Memory Complaints, Mild Cognitive Impairment and Dementia

Essentials

• Dementia symptoms and clear impairment of cognitive capacity are not a part of normal aging.
• One in three individuals over 65 years experiences symptoms of memory loss, but the majority of them do not have a progressive memory disease.
• Even of those in working age, 10-20% experience difficulties with memory or other areas of cognitive functioning.
• Memory disease may begin also with impairment of visual perception, executive functioning or linguistic abilities.

Memory and normal aging

• Normal age-related changes in memory and cognitive functions are relatively minor, and by themselves they do not have a significant impact on the person's functioning in daily activities or social situations.
• Mild impairment may be seen in the speed of cognitive functions and efficiency of working memory already from the middle age onwards, but changes related to ageing are seen most clearly after the age of 70.
• When people age in a healthy way, orientation, general comprehension and logical thinking are preserved, they do not become "senile".
• A normal elderly person is capable of learning, albeit learning may be slower.
• 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 from memory
  • efficiency of the active short-term memory (“working memory”)
  • speed of cognitive processes
  • cognitive functions that require flexibility.
• However, no decline is seen in the following functions
  • retaining information
  • cued recall and recognition memory
  • ability to learn in general
  • managing knowledge and skills acquired earlier.

Epidemiology

• According to the WHO, over 55 million people were living with dementia in 2019 http://apps.who.int/iris/bitstream/handle/10665/344701/9789240033245-eng.pdf.
• 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 are seen in the cognitive domains. Different aspects of cognition include e.g.: attention, executive functioning, deductive reasoning, orientation, language, visual perception, memory, visuomotor and motor skills, as well as the speed of cognitive functions.
• 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 also these affect the learning of new things and the function of memory.
• Mild cognitive impairment (MCI) is a symptom description. It refers to a situation where an individual self-reports memory problems, or has other subjective symptoms of declining cognitive performance, and an impairment compared to the premorbid level has been shown objectively in one or more cognitive domains. However, the ability to carry out everyday activities has been fairly well preserved, and the patient does not meet the criteria for a specific memory disease. MCI is not an aetiological diagnosis but a collection of symptoms which may originate from multifactorial aetiologies. Nowadays, typical memory diseases may 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 (memory disorder prior to dementia syndrome).
• A memory disease refers to a brain 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 brain disease (e.g. AD), permanent sequela related to a central nervous system disease (e.g. brain damage) or a treatable condition (e.g. encephalitis Encephalitis). 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 significant other over the impairment of the person's memory function or of other area of cognitive capacity, as compared to earlier status
• Detection of subjective, persistent memory difficulties that are experienced as clearly impeding
• Impairment of functional capacity: memory lapses impede the performance of work or domestic tasks
• Recurring oversight of appointment times and already discussed matters (which cannot be recollected even if they are talked about)
• Difficulty finding words or problems with orientation (sense of time and place)
• Difficulties in visual perception and perceptual errors (difficulty in reading, losing belongings, getting lost)
• Impairment of problem solving or of managing complex tasks (e.g. financial matters, work assignments)
• Impairment of conceptual thinking and reasoning (thinking becomes more restricted, things that have been learned before do not go well)
• Change in personality, loss of control, suspiciousness or fearfulness
• Decline of initiative, withdrawal from social contacts (apathy)
• Poor recognition of symptoms or anosognosia (e.g. difficulties with memory are spoken about in an interview, but the person him-/herself does not recognize them or downplays their effects)
• During the consultation, the physician, nurse or psychologist starts to suspect impairment of cognitive processes ("one needs to explain things multiple times, actions are illogical; the patient gets stuck, cannot focus on the topic or is unhibited").
• Inappropriate use of health care services, diffulty following treatment instructions
• Proness to confusion or poor recuperation in association with acute illness or surgical operation

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)

• The underlying factors of memory symptoms can be divided into transient causes, chronic disease sequelae, progressive brain diseases and treatable causes independent their mechanism.
• The cause ofmemory symptoms and changes in cognitive functioning should always be traced. Basic investigations aim at identifying depression, vitamin deficiencies and other treatable causes and at discovering situations that warrant closer neurological investigations.

Dementia