)

• Common causes of memory symptoms can be grouped to transient causes, chronic disease sequelae, progressive diseases and treatable causes independent of the mechanism of the memory impairment.
• The cause ofmemory symptoms and changes in cognitive functioning should always be traced. Basic investigations aim at identifying depression and other treatable causes and at discovering memory symptoms that warrant further investigations.

Dementia